Gil Pezza, La Frase Schermistica, Ospiti

On the biomechanics of posterior leg knee injuries in saber fencing

infortunio ginocchio posteriore
The first article I’m proposing you to open our new site is written by Gil Pezza, fencing master, former fencer of Italian National Team and attorney in USA.
G.Toran
Enjoy!

GIL PEZZA – February 2019

My educated guess is that knee and ankle injuries are the most common injuries in fencing practice and competition; but I could be very wrong. In fact, according to some of my colleagues who coach saber the most common injuries are to the hamstring muscles and, for older fencers, to the Achilles tendon. One can only guess because there do not seem to be comprehensive exercise-related morbidity studies pertaining to fencing, with a detailed breakdown of the relevant data and the mechanics of the injury.

Be that as it may, by viewing reports in the media there seems to be a significant incidence of posterior knee injuries in men and women saber fencing even though many of the injured are elite saber fencers who follow a very professional training regimen.i Clearly, this means that further research is needed to reduce the risk of this type of injury.

infortunio ginocchio posteriore
Aug 7, 2016 – Source: Patrick Smith/ Getty Images South America

This is not a research paper; far from being it. These are mere observations on the dynamics of fencing injuries to the joints of the posterior leg to determine the best angle for the posterior foot to assume on landing while the fencer is retreating with sudden acceleration. Most importantly, its conclusions, are just preliminary in nature and are drawn from common sense observations and not from hard data.  Hopefully, it may inspire the systematic collection of data on fencing injuries and further research on this topic.ii

Notwithstanding congenital conditions (in which a knee is never in a normal condition), certain sports or certain activities or movements of the body and legs may cause the knees to be under stress in valgus or in varum positions. Furthermore, for the purposes of this discussion, we will postulate that the musculoskeletal apparatus of human beings is made for running at maximum acceleration forward and not backwards; and when the knees are not in a normal position and are under stress either in valgus or in varum, they are more susceptible to injury.  It should be noted that any component of the musculoskeletal structure can be injured if the right mix of physical forces come into play regardless of whether they are in a normal or abnormal position.  For example, the ground reaction force on the ankle can travel upwards and injure the Achilles tendon or the knee joint. Whether you move forward or backward the forces at play remain the same and they apply to all weapons. There is the force caused by friction, there is the force that causes acceleration (of the/the fencer who moves forward or backward) and there is, of course, the force of gravity.

But let’s first look at the bio-mechanics of the on-guard position in fencing.  In the traditional fencing guard, the feet are at a 90-degree angle in relation to each other with the front foot pointed forward towards the opponent.  If we then consider that the most effective position for a human body to accelerate forward is to have the feet parallel to each other with the shoulders square to them, then the fencing guard is, from a dynamic’s perspective, very inefficient.  Furthermore, in classical fencing efficient dynamics were even more challenged because the axis of the shoulders was almost parallel to the line of direction of the feet.  As fencing became more and more athletic from the 1960s onwards two things happened. First, the axis of the shoulders rotated in the on-guard position (clockwise for the right-handed fencer and counterclockwise for the left-handed fencer) to intersect the line of direction of the feet at least at a 45-degree angle, to favor the fast movement forward. Secondly, the back foot followed the rotation forward of the back shoulder to be at approximately a 45-degree angle with the front foot. As a result, the fencers soon started cross-stepping until the cross steps morphed during the mid-1970s into a full-fledged running attack in foil and saber. For this reason, defense became the tactics of last resort. In fact, the top foil and saber fencers in the world were those with the strongest offense and counter-offense capabilities.  Of course, all fencers run, including epee fencers, when time is running out during a bout; except for saber fencers who cannot cross step forward since 2004. This rule change for saber fencing, however, did not diminish the forward acceleration of saber fencers who now hop, jump and flunge like circus acrobats. With respect to retreating, fencers are limited to the following options: Standard retreats in the on-guard position; running backwards with very short cross-steps and with the feet parallel to each other; and longer cross-steps backwards while landing with the posterior foot at 90 degrees or less with the front foot.


It is important first to draw the distinction between cross stepping backwards in fencing versus just running backwards, proper. Yes, they are both cross steps but the mechanics of each one is different from the other. The most significant distinction between running forward and running backwards lies in the fact that when you run backward the upper body moves first; when you run forward the lower body, instead, goes first.  In fact, when you run backwards the steps are shorter and tucked-in and, more importantly, you are always setting your own pace. But if someone were chasing you, you would have to turn around and run because (a) you would not be able to outrun who is chasing you (not an option in fencing) and (b) if you attempted to accelerate too fast with short backwards steps with the feet parallel to each other you will fall as soon as the vertical axis from your center of gravity falls beyond the midpoint of your feet. In fencing, the latter of these situation happens when the retreating fencer is simply trying to get out of the attacking fencer’s reach as quickly as possible and, indeed, we have all seen quite a few saber fencers fall backwards this way. Let’s continue to examine the bio-mechanics of the cross step back.

Cross Step Backwards

A. Higher risk of injury to knee

The initial cross step backwards is executed with the front leg which lands with the corresponding foot still pointed forward. The second part of the cross step is preceded by a 90-degree counterclockwise outward rotation (for the right-handed fencer) of the hip joint of the posterior leg, which causes the knee joint to be pushed out in varum and to land the foot at a 90-degree angle with the front foot. Therefore, putting the fencer’s momentum (mass x velocity) backwards and weight (mass x g) on the landing of the second foot. Unless, the foot rolls at the ankle upon landing (with injury to the ankle joint) and with  the posterior knee flexing outwards, in varum, the fencer’s resultant force will transfer from the ankle joint to the knee joint and, voilà, the potential of injury at the knee joint. It should be noted, however, that even if one fences with the back foot at a 45-degree angle or less, if the cross step with the posterior leg is executed with an outward rotation of the hip joint, the posterior foot will most likely land at a 90-degree angle; unless the same hip joint is quickly rotated in the opposite direction just before landing the foot.

