First, a note: If you submit a comment and it does not post, please email me at otownes AT gmail DOT com and let me know.
About the blog:
This blog began as a series of e-mails to help train my local SCA rapier practice in melee. In 2008 I decided to start maintaining it as a blog instead, hopefully to reach a wider audience but mostly to have a readily accessible archive for new members of the practice. I foolishly called it Wistric’s Weekly Warfare and thereby made a certain commitment regarding posting frequency (which, statistically speaking, we maintain to this day).
It morphed over time as my rapier pursuits developed into a place to document my thoughts on melee, as well as my experience as a fencer trying to improve and a student of historic martial arts.
In 2011 I received my White Scarf and I decided to open up this platform to others, especially my students. I have no doubt it helped me earn that Scarf, possibly through self-promotion, mostly through forcing myself to think more about what I was doing as a fencer and the feedback I received. At that point it became the Weekly Warfare.
Our contributor list has expanded since then and with it the range of topics and depth and breadth of knowledge. New contributors are always welcome – even the neophyte has a perspective and personal experience that will inform fencers and teachers of all experience levels. Academic writing skills and knowledge are not required – if they were the Warfare would be better off without me as a contributor.
If you’re reading this, please give feedback. “I agree” is fine. “I disagree” is better. “I disagree and this is why” is even better. This is a crucible in which to refine ideas and pick the brains of the audience for how to better understand the Art we do.
If you’d like to know more about a topic, just ask. We’ll see if somebody wants to take a swing at writing about it, or even help you do so.
The sun was in my eyes, my opponent was tall, their blade was longer, my sleeve snagged on something, I slipped, they were a MOD. One of my biggest pet peeves in fencing is when someone loses and then attempts to blame something/someone that deflects all fault from themselves. I have made similar excuses in the past, and every time I do it, I inevitably kick myself for it later for multiple reasons.
One reason is that every time you try to shift the blame away from yourself, you lose a chance to learn, to better yourself and to improve. The sun may have been in your eyes, but why were you in critical measure and staring at a giant ball of flaming gas? You may have slipped, but you know it rained last night. Your opponent was 6’6”, how did you change your tactics, and what could you do better next time? Every deflection deters your progress as a fencer. It is important to remember that there is always something you could have done to change the outcome of the fight. When looking back on your losses – as well as your wins – you should explore what you could have done to improve your chances, it could be anything from better timing, blade positioning, or a different technique. Every pass can always be better.
Deflection of blame also takes away from the glory of your opponent. When you blame your loss on external forces, you are discrediting the skill and choices that led to their victory. Since you lost, their choice was objectively correct. It does not matter if you can beat them 99% of the time. In that bout, they proved themselves the better fencer of that moment, and you can learn from that and from them. Also, you just witnessed a winning choice from the closest seat. Use this information to discover new ways to win. Are your opponents all hitting you in the same area? Defensively, you can work to correct that behavior in yourself and shore up that weakness. Offensively, you can be on the lookout for others who make the same mistake then you can abuse it and this time you walk away with the win.
Losing sucks, but it is important to think about your loss in a productive way. Do not get discouraged, and certainly do not consider your defeat as predetermined. For example, the mindset, “Of course I lost, s/he was a MOD” is entirely unhelpful and sets you up to lose in the future. Think positively! If you lost you can analyze the fight and find things to improve. You can ask mentors and friends if they have good drills for a specific problem. You can ask the opponent who beat you for help or more fights later. You can even have a friend watch or film your fights (though this isn’t always possible) so you can focus on the fight, and know that you will have good information in the aftermath regardless.
From a social perspective you should not deflect blame when you lose a fight because it can really ruin someone’s day. If you credit their victory to your shoelaces being untied, and not to the prowess they have put hours into gaining they can be very easily discouraged. One of my worst tournament experiences was when I, a scholar at the time, beat someone I really looked up to, only to have them brush it away as a fluke. On the other hand, one of my tournament highlights was when I defeated a different mentor and they simply said, “you got me, this time you were better.” This advice is especially important if you are a MOD or White Scarf. I am almost certain that if you lose to a newer or less skilled fencer, your loss means less to you than their win means to them. Accept loss with grace, give credit to the fencer that bested you, and then go learn from it.
(Ed. This is part 5 of a multi-part series. Comments that indicate a failure to read previous entries shall be mocked and, possibly, moderated with extreme prejudice. The author took the time to do the research, you can take the time to read it)
(Part 1Part 2Part 3Part 4)
What Causes Concussions:
As we discussed in article 1, the primary cause of concussions in SCA combat and in HEMA is high levels of acceleration of the head. However, the way that many fighters envision concussions– that they occur because the brain sloshes around and strikes the inside of the skull– is generally incorrect, as this kind of concussion requires far more force than we are using (these require vehicular accident-level forces). Instead, we are almost exclusively dealing with concussions that result from diffuse axonal injury.
The location of an axon in a brain cell (neuron). Image from: http://www.neuroscientificallychallenged.com/glossary/axon/
Diffuse axonal injury is mainly the result of rotational acceleration of the head because this kind of motion creates shearing forces that cut and damage axons throughout the brain. Axons are one of the main parts of brain cells (neurons) and they form long fibers that carry the signal from one brain cell to another. Outside of the brain, axons are what form nerves and most of the spinal cord, and as you can imagine, cutting axons inside the brain is bad. When a neuron has its axon cut or damaged, it can no longer send messages like it is supposed to, which can trigger a neuron to kill itself. Furthermore, this damage creates an inflammatory response that causes other types of damage to the brain and is largely responsible for the symptoms that follow concussions (e.g. tiredness, confusion, memory problems, fuzziness, problems with attention).
Because this is the kind of concussion that we are most likely to receive from SCA combat, we know that any attempt to protect ourselves from concussions must prevent rotational acceleration of the head. In order to see how this works, we must consider what happens when two objects collide.
In physics, when two objects interact, they do so by exerting something called force. Essentially, force is a measurement of the push or pull that one object exerts on the other (or both objects exert on each other). We know from Newton’s First Law of Motion that force must be applied to an object in order to cause it to accelerate. Likewise, we know from Newton’s Second Law of Motion that force is related to acceleration as a consequence of inertia, that is, an object’s tendency to remain stationary or its tendency to continue moving with constant velocity.
To put it another way, inertia is an object’s ability to resist acceleration and force is what causes that acceleration. When we are considering acceleration through space (translational acceleration), an object’s inertia is the same as its mass. However, when we are considering rotational acceleration, we must instead calculate something called a moment of inertia, which takes into account the fact that when an object rotates, not all of its mass is undergoing the same amount of acceleration. Because of this, Newton’s Second Law of Motion provides us with two different equations:
Force = mass * translational acceleration or F = m*a
Torque (τ) = moment of inertia (I) * rotational acceleration (α) or τ = I*α
To put this another way, when a weapon strikes someone’s head, that weapon exerts force on the head and likewise the head resists this force based on its inertia. Since we also know that for every action, there is an equal and opposite reaction (i.e. Newton’s Third Law of Motion), we know that the head also applies an equal amount of force to the weapon (i.e. in the opposite direction). This means that both the weapon and the head will undergo acceleration relative to their respective inertias following a collision because, importantly, force is not conserved in the same way that energy and momentum are conserved. We can see this in the following figure:
Here, F1 is the amount of force applied by the weapon and F2 is the force of resistance provided by the head. Due to Newton’s Third Law of Motion, we know that F2 = -F1, where the negative sign indicates that F2 occurs in the opposite direction from F1. We also know that the acceleration of the head, A2 is the force F1 divided by the mass of the head, m2 due to Newton’s Second Law of Motion. Therefore we know that it is force that causes the head to accelerate.
The blows that cause concussions:
As noted in article 1, the amount of acceleration necessary to cause a concussion is at least 60Gs. This is a fairly high value, so let me be clear, causing a concussion requires you to hit someone with a lot of force.
Because we know that force is dependent on mass and acceleration, we should expect that strikes that place a person’s body mass behind the blow and/or provide a lot of acceleration are the strikes that are most likely to cause concussions. There are a number of techniques that fulfill these requirements, however for the most part, such techniques will fall into one of the following categories:
This is going to have way more than 22lbs of force! Image from: https://www.facebook.com/photo.php?fbid=10208676965068728&set=t.752572217&type=3&theater
Jumping/falling – One of the easiest ways to hit someone hard is to “jump” upwards during your attack such that you are falling when you strike your opponent. These strikes are going to always hit with an amount of force equal to a fighter’s body weight. An extreme example is pictured below. Because Wistric has jumped upwards, if he lands a strike while he is falling, he will hit his opponent with the full ~250lbs of his body weight. This is obviously far more than the 22lb typical blow that Llwyd’s machine recorded (Article 2). Perhaps even more importantly, as long as Wistric’s sword strikes his opponent before his feet hit the ground, there’s absolutely nothing Wistric will be able to do in order to reduce this force. Wistric is also at serious risk of being hit even harder by his opponent, as they may use any of the other techniques here to add their own body mass + muscle strength to the blow. It is also important to keep in mind that this occurs even during far less obvious examples of “jumping.” Any strike where one fighter throws their body forward or upwards, even if it’s only a few inches, runs the exact same risk.
Punching – Professional boxers punch with around 1000 lbs of force, and while the number of us who are professional boxers is near-zero, that doesn’t mean that our punches are anywhere near as gentle as the force levels recorded by Llwyd’s machine. Punching techniques achieve these force levels by engaging core and leg muscles and by coupling the body mass behind the arm by extending it during the strike. As a result, these blows couple the body mass with significant levels of acceleration in order to generate a lot of force.
Kinetic Linking – The kinetic linking used in SCA rattan combat is similar to delivering a punch in many ways, however when these body mechanics are used to perform a cut, they produce a “whipping” action with the sword that can produce extreme levels of acceleration. Swinging a sword is similar in some respects to swinging a baseball bat and adult baseball players frequently have a bat speed in the 70-80 mph range, which is more than 30 m/s. This speed is reached in around a second (if not less), so acceleration of ~30m/s2 is probably a reasonable (if not low) estimate of the acceleration of the weapon. When this is coupled with the mass of a body, it becomes possible to generate an amount of force that is roughly 3x someone’s body weight or more. The key limitation to this ability is that as the point of impact is moved further down the weapon away from the person delivering the strike, it becomes more difficult to place one’s body mass behind the blow (because of the leverage disadvantage). This means that “short stick” strikes are particularly dangerous as they couple a punch with an acceleration advantage provided by the weapon’s leverage.
So, why aren’t we Always getting Concussions?
