Fastest Man Alive Isn't a Specimen of Perfect Symmetry?

POSTED ON IN Healthy Lifestyles BY Christopher Centeno

leg asymmetry What if the fastest man alive was an asymmetrical mess due to scoliosis? While symmetrical people are perceived by our brains as the most physically beautiful, what if symmetry wasn't the best formula for sport-specific, physical performance? That would change a lot of perceptions and some biomechanical science as well. When we talk about symmetry, or balance, in the human body, this means left-right symmetry (which is the left and right side in balance) and front-back symmetry (which is the front and back in balance). The prevailing thought is that we are built to function and feel best only when there is full body symmetry. While it seems logical that asymmetry would also negatively affect just about any level of physical performance, an incidental finding during one study suggests that leg asymmetry, which means having one leg longer, or significantly stronger, may not negatively impact running speed.

Problems Due to Lack of Body Symmetry

As I've mentioned before, the body is one big connected machine, and lack of body symmetry in one area is sure to create a domino effect throughout the rest of the body. When one joint loses normal motion, other parts will certainly be impacted. For example, when one shoulder is held higher, due to stress or an injury for example, or when one leg is shorter, certain parts will wear out faster.

Usain Bolt: Leg Asymmetry May Not Affect Running Speed

The new study (found on page 1072 of the pdf link) presented at the 35th International Conference on Biomechanics in Sport last month used motion data captured from video of a professional track and field event. Four runners, including Usain Bolt, the world's fastest runner, were included in the study, and two measurement approaches were used. One approach, termed the “two-mass model,” divides the body into lower-limb mass and the remaining body mass. Contact (the foot striking the ground) and aerial (the foot in the air, or when the foot was not striking the ground) time measurements were taken as well as ankle velocity during contact and lower-limb vertical acceleration. The purpose of the study was to determine the most effective motion-based method (the two-mass model was the conclusion) to estimate ground reaction forces, in this case from the video of the track and field event itself (as opposed to a controlled environment, such as a treadmill study). However, researchers discovered something interesting in the process: Usain Bolt's legs may be asymmetrical as the timing and force measurements differed between each leg. This presented the question, if Bolt's legs perform differently when he runs, is it possible leg asymmetry doesn't affect running speed? However, it could also present the question, if Bolt's legs were symmetrical, is it possible he would run even faster? So, certainly, more-controlled studies will need to be done. The upshot? These video observations will have to be confirmed by further study. However, given that Usain Bolt has reported having scoliosis ever since he was a teenager, it's more likely than not that he does have an asymmetrical gait, just like other scoliosis patients. Hence, does that asymmetry give him an edge? Could he be even faster if he was symmetrical? If it's the former, this will upend a long-standing belief that our athletes should be like our fashion models, beautifully symmetrical. In fact, it may even spark new training routines to create body asymmetry that can enhance performance.  

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