B. Lower risk of knee injury but higher risk of injury to Achilles tendon

In this variation of cross step, the fencer takes a second cross step and lands on his forefoot keeping it either at a 45-degree angle or in parallel with the other; this being done without the outward rotation of the hip joint. In this case, the fencer’s weight will remain be on the back leg, but the foot will still be able to flex and act, in effect as a shock absorber with respect to the fencer’s resultant force. The downside to this is that shock will be absorbed by the Achilles tendon.

C. Lower risk of injury to the posterior knee and Achilles tendon

As in section B, above, but, as the fencer pushes off the forefoot of the anterior leg during the first cross step, he transfers the weight of the upper body on the anterior by leaning forward with  the upper body, in effect, executing a reverse half-lunge; while landing on the bowl of the back foot (kept either in parallel or at a 45 degree angle with the front foot) but with the weight of the fencer primarily on the front leg thereby reducing stress on the back leg and on the Achilles tendon.

Final thoughts and recommendations.

1. There is no perfect solution to avoiding joint injuries to the legs in fencing. In fact, by modifying the biomechanics of the movements of retreat, the resulting force just transfers to the weakest spot elsewhere on the skeletal muscle structure. The choice perhaps consists in choosing those movements that keep the joints in a normal position and distributing the fencer’s resulting force on two support points. In other words, opting, potentially for a minor injury instead of a much more serious one.

2. From the point of view of the laws of physics, I hypothesize that:

– the most serious injuries to the knee are probably caused by the cross-step backward coupled with a rotation of the hip joint outward with a hard landing of the posterior foot at a 90-degree angle; rather than with the normal retreats where the weight is more evenly distributed on the two legs.

– the most dangerous situation for a fencer may occur after a sudden change of direction backwards after the opponent has suddenly “stolen” the distance.

– for veterans fencers the risk presented in maintaining a 90-degree guard may decrease with age, (60+) while keeping the back foot at approximately 45-degree angle may increase the likelihood of injury to the Achilles tendon.

3. It is imperative for fencers to take preventive measures like athletes engaged in sports that require powerful forefoot push offs. So, warming up, stretching the calf muscle and stretching the Achilles tendon are a must. Fencer should consider eccentric strengthening of the Achilles tendon, the gastrocnemius and the soleus muscles to further mitigate the risk of injury to the Achilles tendon.

4. Young fencers must learn how to run and fall backwards; as well as being ambidextrous with respect to footwork. Regardless, to avoid asymmetry-induced injuries, young fencers must be put on a specialized training program to balance the uneven musclegrowth in their developing bodies.

5. The wireless transmitter (WT) box should not be placed on the fencer’s waist in the back.  Landing on the WT box while falling backwards could injure the fencer’s back.

6. Training in crisis management on the strip should not only be approached from a tactical perspective, but it should also focus on the mechanics of the movements as they impact the joints of the fencer’s legs.

7. Fencers must learn active defense measures to slow down the opponent while retreating.

8. There is a need to determine the scope of the injuries in fencing by establishing its etiology, mechanism of injuries and the risk factors involved. To do so, it is necessary to establish a universal, FIE , definition of injury and develop a universal incident report.

9. The FIE should establish an online portal via which each National federation could upload incident reports. In turn each National federation would be able to enter incident reports from competitions and from clubs at practice.

10.The FIE should lead the charge in developing an application for mobile phones for collecting/uploading incident reports together with corresponding photographs and videos of incident, when available.

11. Sport physicals should also red-flag certain congenital conditions (e.g., flat feet, knee valgus and femoral anteversion) that can predispose the athlete to injuries to the leg joints so that therapeutic measures can be taken in parallel with participation in fencing.

12. The risk of injuries to the leg joints increases for young fencers who are significantly overweight or obese even if their acceleration could be significantly slower. The dramatic increase in obesity in children and adults now presents a problem in sport; especially during the period when they start the new activity and the time it takes them to get into shape. Too often, instead, I see overweight children and adults who are prescribed the same warm up and training regimen of fencers with normal BMI values. This means that the coach does not understand the laws of physics. Therefore, fencing coaches must know the mechanics of fencing movements and their impact on the anatomy of the athlete.

i Some studies suggest that women fencers are at greater risk of injury than men and that and saber fencers are at greater risk of injury that foil and epee fencers. Common Fencing Injuries, by Nader Abdelkader, B.Sc. D.C. FCCSS (candidate) https://fencingontario.ca/images/sitepicts/Documents/Fencing%20injuries.pdf

ii See, for example, Biomechanical analysis of knee joint mechanism of the national women’s epee fencing lunge movement. Fei Zhengwei1 and Zhao Chuanjie – School of Physical Education and Sport Training, Shanghai University of Sport, Shanghai PR China.

http://www.alliedacademies.org/articles/biomechanical-analysis-of-knee-joint-mechanism-of-the-national-womens-epee-fencing-lunge-movement-7064.html

 

 

(1) Comment

  1. Hello, Thank you for this article. It is quite interesting. I think you might have wanted to say 1994 instead of 2004 for the date of prohibiting the cross step forward in saber. With the ever increased speed of sabre today, could a possible solution for these kinds of injuries be to eliminate the strip and allow off line footwork as any done by practitioners of any other combat sport?

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