Once again, we are running into a limitation in the way that we have modelled the impact. In reality, the person receiving the blow is also able to put their body mass into resisting the strike. They do this by engaging their neck muscles (which are stronger than you might expect). If the person receiving the blow does this successfully, then they will dramatically increase the amount of resistance (i.e. the effective mass) of the head against acceleration, which will make it difficultfor a fighter to be concussed by a blow that they were prepared to receive. We can see this play out in other sports. For instance, one of the more interesting findings has been that one of the best methods for reducing concussions has been the introduction of helmet-less tackle drills(Myers et al., 2015), which are thought to train players to avoid head impacts and improve their ability to prepare to take a hit. Being prepared to be struck is also important in other sports like boxing or mixed martial arts. If you watch the following video carefully, you’ll see that the knock-out blows happen when the recipient is unprepared to be struck. More specifically, you’ll see that they occur during moments where the recipient is pulling their head away from the blow, which makes it impossible to actively resist.
A dramatic disparity in body mass/strength is the main limitation to the notion that it is difficult to concuss a fighter who is prepared to receive a blow. Sometimes one fighter is capable of exerting a significantly greater ratio of force than the smaller fighter can resist, but such a blow would clearly be excessive, even on the SCA armored field. However sometimes accidents happen, which is one of the reasons why technique and conditioning are important as discussed in article 4. This is also a large part of why weight classes exist in other combat sports and why neck strength conditioning is considered to be very important in sports like football, boxing, and wrestling.
The ability to resist impacts to the head with your musculature is the primary means of protection against brain injuries.
We should also avoid coming to the conclusion that if a concussion occurs, it is the recipient who was at fault. It isn’t possible for fighters to be ready to take every hit that they are struck by. This ability is improved with skill, practice, etc, but even in the video above, we see professional fighters caught unprepared.
Ultimately, this means that concussion protection largely boils down to not hitting too hard, particularly when your opponent is unaware/unprepared to be struck.
What about a Helmet?
Helmets are relevant to protecting against concussions only when the recipient is unprepared, because,as we have just seen, it is really hard to concuss someone who is prepared to receive a blow. Helmets are therefore a form of passive protection for instances where a fighter is unprepared to be struck. Unfortunately, concussion protection is in its relative infancy. It is only in the last few years that the consequences of concussions have been seen as anything more than a temporary inconvenience and so preventing brain injuries is not something that most protective equipment has been designed to do. Instead of reducing the acceleration of the head, helmets instead are designed to minimize pressure by spreading impacts out over a greater area. This is useful for preventing pain, bruising, pressure cuts, facial bone/skull fracture, eye/ear damage, hearing loss, and other soft-tissue injuries. However, helmets do not generally spread an impact out over a greater portion of the body than the head. This means that they provide nearly zero effective protection against the acceleration of the head. In other words, if something is only attached to the head, it can’t spread an impact out over more than the head. Despite this, the SCA’s traditional wisdom seems to believe that either the mass of the helmet or the padding itself will protect against concussions. However, as will be shown, neither of these provide meaningful protection against concussions.
One of the key ways in which a helmet can provide protection to the head is by being heavy. Newton’s Second Law of Motion tells us that the inertia of the head is crucial in determining the amount of acceleration that either undergoes and so clearly adding mass to the head provides some degree of additional protection. However, the mass of even a very heavy helmet is still a full order of magnitude smaller than the mass of your opponent behind their weapon.
Furthermore, since we expect that rotational acceleration is the key to concussions, we also need to understand that the effects of added mass on the moment of inertia are greatly diminished for relatively small objects such as the human head. For instance, the moment of inertia of a sphere is calculated using the equation:
I = ⅖ * mass * radius2
In this equation, radius is measured in meters, and so for an object such as the human head that has a radius of ~10 cm, the effect of mass is multiplied by 0.01 * 0.4 = 0.004. However, it is also worth noting that when calculating rotational acceleration, the acceleration is measured in terms of radians/s2 rather than in meters/s2, so in order to compare this directly with the acceleration threshold of 60Gs, we must convert our acceleration from radians to meters by multiplying the angular acceleration by the radius (i.e. dividing by 10) and so we know that the effect of mass is essentially multiplied by 0.0004 when we are considering its effect on resisting rotation.
While a sphere might be an acceptable model of moment of inertia, we should keep in mind that the head is not a sphere. Calculating the moment of inertia for an irregularly shaped object like the head can be tricky, but fortunately there are a number of researchers who have figured this out for us. Yoganandan et al. (2009) provides a summary of multiple studies that have calculated the moment of inertia of the human head for rotation around the x (left-right tilt), y (up-down rotation), and z (left-right rotation) axes using human cadavers.
The orientation of the x, y, and z axes of head rotation.
In order to find suitable values, I averaged the values found in tables 19 and 20, resulting in the following mass and moments of inertia:
Mass: 4.17 kg
Ix = 0.0186 kg-m2
Iy = 0.0215 kg-m2
Iz = 0.0168 kg-m2
In order to calculate the amount of resistance against rotation that added mass provides along each of these axes, we must divide by the average mass:
Ix/kg = 0.0186 kg-m2/4.17 kg = 0.0045 I/kg
Iy/kg = 0.0215 kg-m2/4.17 kg = 0.0052 I/kg
Iz/kg = 0.0168 kg-m2/4.17 kg = 0.0040 I/kg
If we were to consider the effect of a very heavy 10kg helmet and 4kg head, we would need to multiply that 14kg by about 0.0045 in order to figure out the amount of resistance this would provide against the force of an impact (0.063kg). However, in order to see how this relates to our 60G threshold, we must also convert from radians to meters as we did before by dividing the mass of the weapon that we used in the calculator by 10 (because the head has a radius of ~10cm). So we have F = 14kg * 0.0045 * 600m/s2 /0.1m = 378 N = 85lbs.
If we compare that against the head by itself, F = 4kg * 0.0045 * 600m/s2/0.1m = 108 N = 24 lbs. That 50 lb difference may seem like quite a bit of protection if we compare against the amounts of force delivered in article 2, however those blows probably underestimate the amount of force in a typical blow and certainly do not reflect the types of blows that lead to concussions. Likewise, 10kg is heavier than almost every helmet on the rattan field. Given that concussions are caused by shots that have your opponent’s body mass behind them, we need to resist several hundreds of pounds of force in order to protect against concussions. Against those numbers, 50lbs is completely insufficient to be relied upon for protection and so we cannot rely on a heavy helm to protect us.
That isn’t to say that there might be a few shots where a heavy helm makes the difference between a concussion and no concussion, which might be enough to cause fighters to choose to wear heavier helmets as a personal choice, but the notion that a heavy helm can be relied on to prevent concussions or that a fighter who receives a concussion received one because their helmet wasn’t heavy enough is patently false.
Padding and Suspension Systems:
Aside from mass, the other aspect of helmets that many focus on as a way of preventing concussions is the padding/suspension system that it provides. Here we will address the reasons why neither padding nor suspension systems protect the head from acceleration.
Please keep in mind that the following discussion is focused solely on the protective effects of padding against concussions (i.e. its ability to prevent acceleration of the head). This article does not make the claim that padding provides no benefit; in fact the opposite is true. However, the benefits of padding are limited to reducing pressure. Pressure can cause several different types of injuries to the head (including skull fracture) and is the only factor that influences pain and discomfort, but do not mistake an absence of pain for an absence of acceleration. The experience of pain is separate from the mechanisms that cause concussions.
Padding and Suspension Systems are the Same Thing:
Before we get started, it is also important to understand that padding and suspension systems are functionally equivalent to each other and are also functionally equivalent to springs. In practice, padding is a compression spring and suspension systems are expansion springs, however all springs are governed by the same mathematical functions. We know that padding/suspension systems are functionally springs because:
Padding, suspension systems, and springs all provide progressive resistance to force based on how far they have been compressed
All three have sufficient elasticity to return to shape after they are released
All three convert kinetic energy to potential energy and and potential energy to kinetic energy
the materials used to construct padding and suspension harnesses are themselves springs (i.e. the fibers that make up cloth and batting and the air bubbles in foam are themselves tiny springs).
Padding/suspension system return to their original shape
Padding does not affect the amount of Force experienced by the head:
Consider the illustration provided above. As before, when the weapon strikes, it applies some amount of force, F1 to the padding. As a result of Newton’s Third Law of Motion, we therefore know that F2 = -F1 just like before. If this level of force exceeds the inertia of the padding, then the padding will begin to accelerate towards the head. Now, the reason that it is important that padding functions like a spring is that this allows the front surface (the side closest to the weapon) to accelerate separately from the back surface (the side closest to the head). When this happens, the padding is compressed and the distance between the two surfaces becomes closer by some amount d– the displacement. We also know that according to Hooke’s law, the amount of force required to compress the padding is calculated using the equation F = -k*d where k is the spring constant that describes how stiff the padding is. The materials that are used to pad SCA helmets have relatively low k values, generally speaking, but that’s not particularly important to understanding why padding doesn’t prevent acceleration of the head. When the padding compresses (due to F1), Hooke’s Law tells us that a linearly increasing amount of force is required to compress the padding further. However, for any given moment of time, the padding itself will be attempting to expand by exerting an equal amount of force in both directions. This means that regardless of the amount of compression, the force on the front side of the padding, F2 will always be equal in magnitude (and opposite in direction) to the force on the other side of the padding, F3, or expressed mathematically F2 = -F3.
Given that we know that F1 = -F2 and we know that F2 = -F3, then we know that it is always the case that F1 = F3 and therefore padding has zero effect on the force experienced by the head nor the acceleration of the head.
The Padding Prevent the Head from Moving:
While the above explanation is by itself sufficient to demonstrate that padding has no effect on the force applied to the head from an impact, there will be some who remain unconvinced, and so let me offer an alternative explanation for why padding doesn’t help.
In order for padding to compress, it must have something to push against.
This effect forms the basis of the classic “falling elevator” problem from high school physics. The scenario is as follows: You are standing on a scale on an elevator. When the elevator is stationary, the scale tells you your weight (which is a measurement of force, not mass).
When the elevator goes up, the measurement of your weight will increase because the elevator is applying force upwards that exceeds gravity, causing it to accelerate towards you, which causes the springs to compressed more (which is dependent on the resistance you provide, i.e. your inertia/mass).
When the elevator goes down, the measurement of your weight will decrease because the upwards force applied by the elevator is less than gravity and so the elevator is accelerating away from you. This means that the springs are compressed less, which is what results in the lower weight measurement.
The problem is described in the following video:
So what happens when the elevator is in free-fall? The weight measurement becomes zero.
The falling elevator problem is analogous to the problem posed by adding padding to our helmets. The weapon striking the helmet is the equivalent of gravity in the above scenario while the force applied by the elevator is equivalent to the resistance provided by the head. We can therefore see that when the head is accelerated due to an impact, that the padding doesn’t compress because the head is moving away from it and provides no resistance.
Does Padding “Absorb” the Blow?
There are many who argue that padding reduces force by “absorbing” a blow by compressing. In fact, this argument is incorrect for two reasons: first, it confuses force with energy and second, it fails to understand that the padding won’t compress much during impacts that are likely to cause concussions. Energy and force are certainly related concepts, however energy is defined as the ability to do work and likewise work is defined as the exertion of force over some distance. When you stand on the ground, your body is exerting force (your mass * acceleration due to gravity) but, since you are not moving, you aren’t doing any work and therefore your energy is zero. If you instead stood on a chair, you’d still be exerting the same amount of force (on the chair). You also wouldn’t be doing any work but your position on the chair does represent your ability to do work and therefore you would have an amount of (potential) energy related to your mass, the acceleration due to gravity, and the height of the chair. One of the key aspects of springs is that they convert kinetic energy (KE) into potential energy (PE) when they are compressed. However this conversion is a consequence of displacement. Hooke’s law tells us that the force (F) required to compress a spring is given by the equation F = -k*d, where k tells us how stiff the padding is (i.e. spring constant) and d is the displacement distance. Importantly, this amount of force is also the amount of force applied by padding that is compressed a given distance and this amount of force is exerted in both directions as I pointed out earlier. Determining whether a spring (or our padding) will compress is largely a matter of exerting sufficient force to exceed its resistance at a given amount of displacement. In order for this to be possible, the forces applied to both ends of the spring must exceed this value (or the spring will simply accelerate through space rather than compress). When the padding is compressed, it temporarily stores an amount of energy according to the equation PE = 1/2 k * d2. In practical terms, this means that the padding in our helmets will only compress up until the point where the needed force to continue compressing the spring exceeds the resistance provided by either the head or weapon. This creates a finite set of possibilities:
The padding is stiffer than the resistance provided by the head and does not compress at all before the head accelerates as if the padding were not present.
The padding is soft enough to compress, but compresses to the point where the force to continue compressing the padding exceeds the resistance of the head, at which point he head accelerates as if the padding were not present.
The padding is much softer than the resistance provided by the head and therefore it fully compresses, at which point he head accelerates as if the padding were not present.
If case 1 above is true, then the padding has behaved no differently from a solid object, and so let’s look at cases 2 and 3. As noted above, we specifically need a helmet to protect us is when our head isn’t providing much resistance. Therefore, if case 2 is correct, then we should expect a very small amount of compression, which means that the padding isn’t storing much energy. Likewise, if case 3 is correct, then the k-value of the padding must be very low and so again, the padding isn’t storing much energy. In all three cases, there is a point in the impact where the padding behaves as if it is not present. Furthermore, we can see that the padding’s ability to store energy is directly related to displacement rather than force, and finally, we can see that in all cases, the amount of energy stored by the padding is zero or near zero. That is to say that when we are most at risk for a concussion, the padding doesn’t help.
Does Padding Serve as an Early Warning System?
As mentioned above, the key factor in preventing your head from accelerating is the engagement of your neck musculature. This requires that you either keep your neck engaged at all times (as was suggested by article 4) or be aware of incoming blows and respond accordingly. Ultimately the entire point of a passive protection system is for the times that you fail to do this. In this regard, the fact that padding applies force as soon as it is struck, and that this force is smaller (i.e. only the spring constant of the padding itself), would suggest that ample padding might provide an additional tactile warning system for when vision has failed.
In order for this to work, the padding must allow sufficient time for a response to occur. Human response times to tactile stimuli are in the 150-200 ms range, so that’s how much of an early warning padding would need to give us in order to help us.
It would be nice to have some high-speed camera footage for measuring this; however we can make a good estimate by measuring the length and duration of a fencing lunge. According to Gholipour et al. (2008), a modern fencing lunge covers approximately 1 meter in 1.5 seconds.
Importantly, as noted above, the amount of compression will be negligible and so this won’t really slow down the lunge. While more force is required to compress the padding, blows that can cause concussions already must provide a lot of force, so we shouldn’t expect this to matter. If we assume for the sake of a “best-case” scenario with relatively thick padding that is approximately 5 cm (2”) thick, then we can calculate the amount of time necessary for the lunge to cross this distance as 75 ms. We can also then determine that for padding to provide an early warning system, we would need at least 6” of padding. However, we must also keep in mind that padding, like a spring, cannot compress fully and so there will be some remaining thickness which will cause the head to be struck earlier than if there was not any padding, thus reducing a fencer’s ability to respond to visually seeing that they are about to be struck. However, given that the lunge is several times slower than the ability to respond to visual stimuli (~200-300ms), we likely should expect that this effect is negligible.
The Dangers of Armoring Up:
While the analysis provided above may suggest that we can simply strap large quantities of lead weights to our heads and then hit each other as hard as we like, there are practical and safety limits to the amount of mass that can be added to the head. There is even some evidence in other sports that increased head protection can lead to more concussions. For instance, head gear was eliminated from men’s boxing in 2016 due to the fact that it increased the risk of concussions. This Wired article provides a more detailed explanation. There are ultimately a number of ways that increasing the armor we place on our heads can put us in more danger.
Bigger helmets = more head hits
Perhaps the most important consideration is that by adding mass and padding to our helmets, we make them larger. This creates a larger target, which makes head shots more likely.
Adding too much mass to the helmet puts you at substantial risk for whiplash and can increase your risk of spinal injury
Whiplash is an umbrella term for tears of the ligaments of the spine, tears in neck muscles, and damage to cervical vertebrae that occurs when the neck is hyper-extended (stretched out too much). Adding too much mass to the head puts you at substantial risk of this occurring because it can result in situations where the neck muscles are incapable of stopping the momentum of the combined head and helmet. In extreme cases, this may be sufficient to break your neck. Furthermore, if the purpose of adding mass to the helmet is to prevent concussions when the neck muscles have already failed to engage, then this mass is coming into play precisely when the neck muscles have failed to engage.
Situations that can lead to whiplash injuries include times where the head is moving and the body is not, such as collisions between fencers, falls (especially when falling onto something that stops part of the body and allows the head to continue to move… like a hay bale or another fighter), and in HEMA, grappling/throws.
Increased Mass and/or Padding may lead to Increased Calibration
Increased helmet mass and/or padding will reduce the perception of pain/pressure that result from being struck. This lack of sensitivity may cause fighters to ignore blows that they would have taken if not for their armor, which can cause their opponent to hit them harder. Alternatively given the absence of perceived pain/pressure/motion from hard blows, fencers may be encouraged in their belief that hitting hard is safe because they are wearing armor despite the fact that the sensation of pain and pressure are completely independent of the mechanisms that cause concussions.
Increased Mass and/or padding may Cause you to Fail to Notice that you have been Concussed
The brain does not have any pain/pressure sensors inside of it, so the presence or absence of pain doesn’t tell us whether we have sustained a brain injury, but impacts that can cause a concussion typically hurt. Helmets do a good job of mitigating pain, but as shown above, do not mitigate acceleration to the same extent. As a result of this, heavier and/or more padded helmets can make it harder to tell whether you have been concussed.
It is absolutely vital that fencers who have been concussed be removed from the field as secondary impacts are known to have a major impact on the severity of a concussion and its permanent neurological effects. Furthermore, these secondary impacts do not need to be nearly as hard as the initial injury, so even relatively soft impacts can cause life-altering permanent damage following the initial injury. Because of this, efforts to alleviate the effects of concussions in other sports have focused on improving the ability for coaches, staff, and players to recognize concussions and on building policies that require injured players to be removed from the field. Interfering with a fencer’s ability to recognize a concussion is the worst thing that we can do when attempting to manage concussion risk.
Increased Armor = Increased Mass = Harder Hits:
As noted above, the strikes that are the most risky for causing a concussion are those that combine body mass with acceleration. If fighters increase the amount of armor that they are wearing, they are adding to the mass of their body. If we consider the force that results from a jumping/falling strike, for instance, we can see that adding the mass of a heavy helmet (10 kg as in our earlier example) would increase the force of a blow by around 22 lbs. (10kg * 9.8 m/s2 = 98 N = 22lbs), which nearly halves the effective protection provided by their opponent’s helmet. If we also consider that harder hits will result in fighters wearing additional armor on the rest of their body, the the added mass behind strikes may fully negate the protection provided by the armor in the first place. Therefore, a person who armors up to protect themself, is in fact becoming more of a danger to their opponent. If everyone armors up to the same degree, the equipment becomes progressively more ungainly and expensive to no net benefit.
The Dangers of Misinformation:
Recently the SCA’s marshallate has taken the stance that increased padding will provide protection against concussions. While it is reasonable to expect that helmets (and fencing masks) be sufficiently padded and be in good condition, we have demonstrated here that the padding does not protect against concussions. This kind of misinformation makes us all less safe. Legal Liability:
Participants in SCA combat sign a waiver that indicates that they understand that there are risks associated with participation. However, these waivers rely on the assumption that participants are providing informed consent. When marshals acting on behalf of the organization and more importantly, the society marshals spread misinformation, they are removing participants’ ability to be informed. Furthermore, if it can be demonstrated that these officers should have known otherwise, then it likely exposes the organization to a lawsuit on the basis of negligence if a participant receives a concussion despite the padding in their helmet.
Misinformation, especially misinformation spread by the marshallate’s office may also encourage fighters to feel that hitting harder is safer than it actually is and so it may also be a factor in increasing calibration.
Failure to Recognize Concussions:
Similarly fighters and marshals who are acting on the false belief that increased padding or mass will provide protection against concussions may be less likely to consider that a concussion has occurred and may therefore be less likely to recognize when one does occur. As noted above, failure to remove fighters from the field immediately following a concussion creates a significant danger of permanent brain damage.
Excuses Bad Behavior:
One of the most dangerous effects of the false belief that armor prevents concussions is that it provides an excuse for fighters who are a danger to themselves and others on the field. As we have shown here, helmets cannot be relied upon to protect against concussions and so it is patently false that if a concussion occurs, that it occurred due to armor failure or a lack of padding. In fact, it was precisely this kind of ruling that motivated me to write about concussions in the first place.
In addition to the ways that the false belief that helmets protect us from concussions make SCA combat less safe, there are other problems that this false belief creates.
Unnecessarily Complicated rules:
If fencing masks are going to continue to be legal armor, then creating a separate set of requirements for helmets that cause them to provide a greater level of protection creates a double-standard in the rules and likewise creates an illusion that it is ok to increase calibration when people are wearing helmets.
Acquiring a set of equipment isn’t cheap and adding to the required equipment should not be taken lightly. With 2000 authorized fighters, even the addition of a $50 piece of equipment represents an economic cost of $100,000 for our membership. Furthermore, any increased cost will remove some fighters from being able to participate.
If calibration increases as a result of increased armor, the wear and tear on equipment will represent an additional cost for participation and will also create an increased risk from broken blades, etc.
The requirement or practical necessity for increased armor will exclude participants who are smaller in stature or who have less physical strength.
Helmets do not provide protection from concussions because they do not prevent the head from accelerating. While increased mass does have some protective effect, the effect is not sufficient to eliminate the risk of concussions that occur due to the types of blows that are most likely to produce concussions in the situations where concussions are most likely to occur. Padding or suspension systems cannot reduce the acceleration of the head because they do not alter the amount of force delivered to the head. Increasing the amount of armor in an effort to prevent concussions is likely futile and may increase the risk for concussions and/or other serious injuries.
Most importantly, the marshallate has an important role in preventing concussions. It is vital that marshals understand that armor cannot prevent concussions and that recent statements regarding padding in helmets be revised because this sort of misinformation poses a hazard to the safety of SCA combattants.
Guskiewicz KM, Mihalik JP, Shankar V, et al. (2007). “Measurement of head impacts in collegiate football players: Relationship between head impact biomechanics and acute clinical outcome after concussion”. Neurosurgery 61 (6): 1244–52; discussion 1252–3.doi:10.1227/01.neu.0000306103.68635.1a.
Myers, JL. et al. Early Results of a Helmetless-Tackling Intervention to Decrease Head Impacts in Football Players. Journal of Athletic Training, December 2015 DOI: 10.4085/1062-6050-51.1.06
Gholipour, M., Tabrizi, A., and Farahmand, F. Kinematics Analysis of Lunge Fencing Using Stereophotogrametry. World Journal of Sport Sciences(2008), 1(1): 32-37.
Guskiewicz KM, McCrea M, Marshall SW, et al. Cumulative Effects Associated With Recurrent Concussion in Collegiate Football Players: The NCAA Concussion Study.JAMA. 2003;290(19):2549-2555. doi:10.1001/jama.290.19.2549.
R.C. Cantu. Guidelines for return to contact sport after a cerebral concussion. Phys Sports Med, 14 (1986), pp. 75–83
The last six months of my Free Scholar-ness coincided with a very active time on the Atlantian Rapier Net. New fighters had questions, important questions, so I commented as thoroughly and helpfully as I could. Other fighters were having issues, major issues, so I replied helpfully and considerately and with caution to be as reserved as possible. I thought: “Here is a chance for me to be the Provost I want to be” as my peer had instructed me.
Watching all of this, Ella asked Dante “When does Wistric get to be a real person again?” He told me this at some point.He laughed, I laughed, then I grumbled, then I laughed.
All of this afterall was somewhat out of character. I had made a reputation by stomping on White Scarves’ metaphorical “sensitive anatomical features.” I was energetic and enthusiastic and did not always bother to consider if what I was doing was the best way to go about it. But I was trying to be, seeing if it was something I could do without opening a vein.
At my White Scarf prize, after Dante and I fought and were hugging, I said, “I don’t get to be a real person ever again, do I?” “Nope!”
The Atlantian OWS has open archives. The advice upon joining is you start at the beginning, open a bottle of Scotch, and unplug your keyboard (because you will want to reply). I skipped that. I read the previous year or so of replies. I searched for my name and friends’ names. I read the comments about me and most were spot on. There were a couple I itched to reply to, but for the most part people were right. My favorite comment of all was “Wistric always does everything 120%. Sometimes that’s not a bad thing.”
There seems to be a class of SCAdians to whom that description applies. They want to make themselves awesome and make everything around them awesome. They burn to do it and if nobody else is making it happen they will take it and run with it, usually to the annoyance of those who were planning to get around to making it happen some day. They may not make it happen the right way, but, in their minds, it’s the right way because at least it’s happening, which is more than could be said before (a bad plan being better than no plan at all, as the old saying goes). Usually, the thanks they get is silence at best, and at worst it’s people bitching about how they did it wrong.
These 120% people are rare, but I feel they are one of the best assets available to the SCA (though I could just be saying that because I’m one of them). We do kind of a shit job of husbanding them along (see: previous paragraph).
Many of them burn hot and burn out. They either just run out of fucks to give or they get tired of beating their head against a wall of bureaucracy, tradition, and sloth and go find other hobbies. Some of them stick with it because they love and care about the SCA, so the positives outweigh the negatives.
Eventually they come up for consideration for a peerage (In my case it was twice: the first time around was the White Scarf, which was the closest I’d get to a peerage then, the next time around was the MOD). After wading through all of the obstacles and resistance, and while still struggling against it, they start to realize they’re being watched.Now, on top of all the other stress and frustration, they’re dealing with feeling under the microscope. They’re busting ass, they’re feeling unrecognized, and they know everybody’s watching for any tiny screw up or shortcoming.
They start thinking: “Did I do ENOUGH of that thing? Am I marshaling or winning or being courteous to my opponent enough? Or did I do TOO MUCH? Should I marshal less or fight less or, I don’t know, maybe my courtesy looks contrived and shit? Maybe some people feel one way and some people feel another! Who’s right? Who makes up more of the Order from which I so very much want recognition for all that I’m doing for their community?!”
I’ve been there. Mega-been there.Twice now. I’ve seen others there. Here is where the SCA fails them yet again:
The absolute worst thing somebody who they see as having been part of the problem can do at this moment is try to “help”. This helpful minded soul will likely let their “serious concerns” show through. This “helper” will come off as dickish, critical, and unappreciative. They will make themselves a lightning rod for all of the frustration. Sure, the “helper” may be well-meaning, but they don’t stop to think they may do more harm than good. Of course, they do things the Right Way, so that doesn’t fall into the realm of possibilities for them.
I’ve seen 120%ers fuckup big-time under all that frustration. Then, devoid of sympathy, those who were on the fence or in the way say, “See? Not ready.” Under the most stress a person can experience in the SCA, more stress than the non-120%ers are likely to ever experience, sometimes people fuck up. A 120%er who avoids fucking up under these circumstances impresses me more than any other achievement of a candidate.
My peer had a nice work around: she got all the “helpers” to talk to her (or share commentary in the White Scarf list), got their permission to share it with me, packaged it, and said, “So do this stuff.” I did and it worked. That sort of guidance and protection is the primary reason I decided to be a cadet and stay on as an apprentice to the peer who offered it to me. It’s the primary duty I feel towards my Scholars.
Somebody needs to sit the 120%ers down and explain to them they don’t get to be a real person anymore. Somebody needs to talk to them about what they’re doing wrong. You may not be the best person.
Dante has another good line: “The Gold Scarf was joy. The White Scarf only relief.” When you get that intermediate recognition, it feels great! Yeah, recognition, woohoo! I don’t suck! Before you get it, though, you generally aren’t that worried about it because it’s just a step on the path. It’s just an attaboy.
The ultimate award is different. Being recognized by the arbiters of the Right Way, the judges of excellence? For people of a certain personality, that’s a huge source of stress. They look up to those peers, they’re striving to be like those peers (and, probably, striving to surpass them). Some of those peers are their heroes.
If, at this point, you’re smugly dismissing anybody who feels this way as “Just in it for the cookie,” you are part of the problem. The awards aren’t cookies to be chased – that you see them as such means that you think of the awards the wrong way and your criteria for assessing candidates is at least moderately flawed. Our awards are awards, not rewards. Our awards recognize excellence and express gratitude.
One day, hopefully, the 120%er gets that recognition and they stand before their kingdom shoulder to shoulder with their heroes. They wake up the next morning and they no longer think “Am I doing it right? Who’s saying I’m doing it wrong? Am I doing harm to myself or my kingdom right now? What more is it going to take?” For days after I got my white scarf, I giggled and cackled anytime I saw it. That period was only slightly shorter after I got my collar. I laughed out of joy, but also out of sheer lightness of spirit.
Personally, I don’t care if a candidate fucks up. I’m not in a position to throw stones on that count. I care why they fuck up. There are ways to fuck up for the right reasons; ways that make me no less certain that that candidate can and will do the job of a peer, and do it awesomely. Motive matters.
I have a standard vigil talk. For those who fuckup with good intent, there’s additional vigil talk: “You don’t get to do that thing you do anymore.” You don’t get to be a real person. Sorry, sucks. You can still say no. When they wake up the day after their elevation, though, I believe it will be easy for them to never do that thing again because I believe they want to do good and they now know a thing that they do that does ill. If I didn’t believe they wanted to do good, I wouldn’t poll for them and I wouldn’t be at their vigil. Motive matters.
So how do we foster these bright fires? How do we keep them stoked while making sure they don’t burn it all to the ground? We start by listening to them.
If they say “I think we should do X,” we can respond in a number of bad ways:
“That’s not our tradition.”
There’s a right way to disagree with them: “I don’t think that’s the best plan, here’s why (Here are the negative effects it will have on the community and on the kingdom).”
If they say “I think Y is a problem,” there are bad ways to respond to that, too:
“No it’s not”
“That’s the way we’ve always done things”
If you don’t think it’s a problem, explain why. If they point out ways in which it’s causing harm, be able to explain why it’s not actually causing harm, or be willing to discuss other ways to address that harm. If you want them to be able to tuck their ego away, you have to do the same.
If we respond with silence or indifference, we can only blame ourselves when they take action. Frankly, they cared about our community and our kingdom more than we did. That’s our fault.
The more we come down on somebody for taking action to make the community and the kingdom better, the more likely we are to be viewed as malicious and malignant. A person who wants to do good does not care what a malicious person thinks; don’t be surprised if the person you’ve criticized for doing good ignores your future criticism. You definitely can no longer “help.” You are an asshole (I want to add a disclaimer that that’s just the way THEY think about you. But I won’t).
If they fuckup, we need to attempt to be understanding. Moral absolutes are detrimental when the offense is “he hurt my feelings” or “she stepped on my toes.” Motives matter.
We have people in the Society whose motive is to make the Society the best thing it can be. We fail them on a too regular basis. We make our Society worse when we do. That is to our shame. Perhaps we should stop.
When members of the arts community penalize somebody for saying “I want to be a laurel” what they’re saying is “You’re not supposed to aspire to stand with your heroes.” How much more soul crushing can you get?
Physical measure is the largest space between you and your opponent where you can land a single tempo blow. Ex: a lunge
Effective measure is largest space between you and your opponent where you can land a single tempo blow while your opponent is defending themselves.
This distinction is very important. When fencing, there are many times where you can reach your opponent, but they are far enough away to be able to defend themselves, and you put yourself at great risk for a counter attack.
Many considerations go into both physical and effective measure, and those factors carry different weight for each fencer. Some examples include height, wingspan, speed, acceleration, efficiency of motion, positioning, processing time, reaction time, and focus, just to name a few. However, that is an entirely different can of worms that I will not currently get into.
Some of these factors are immutable such as height and wingspan. Other factors can be trained like technique and speed. Finallysome can be fluid within a single moment such as reaction time and focus. When considering effective range, you must be aware of as many factors as possible of both you and your opponent to give you the best chances possible to be successful.
Many people operate well below what their maximum range potential is. As I said many of these things are trainable. Speed and acceleration can be trained through a variety of exercises. I recommend the standing long jump, and leg presses. Technique which I referenced earlier refers to correct and efficient motion. For example, hand before foot when lunging and keeping a relaxed shoulder when extending. Good technique (decision making aside) requires smooth motion. That smoothness eliminates all unnecessary muscle twitches, jumps etc. which slow your movement and decrease your acceleration and in turn your effective measure.
The mental skills of reaction time and focus are much harder to train. The best way to train reaction time that I have found is to expose yourself to all possible motions from specific positions. The more you know of what your opponent is capable of from any given position then you won’t be surprised by anything allowing yourself to calmly react to whichever choice that they made in a much more efficient manner than analyzing their attack on the fly, and making a guess as to what their goal is. Focus is hard to train. The best drill I have found is also the best one to explore physical and effective distance.
This is a single sword drill without use of the off hand. Fencer A starts as the leader, and B as the follower. Fencer A places themselves where they think they can strike B in the torso with no defense from B. This is repeated until A successfully finds the proper range. That range is the extent of their physical measure. The goal then becomes for A to strike with one tempo while B defends. A may move their blade and posture at will, but may only lunge once. B may defend with their blade at will and may retreat once, but retreat admits defeat if A hasn’t lunged. Upon failure A moves 3-6 inches closer. This is repeated until A is successful. Upon Success A moves back 3-6 inches. This repeats for 5 minutes or so and hopefully a small range of less than a foot has been established of A’s effective range. They then switch roles and start the process over again(remember to hydrate). Strategies to employ in this drill are explored below.
There are ways to change effective measure. One way to do this is with an effective feint. By feinting you can either change your measure with a gathering step, threatening a line, provoking an attack, or any combination of those. For simplicity’s sake we will use the example of threatening a line. Starting at physical measure, imagine yourself threatening a line. Your opponent puts herself out of position with a wide parry. At this point you have now changed effective distance, due to her poor positioning and inability to defend a second threat. You are now able to disengage around her blade and strike her in a single tempo. By merely moving your blade into a threatening position you have the ability to change effective measure.
Another simple way to change your effective measure is with your body language. If you present yourself as fully engaged, tensed, and highly reactionary your opponent will naturally feel threatened to a degree and keep their guard up. However, if you look relaxed and lackadaisical they will often follow suit. With this reduced focus it is very possible to slip through their defences with a slow extension that looks like a probe into a quick full lunge. This is not always going to work, but it has the potential to if you know your opponent is weaker mentally, or is taking you lightly.
Gaining a dominant blade position is another way to change effective measure. Imagine yourself lunging straight at your opponent and her being able to parry it successfully. With these factors as givens you are not within your effective measure. Now change the scenario to where you place your blade over theirs and lunge forwards. By lunging in a way that captures their balde in the process you render their parry useless. However, if the opponent chooses to retreat as well as parry often you will still fall short. This is a little bit of a conundrum since if they choose to only blade parry they are within your effective measure, but if they also retreat then you are not within effective measure. In this case your effective measure is directly dependant on the way in which our opponent chooses to defend themselves. The many factors of effective vs. physical measure are complex, fluid and can change mid fight. However, understanding them is crucial to being a successful fencer. Start calculating both the physical measure of yourself and your opponent the moment you know who you are facing. Then when the fight begins try to learn all you can about their reactions, speed, and how they choose to defend themselves. By gaining this knowledge you are better informed to make a good attack, and to stay outside of their effective measure.
Over the past few months I’ve been running a survey of SCA rapier fighters. As the title suggests, it contains mostly random and seemingly un-related questions.
This survey set out to test a series of ad hoc hypotheses encountered in the rapier community and to answer certain questions. As of this writing I’ve received 391 responses. Thank you all for participating and humoring me. Unfortunately, today is the slightly less interesting demographic analysis. In future weeks I’ll discuss what those hypotheses were and the results of testing them.
None of the results should be considered definitive or even particularly well-collected and well-analyzed. I leave such quality collection to the professionals.
If there are any questions that might be answered by the data that you might have, please let me know and I’ll see what’s available.
Gaps in the data collection
In retrospect, I should have captured information regarding age, time in the SCA, and time fencing in the SCA. The lack will be noted in discussion as we go (frequently. So frequently).
As a supplemental data source for the analysis, we have the Society level rapier authorization stats for Q2 2016.
As of this writing I have received a total of 384 responses. Table 1 shows the breakdown by kingdom, what percent of the total each kingdom accounted for (kingdom response/total responses), and what percent of each kingdom’s authorized fighters participated (kingdom response/authorized fighters)
Percent of respondents
Kingdom Participation Rate
To understate the matter, participation rates varied greatly. Nearly 50% of Meridies (the kingdom of the survey author) participated. This rate was 5 times the Society-wide participation rate. On the other hand, other kingdoms participated at a rate only a third that of the Society-wide rate. In some areas of the analysis I may use that ratio to determine weighted responses. Maybe.
Of the respondents, 48 were Masters of Defense. 93 were White Scarf or an equivalent. On the other end of the spectrum, 133 had received no rapier-related award yet.
Table 2: Award Response Rates
Baronial/other regional rapier recognition
Master of Defense
Order of high-merit (White Scarf, OGRe, MOB, Bronze Ring, Queen’s Blade, etc)
Order of Merit (AoA or equivalent)
That is a spectacular amount of participation by our newer fencers, and is greatly appreciated.
Rank by Kingdom
More analysis, this time comparing kingdom responses and rank to determine where that newer fencer participation came from, and where the lower ranks were not as represented (Table 3).
Table 3: Rank by Kingdom
Baronial/other regional rapier recognition
Master of Defense
Order of high-merit (White Scarf, OGRe, MOB, Bronze Ring, Queen’s Blade, etc)
Order of Merit (AoA or equivalent)
Percent AoA or less
A quick look at this notes that there are a couple of kingdoms, especially in the northwestern portion of the United States, where the data is going to be even less accurately representative of the community. Of course
As shown in Table 4, 110 respondents were female, 384 male, 4 non-binary, and 5 did not disclose.
Table 4: Gender response rate
Here is a point where having the age and timeframe criteria would be useful:
Aethelmearc’s survey showed their population to be 30.5% female, 69.5% male. The findings (28.9% female, 69% male, 1% non-binary) are in keeping with this finding so it may be that Aethelmearc’s findings can serve as a reasonable approximation of the Society in some matters, especially those around the relative proportion of new male and female participants, differences in the rate of advancement for male and female fighters, and rate of loss of male and female fencers.
The Aethelmearc survey, for its part, found no significant difference in gender tenure until after 7 year mark (34.8-36.2% female for 0-6 years, 20% female after). Whether this drop-off is society wide or a result of sampling number and whether it has continued in the past four years are, I believe, data points that would help our community continue in its development to serve all fencers better.
Gender vs. Rank
The Aethelmearc survey seems to also have not calculated the gender vs. rank rates. As noted above, having this information (and the rate of advancement by gender) would be useful knowledge. Table 5 shows the current state of the Society, but only a snapshot that is not on its own definitive.
Table 5 Gender vs. Rank
Master of Defense
Order of high-merit (White Scarf, OGRe, MOB, Bronze Ring, Queen’s Blade, etc)
Order of Merit (AoA or equivalent)
Baronial/other regional rapier recognition
As has been discussed in many fora, the proportion of female MODs is much lower than the proportion of female fencers. This topic could, and possibly should, be the topic of its own survey (one conducted in a more serious manner than this).
Thus ends the demographics discussion. Future installments will cover the the actual assumptions challenged, hypotheses tested, and questions… questioned, and what the data revealed.
(Ed. This is part 4 of a multi-part series. Comments that indicate a failure to read previous entries shall be mocked and, possibly, moderated with extreme prejudice. The author took the time to do the research, you can take the time to read it)
(Part 1Part 2Part 3)
In the previous articles, I described the amount of force necessary to cause a concussion (Part 1), the force levels from a typical blow (Part 2), and other sources of force that can contribute to concussions (Part 3). In part 4, I will describe a set of techniques that will help you to both avoid concussing your friends and avoid being concussed yourself. Fortunately many of these techniques are also important aspects of good fencing in general. They will largely focus on the core mechanics of your fencing and will generally require active practice in order to put into regular use.
How not to concuss your friends:
The number one way to prevent concussions is to minimize or eliminate blows that land hard enough to cause a concussion. As the person delivering the blow, the key to keeping yourself from concussing your opponent is having control over your own weapon and body. Maintaining this control is largely a matter of practice; however there are certain techniques that will make it easier to keep control over your motions, and you should focus on using these techniques. First and foremost,Train good technique regularly. It is important to practice such that your technique is good even when you’re tired. Furthermore, consistency is a product of practice. If your lunge varies wildly in its length, how can you possibly have any idea how hard you’re going to hit someone who is standing within that range?
In general, you should hold your body upright and keep your arm and body relaxed and flexed, not tensed. You should also keep your core musculature engaged, tuck your tailbone, and support yourself with your legs planted firmly on the ground.
When you are moving, you should push yourself with your legs. Move forward by extending your rear leg and move backwards by extending your front leg. Your shoulders and hips should remain parallel to the ground and shouldn’t rise or “bounce” when you move. Likewise, don’t “fling” your body weight into the motion and allow the rest of your body to follow. In both of these cases, you are engaging in a motion where you spend a period of time falling and where it is impossible to control the placement of your body weight. Maintaining this safe technique is largely a matter of keeping your tailbone tucked, your core engaged, and taking small steps.
When striking your opponent, you should be certain to extend your arm completely before the rest of your body moves (without locking your elbow). If your arm is still in the process of extending when you strike your opponent, it is impossible for you to adjust or cushion the blow if needed.
As with your footwork, it is also important to push your sword forward rather than punching with it. Your movement should be similar to a waiter extending a tray. Punching and flinging motions are more likely to result in a hard hit because they offer less control over the muscles that are recruited. These motions also strike with a lot of impact force (i.e. with a “pop”), which makes it less likely that the sword will flex. Wistric recently suggested bare-knuckled lunges (with your fist rather than a sword) against a brick wall as a method for testing this mechanic. If this idea gives you pause, then it is likely that you lack control over your technique. If it hurts,then your technique is unsafe (and you’re hitting your opponents that hard over an even smaller cross-section. How do you think that makes them feel?).
Cuts should be delivered from the wrist, shoulder, or a sequential combination of the wrist and shoulder (only one moves at a time), not the elbow. This is better technique for a variety of reasons, however from a safety perspective, this prevents the kinetic linking that is typical of blows from armored combat (but is wholly unnecessary for cutting with a sword). It is important that you avoid using your hips when you cut.
Once the arm is extended, reaching your opponent should be performed by moving the body and/or legs. These motions should also be performed by pushing yourself forward. Do not jump.
If necessary, you should begin cushioning the blow immediately after impact (If you are striking with a technique that causes it to be necessary to cushion before impact so that you don’t hit too hard, you need to re-read the section on how to strike). As noted above, this will be impossible if you are tensed or if the arm is still in the process of extending.
It is best to cushion thrusts by withdrawing the arm in a straight line past your body (i.e. by reversing the motion of the extension). This method will provide the greatest range of motion for cushioning the thrust and removes the weapon from its position between you and your opponent where it can become grounded on your body. Other methods of breaking the force of a thrust such as releasing the ring and pinky fingers and breaking at the wrist in order to carry the weapon down or to the sides can cause the pommel to land ground itself onto your leg or chest which can result in an extraordinarily hard hit if your opponent is falling, slipping, or completely fails to control their body movement. While these situations may not arise due to your actions, you still have the ability to prevent their injury and should do so if possible.
Cushioning cuts is simply a matter of breaking the motion at a joint. The best ways to break a shot are by releasing your pinky and ring finger or by breaking at the wrist. These this will limit the mass behind the impact to only that of the sword and hand. This smaller mass should be less than the mass of the head and so due to the relative difference in inertia, it is the weapon rather than your opponent’s head that will undergo acceleration due to the force of the blow. In situations where breaking at the wrist is not possible, breaking the impact at the elbow or shoulder should be sufficient.
As fighters, it is also worth considering that there are sometimes blows that you shouldn’t throw even though it would be legal to do so. This is largely a matter of judgement and it is worth considering that it will sometimes be very hard to override your competitiveness in order to protect your opponent’s safety. These situations may occur for a variety of reasons. For instance, if the ground is slippery, you may need to refrain from lunging because you can’t be certain of how you will land. It may also be prudent to change how you target your blows such that you avoid hitting people in the “danger zones” for causing a concussion or to be gentler when striking these areas. For instance, in melees, it might be best to avoid blindsiding someone with a thrust to the temple, even though it isn’t against the rules.
The above list is somewhat convoluted, and not all of the techniques can or should be enforced by the marshallate. However, there are a couple key mechanics that marshals should keep an eye out for. Ultimately fighters who routinely:
1) Punch with the sword 2) Fail to extend their arm completely before moving the rest of their body 3) Throw themselves forward or jump at their opponent 4) Fall down or slip 5) Use their hips to generate force on a cut
Should be targeted for correction. These fighters are a danger to others and, if they refuse to alter their mechanics to correct these problems, they should be removed from the field.
How not to get concussed:
While it is important to understand that the blame for a hard shot generally lies with the person who is delivering the blow, there are a number of techniques that allow the recipient of a blow to do so more safely. Because of this, it is worth considering that a fencer who consistently fails to perform these techniques is a danger to themself.
Awareness – Fencers should be aware of when they’re about to be hit, especially in melees. Fighters who can’t see shots coming cannot protect themselves from injury and should be removed from the field.
Brace for impact – When a fencer knows that they are about to be struck in one of the danger zones, it is possible to brace for impact. This can be done by pushing their head into the blow with their neck muscles and by tucking their chin. Importantly, this is an active use of the neck muscles: Do not tense.
Keep your eyes open – Train to keep yourself from uncontrolled “flinching” at moment of impact and keep your body relaxed. Never turn away from a strike, as this exposes parts of the mask not designed to take a shot.
Maintain good muscular tone in your neck – Your neck muscles are the primary method of resisting impacts. When you are fighting, you should maintain good muscular tone in these muscles so that you can resist impacts even when you are surprised. This is difficult to accomplish, as those who lack body awareness will be incapable of even feeling what this is like. Fighters should engage in routine exercise and practice until they are capable of this. Fighters who are frequently “bobble-headed” are generally failing to do this.
Defend yourself – Don’t rush your opponent without defending yourself. Carefully evaluate how you are performing your “heroic sacrifice to take out the MoD” in melees.
Avoid “bouncing” footwork, “flinging” your body forward, and “jumping” when you lunge. You will be unable to control your body during the falling portion of these actions and if your opponent strikes you during these motions, your body weight will add significantly to the impact force.
Wear a mask that fits – Many fencers have masks that are too large. A correctly fitting fencing mask should result in a slight change of voice pitch. A mask that is too large may in some circumstances, act as an additional lever and make a concussion more likely.
Improve your level of Fitness – There are numerous risk factors for concussions that are related to general health and well-being. Smoking, high blood pressure, obesity, unmanaged diabetes, stress, dehydration, and age all place you at an increased risk for receiving a concussion (Because these result in your brain shrinking slightly such that it has more space to bounce around inside your skull). Some of these can’t be helped (you’re not getting any younger), but if you’re worried, you should take care of your health, stop smoking, engage in routine exercise, practice hydrating, etc.
Wear a mouthguard – There is some evidence that mouth guards may provide a slight protective effect against concussions for football players. Mouth guards are cheap and might not be a bad idea if you are particularly prone to concussions or getting hit in the face.
Do not tolerate dangerous technique – Leave a paper trail when bad things happen. If a same fighter is consistently a problem, deal with them mercilessly. Be aware of your kingdom’s marshallate procedures and policies. If you diverge from procedure, your KRM may be unable to take action.
Recognizing fighters who are placing themselves in danger is perhaps even trickier than identifying fighters who pose a hazard to others. In general, marshals should look out for and attempt to correct fighters who frequently: 1) Charge without defending 2) Throw themselves towards their opponent 3) Are surprised by being hit 4) Freeze, Flinch, or otherwise tense their body before impact 5) Receive hits like a sack of potatoes (i.e. fail to actively resist hits) 6) Are “bobble-headed” by face and chin shots
This past Saturday I taught a class on drills (and other ways to improve) on your own and with a partner. My notes are below, and the drills covered are linked here. One day I should get video of these.
First, GOOD DRILL PRACTICE:
Don’t try to win the drill (ffs!). If your job is to get hit, you get hit. Practice the action.
Start slow and large, train up to small and precise. 80% success rate (4 out of 5). If it’s below that, go slower and larger. If it’s above that, smaller and faster.
Targets should be small (hand, not chest)
Add footwork when it gets too easy.
Drill for 15-30 minutes at practice. If you have a two hour practice, this still leaves an hour and a half for fighting. Fighters will just get bored after 5 minutes or so, so alternate drilling different actions (feel free to cycle back to the first drill). Add time for conditioning on top of the drill time.
Execute an action until it can be done consistently before moving on to the next.
If you’re the coach, take this time to work on your form. Make sure your en garde stance is solid and your footwork and sword-work are clean.
Go slow to go fast. Train at Tai Chi speed to develop the muscle memory. Don’t train going as fast as you can. Train doing it right.
If you’re missing, your hand is going after your foot (point control is a myth).
I use a target of four small pieces of duct tape. One for each shoulder, the face, and the torso at “en garde” height. Start with just hitting one, then just hitting the next, and so on. Once consistent, start rotating through the targets or randomizing them.
Break it down into separate pieces: Start with the extension to strike. Step back half a step to add in the extension and shoulder rotation. Step back another half step to add in the torso lean. Step back another half step to add in a small lunge step. Step back another half step to go train the full lunge. Again, repeat each step until it can be done consistently before moving onto the next. Start over from the beginning each day.
Falling into a rhythm of lunge/recover/lunge/recover is bad. Don’t do it. I recommend using the Random Timer app for your smart phone if you have one. Set the interval to beep between, say, 3 and 6 seconds. Lunge when it beeps. Recover when it beeps again.
The next best use of your solo time is working on your conditioning: Develop the fast twitch muscles of your arms and legs (the ones responsible for bursts of energy), work on your core strength so you can stay in guard a long time, and cardio. These can be worked with mostly bodyweight exercises, no gym needed. Look around for examples (or maybe Dominyk can post some links here).
Also, Hell Drills. Misery loves company, so try getting your whole practice to do these.
Dead time training:
We have a lot of dead time in our lives. Use it to train.
Do footwork around the house instead of normal walking.
Practice standing in guard in line, waiting for the shower to warm up, on telecons, whatever
Hold your sword extended out to the side at shoulder level while watching TV.
“I want to be able to do a thing.” Drill doing that thing. Literally, “My dagger parries to the high inside line don’t work.” Have somebody lunge at your left eyeball until you can parry it effectively. Then add footwork (you or them leading the footwork). Have them add a setup (feint to the low-line, sword beat, whatever).
If you can’t find anybody to drill with you, do directed sparring: Drill doing a thing against an opponent who’s actively resisting (because they don’t know what you’re working on). You will eat a lot of sword until you get it right. Ego impedes improvement.
(Ed. This is part 3 of a 5 part series. Comments that indicate a failure to read previous entries shall be mocked and, possibly, moderated with extreme prejudice. The author took the time to do the research, you can take the time to read it)
In the previous two articles, I demonstrated how the typical amount of force delivered by SCA rapier thrusts relates to the force required to cause a concussion. Importantly, the levels of force delivered against Llwyd’s machine (~15-28lbs) were significantly lower than this threshold (~100lbs). However, we know that concussions do occur from blows delivered in SCA fencing. Consequently, we must therefore conclude that these blows are either delivered with an atypically high level of force, that Llwyd’s machine is not measuring typical blows, or that there are other factors that add to the amount of force delivered in order to reach this threshold. Here we discuss those other factors which include the angle and location of impact, the body movements of the fencers, and the technique used to deliver the blow.
Impact Location and Direction:
The largest factor that determines whether a blow can cause a concussion is where and how it lands. Obviously a blow that doesn’t strike the head won’t cause a concussion, but where a blow lands on the head is also important for determining whether the head undergoes linear or rotational acceleration. As we showed in the first article, far more force is required to cause a concussion due to linear acceleration (~750 lbs) whereas rotation can cause a concussion with far less (~100lbs).
As shown in Figure 1, the blows that are most likely to cause rotational acceleration of the head include rising blows landing under the chin, rising blows to the top of the forehead, and cross-wise shots landing on the cheeks or temples. These blows are more likely to cause rotation of the head due to the asymmetrical shape of the head and the placement and shape of the neck muscles that resist this kind of motion.Specifically, the shape of the head means that the face is further from the axis of rotation than the rest of the head, which provides a longer lever arm for blows to act upon. Likewise, the muscles that resist this kind of motion are the sternocleidomastoid which is relatively small and is not directly aligned to oppose this kind of motion.
Figure 2: Location of sternocleidomastoid muscle. Image from Wikipedia.
The second biggest factor is likely the body movement of the fencers. The blows discussed in the second article were measured against a stationary machine under relatively “perfect” conditions. During a bout, fencers are typically moving and they may accidentally put their body behind blows by using poor technique for delivering a blow such as kinetic linking (i.e. throwing a rattan blow), flinging their body forward in their footwork, jumping, or falling (See Figure 3). Importantly it is possible for either fencer (the blow deliverer or the blow recipient) to add force through body movement.
Figure 3: By throwing his body into the air, Wistric is adding a lot of force to the impact he’s about to receive when he lands on David’s sword. Image from Wistric’s Facebook.
The relative contribution of body movement should not be underestimated. Consider how much force is generated by a person walking into a wall. If that person’s mass is 100kg and they were walking forward at a pace of 1m/s (a moderate walk), then we can calculate this amount of force as long as we know how long it takes their body to stop (i.e. the amount of force is reliant on the rate of deceleration). Due to Newton’s third law of motion (When one body exerts force on another, the second body simultaneously exerts an equal and opposite force on the first), when you collide with the wall, it exerts an equal and opposing amount of force on you, which causes you to stop (i.e. decelerate). Therefore, the faster you stop, the harder you hit the wall (Assuming the wall doesn’t move). Consider a relatively slow stop, taking 0.5 seconds; we can calculate the force as F = 100 kg * 1m/s/0.5s = 200N ~50 lbs. In contrast, a relatively fast stop, taking 0.1 seconds, would result results in F = 100kg * 1m/s/0.1s = 1000 N ~250lbs. Based on this, it is easy to see how movements of the body can dramatically increase the force of impact that can occur well beyond the forces measured by Llwyd’s machine.
Punch vs. Push:
Another factor is the temporal characteristics of the impact. The muscles of the neck provide a significant level of protection against concussions because they are able to resist rotational movement of the head. However, these muscles need to constrict in response to an impact, which takes time. Because of this, impacts that cause force to be applied faster are more dangerous than impacts that spread that force over time, regardless of whether the total force or the maximum force is higher in the slower impact. For instance, a “punching strike”, which maximizes impact force is more dangerous with a blunted weapon than a forceful push because the push provides time for the neck muscles to resist the motion.
That being said, pushing through your target is better technique when using a sword. Swords do not rely on their impact in order to cause damage, rather they do their damage as a result of continuing to cut through a target after the impact. Maximizing impact force, as we might do in boxing, is therefore detrimental because it is more likely to cause the blade to bounce off of the target following the impact and it prevents continued penetration with the blade. This boxing video does a decent job of describing the difference between punching and pushing and the reasons that he gives for why a “snapping” is best for boxing and are the precise reasons why they aren’t good for when you’re using a sword.
This test cutting video, while a bit long-winded, provides an example of how this works with a sharp sword. The rest of the video tests out a couple different ways of delivering blows and is worth a watch, but for our purposes, you can skip ahead to the 20:34 mark.
If we look at the list of other factors listed above, the key take-away is that the person delivering the blow is largely responsible for causing concussions. While they do not have control over whether their opponent steps into the blow, they are in control over:
How hard they strike
The placement of their blows
The technique used to deliver their strike
Throwing their body-weight into the blow and
Their own body movement towards their opponent.
We should therefore consider it the responsibility of the person delivering the blow to control their weapon such that they are not likely to injure their opponent. Importantly, punching and flinging techniques, slipping on the ground resulting in hard hits, failure to control distance, failure to cushion blows, throwing cuts as punches, etc are a form of negligence and as fighters and as marshals, we should be proactive in eliminating these from the field.
Fighters who do these things may be quite capable of delivering blows within the typical force range most of the time, however, these techniques make hard, injurious hits more likely because they remove the fighter’s ability to control their weapon and body. When such blows occur, they are not accidents; they are the result of malice, ignorance, or negligence and should be treated as such.
We should also keep in mind that the recipient of a blow has some control over whether or not they will be injured. The recipient has control over whether they step forward without protecting themselves (i.e. closing the line/parrying, etc) and certainly should avoid footwork that involves flinging themselves forward. Recipients can also control how they receive a blow, but it is not strictly their fault if they receive a hard blow wrong. We should actively train fencers to receive hits correctly and fighters who routinely fail to actively receive blows are a danger to themselves.
The next article will address specific techniques for both the deliverers and recipients of blows to reduce the likelihood of concussions in SCA rapier.
(Ed. This is part of a 5 part series. Comments that indicate a failure to read previous entries shall be mocked and, possible, moderated with extreme prejudice. The author took the time to do the research, you can take the time to read it)
Knowing how much force is required to cause a concussion doesn’t tell us much if we don’t know how hard we are hitting. Fortunately Master Llwyd Aldrydd has created a machine for measuring the force generated by thrusts and has used it to acquire several hundred data points including blows from single-handed rapiers, two-handed swords, and rapier spears. The data he collected is available here for download as an excel document. The analyses presented here were carried out using the data from Pennsic 43 (.xlsx file download) combined with the “second” data collection.
A total of 78 fighters delivered a total of 1275 blows using a variety of weapon and blow combinations. Specifically, fighters delivered as many as 3 blows of each of the following types:
Single-handed strike with a rapier
Single-handed strike with a two-handed sword
Two-handed strike with a two-handed sword
“Harpooning” strike with a two-handed sword
“Fixed hands” strike with an Alchem rapier spear
“Pool cue” strike with an Alchem rapier spear
“Controlled combat” strike with an Alchem rapier spear
However, not all fighters completed all of the different types of blows. The weapons used varied between individuals. For our purposes here, we will focus on only the single-handed strikes with a rapier. A total of 73 individuals delivered 3 strikes with the rapier, for a total of 219 measured impacts.
Descriptive Statistics of single-handed Rapier strikes
Std Dev (lbs)
The first step in determining what a “typical” blow is like is to explore measures of centrality. In most cases it is sufficient to look at the mean amount of force, which we can see is about 21 lbs. However, median and mode are other measures of centrality that should be considered when trying to figure out what is “typical.” It is frequently the case in statistics that we assume that data follows a “normal” or “gaussian” distribution, in which case, mean, median, and mode should have the same value. If we look at the data above, we can see that both the median and mode are 20 lbs, which is pretty similar to 21 lbs. I have also chosen to show the descriptive statistics for each of the 3 blows separately because it helps to demonstrate that the “total” is, on its face, representative of the three separate blows.
The next step is to look at how much variance is present in the data. For instance, it is possible that one fighter (or group of fighters) were hitting with 5 lbs while another fighter (or group of fighters) was hitting with 35 lbs of force. Or, alternatively, everybody could be hitting with 20-21 lbs of force. These two situations are very different from each other, and so we need to determine how “wide” our expected window of force should be. A simple method for inferring this is to look at the range. We can see above that blow force ranged from 5 – 40 lbs. This value doesn’t really help us to determine whether 5 lb or 40 lb blow were common nor does it help us to determine whether most fighters were hitting with around 20 lbs of force, so instead we need to use a different measurement such as standard deviation. What standard deviation tells us is how much of a difference from the average to expect. The standard deviation in the sample shown above is around 7.5 lbs, which means that we would expect most blows to land in the range of 13.5 lbs – 28.5 lbs.
The standard deviation is, however, still a rather blunt instrument because it does not take into account the shape of the data. A good way to see the shape of our data is to make a histogram that shows the frequency of each quantity of blow force (Figure left). From this graph, we can see that most of the blows did occur within the 13.5 lb – 28.5 lb range centered around the average, as we might have expected.
As noted above, it is typical to assume that data fits a normal distribution for the purposes of modelling, but that isn’t always true. In fact, if we overlay our “Observed” data with what would be “Expected” from a normal distribution, we can see that it looks similar (Figure center), but that it doesn’t fit perfectly (Figure 1 middle). Now, we don’t expect that observed data will ever be perfect, so rather than just looking to see if they visually match, we can also do a statistical test called a chi squared goodness of fit test. If we do so, we find that X2(6) = 15.26,p < 0.05, which means it is statistically unlikely that our observed data follows the normal distribution.
I have also generated a third chart (Figure right) that shows how frequently a blow occurs at or below a given force level. From this we can see that 80% of blows fell over the range of 10-30 lbs and that 60% of blows fell in the range of 15-25 lbs, which helps to illustrate precisely how much more frequently blows were to land near the mean than they are at the extremes.
What does this all mean? For starters, the data demonstrate that typical single-handed blows fall within a range of around 15-30 lbs, which is significantly lower than the force that we calculated to be required to cause a concussion in our previous article. However, we know that concussions do occur as a result of single-handed rapier blows and so we must conclude that 1) fencers hit harder during actual sparring than they do when delivering blows against the machine and/or 2) other factors lead to concussions in SCA fencing.
Additionally, the shape of the distribution of blow force supports the idea that fencers are exerting control over the amount of force that they are delivering. Fencers were more likely to deliver a blow that was similar to the mean and less likely to deliver a blow at the extremes than we would expect if the data followed a normal distribution, which suggests an active selection towards the center, which is encouraging. However, we should keep in mind that some of this tendency towards the middle may be due to the limited range of the sample distribution. It was physically impossible to deliver blows with negative amounts of force, for instance, and so, compared with the normal distribution, the probability of low-force blows is lower in our sample.
This dataset may also provide us with another way of measuring an “excessive” blow. Currently the rules define an “excessive” blow as one that causes injury. This is problematic for a number of reasons, but the obvious one is that it is reactive rather than proactive and waits until after an injury has occurred to set a boundary. It also sets us up for having more injuries. As you can see above, the amount of force delivered by a blow is distributed over a range of forces. If we were to increase the mean while keeping the standard deviation the same, we would expect that the number of hard blows would increase. Similarly, if we were to increase the amount of variability (standard deviation), reflecting reduced control, while keeping the mean the same, we would also expect that the number of hard blows will increase and of course, if we both raised the mean force and increased the variability, we would expect an even greater increase in the number of hard blows. By setting the threshold for an “excessive” blow as one that is injurious, we are creating a situation where the marshalate lacks the tools to curb an increase in mean force and/or the variance.
Rather than defining an “excessive” blow as one that causes injury a better method may be to define an excessive blow as one that is atypically hard. I expect that in practice, this is how calibration is handled by most combatants and marshals. This approach has the benefit of actively driving calibration towards the mean, and this practice may be responsible for the shape of the data seen here (specifically the greater tendency towards the mean than in the normal distribution).
If we were to use this approach, the next step is to figure out how to define a shot that is “atypically hard.” We can handle this in a number of ways, however two simple approaches are as follows: First, we can calculate whether a blow is likely to reflect the sample distribution and set a threshold value that dictates that the top x% of blows are considered to be excessive. In statistics, a threshold of 5% is frequently used, which would reflect a blow with approximately 38 lbs of force in the current sample. Second, we can treat the problem as a form of outlier detection. In this case, a solution such as the six-sigma method whereby blows that land 6 standard deviations or more above the mean are considered to be excessive. Using the current sample, this would reflect a blow with 66lbs of force. It would be interesting to devise a method to measure the force of a blow and allow a recipient to experience what these levels of force feels like qualitatively. We may be able to do this with a high-speed camera or, alternatively, we could devise a tool that delivers a known amount of force over a cross-section that is similar to our rapier blunts.
Another possible use for this data is in the evaluation of other types of weapons. Llwyd has collected data from two-handed swords and rapier spears delivering a variety of different kinds of blows and it is possible that we could use this data to determine whether these different weapons strike significantly harder than single-handed rapiers. I intend to do this comparison in the near future as part of a separate discussion.
What about cuts? Sadly, Llwyd’s machine has not (yet?) been used to measure the force of cutting blows. My personal experience with cuts, having now fought C&T in two SCA kingdoms and having some limited experience fighting with HEMA groups outside the SCA is that in general, cuts are delivered with a level of force that is similar to thrusts and that the hardest cuts I have received (ruling out situations where I was actually punched using the guard) are at the very least similar in their level of force to the thrusts that i have received. The society rules for C&T require that blows be delivered with sufficient control so as not to injure opponents and so we might reasonably assume that blow forces will fall within a similar range to thrusts or, at the very least, that cuts will not typically land harder than the hardest thrusts. We could even provide some extra wiggle room and assume that cuts land in a range that is more typical of thrusts by two-handed swords (mean = 26.6 lbs, sd = 9.6, max = 55lbs). In any case, we should not expect that the range of blow forces delivered by controlled cuts should exceed the minimum level of force required to cause a concussion (~100 lbs).
The forces measured from thrusts performed using single-handed rapiers are much lower than the threshold we have established for causing a concussion. While no measurements were taken regarding cuts, it is unlikely that cuts typically land five times harder than thrusts, and so we should not expect that either cuts or thrusts will, during typical use, cause concussions on their own. However, the force of the blow may still be a contributing factor in causing concussions, but we must also look towards other factors in order to understand why concussions happen in SCA fencing. These findings should also be considered with the caveat that the human body is certainly capable of delivering the 100 lbs of force necessary and that it remains a possibility that a fighter acting through either gross negligence or through malice can deliver a cut or thrust with sufficient force to cause a concussion.
Until somewhat recently, concussions were seen as a relatively mild injury. However, in the last few years, a growing body of evidence has demonstrated the long-term consequences of these injuries to medical professionals and the public at large. Simply put, a concussion is a form of traumatic brain injury (TBI) caused by impact with the head [1,2,3, 4]. In the short term, symptoms can include disorientation, headache, memory loss, loss of consciousness, an inability to focus, tiredness, lack of coordination, nausea, and dizziness [1,2]. However, high-profile incidents involving former professional athletes combined with a substantial number of veterans returning from Operation Enduring Freedom and/or Operation Iraqi Freedom who have received head injuries has shown that concussions can result in serious long-term consequences including loss of cognitive abilities, depression, aggression, a loss of impulse control, anxiety, post-traumatic stress disorder, and premature death [1,3].
Symptoms of Concussions: Concussion Symptoms [Online image]. Retrieved May 5, 2016 from http://www.advancedvisiontherapycenter.com/services/sports_vision/concussion_management/.
What activities cause concussions?
Concussions can occur as a result of many different types of activities. For veterans of recent military operations in Iraq and Afghanistan, concussions typically occurred due to explosive devices, gunshot wounds (with and without helmet penetration), and vehicle accidents. Vehicle accidents are also a common cause of concussions  for people living their day-to-day lives along with falling and physical assault . Various sports such as football, soccer, hockey, etc can also lead to concussions. In these cases, concussions typically result from impacts with other players or from impacts with the ground [2,3,4]. SCA fencing shares these risk factors for concussions, particularly when we consider participation in melees. Fighters are also at risk for receiving concussions due to sword blows, which is the type of concussions that we will primarily focus on here.
Regardless of the activities that caused the impact, concussions typically occur in one of three ways:
Direct Impact with the Brain: This type of injury involves either the penetration of the skull by a foreign object or an injury that crushes the skull.
Yes, this would also cause a concussion:direct impact with the brain Spear in Brain [Online Image]. Retrieved May 5, 2016 from http://brainandspine.titololawoffice.com/2012/07/articles/traumatic-brain-injury-tbi/phineas-gage-and-yasser-lopez-offer-modern-brain-injury-research-more-data/.
Linear Acceleration of the head: Acceleration of the head through space can cause the brain to impact the inside of the skull.
Linear acceleration causes the brain to impact the inside of the skull: Andrews, M. (2012). Concussion Anatomy [Online image]. Retrieved May 5, 2016 from https://commons.wikimedia.org/wiki/File:Concussion_Anatomy.png.
Rotational Acceleration of the head: Rotation of the head on its axis can create shearing forces inside the brain that cut through neurons causing something called “diffuse axonal damage.” Indeed, rotational injury seems to be most responsible for sports injuries .
Concussion due to rotational acceleration leads to shearing of neurons in the brain. Graves, T. (2014). Concussion [Online image]. Retrieved May 5, 2016 from http://weillcornellbrainandspine.org/condition/concussion.
Given that our blunted weapons should, in no way result in penetration of the skull, we can limit our discussion to concussions caused by either linear or rotational acceleration. The obvious next question is: How much acceleration is necessary to cause a concussion? Unfortunately determining a clear threshold for injury is tricky. A recent study has shown concussions occurring from football impacts ranging from 60G – 168G (1G = acceleration due to gravity = 9.8 m/s2) . However it is also clear that it is possible to undergo far greater acceleration without sustaining a concussion. For our purposes, it is sufficient for us to use a value on the lower end of this range in order to determine where concussions will start to occur, which gives us a value ~ 60G. However, there is some evidence that lower levels of impact (30G) may be sufficient to cause significant brain damage , so keep in mind that this threshold is currently a contentious aspect of concussion literature and is subject to changing due to new research.
How much force is required to accelerate the head 60 Gs?
In other words, if we want to calculate how much force is needed to cause an object to accelerate a given amount, we will need to know its mass. A human head has a mass of approximately 5 kg and a fencing mask has a mass of approximately 2 kg, so for this calculation, let us assume a mass of 7 kg. First let us convert Gs of acceleration to the more typical metric unit, meters(m)/second(s)²:
A = 60G * 9.8m/s²/G = 588 m/s²
Then in order to calculate the necessary force to cause 588m/s² of linear acceleration, we get:
F = 7kg * 588 m/s² = 4116 kg*m/s²
In the metric system, the unit for force is the Newton (N), which is equal to 1 kg*m/s², so the necessary force to cause this level of linear acceleration is 4116 N. However, I expect that most people reading this series of articles are located in the US and so Newtons aren’t a particularly intuitive unit of measurement. Fortunately the unit for force in the US/Imperial system of measurements is the pound and the conversion factor between these measurements is 4.45 N = 1 lb. We then have:
4116 N = 925 lbs
Calculating the necessary force required to cause this level of rotational acceleration is slightly more complicated. Rotational force is calculated using a slightly different equation, so rather than using F = M * A, we instead calculate for torque:
torque(τ) =moment of inertia( I) * angular acceleration(α)
Since we have already converted from Gs to m/s2, we must now calculate the moment of Inertia. The equation for this is as follows:
I = constant (k) * mass (m) * radius (r)²
Location of the atlas (shown in red) and axis (immediately below and encapsulated by the atlas). These bones form the joints that allow the head to rotate. Anatomography. (2012). Atlas [Online image]. Retrieved May 5, 2016 from https://commons.wikimedia.org/wiki/File:C1_lateral.png.
So now, in addition to knowing the mass of the head, we must also know its radius. Anatomically the head rotates vertically (nodding) in the joint between the occipital bone of the skull and the atlas bone and horizontally (side-to-side) in the joint between the atlas bone and the axis bone (the atlas is shown in red above and the axis is mostly obstructed by the atlas, but is visible as a small sliver of white under the atlas). Knowing this, we can measure from this point to the chin of a fencing mask, which is around 25cm. We can therefore calculate I as follows:
I = k * 7kg * 0.25 m² = k * 7 * 0.0625 m = k * 0.4375
You will note that this leaves the term, k which I have not yet defined. In this equation, k is a constant term that is dependent on the shape of the object being rotated. Choosing an appropriate k-value is complicated, so let us come back to it. For now, let k = 1. We can then finish calculating the necessary force to cause this kind of rotational acceleration:
τ = 0.4375 kgm²*588m/s²= 257.25 N*m
In this case, the “meters” part of the result is related to the radius, so we can get rid of it as follows:
257.25 N*m / 0.25 m (the radius) = 1029 N = 231.24 lbs
Choosing a value for k
Calculating a precise value for k is tricky because the head, particularly a head encased in a fencing mask is strangely shaped, the axis of rotation is off-center, and the mass is not uniformly distributed, however we can estimate a value for k by selecting a geometric shape that is similar to the shape of the head and using its k value here. That is, As the old physics joke goes, assume a spherical head. In this case, the value for k is 0.4. So, taking that into consideration, we would then multiply our result by this value:
1029 N * 0.4 = 411.6 N = 92.5 lbs
Given that we’re “fudging” the shape of the head here, we should take this value with a grain of salt and understand that the correct value should lie somewhere between these two values. In other words, the needed force is somewhere between 412N – 1029 N or in Imperial measure, 93 lbs – 231 lbs.
From the perspective of our combat sport, rotational acceleration poses the greatest risk for concussions, which is consistent with research into concussions in other sports. Importantly, the level of force needed to cause a concussion due to rotation is relatively low. In the next article, we will compare these levels to the measurements of striking force carried out by Baron Llwyd.
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