Long Toes May Give Sprinters More Speed

Expert Discussion Biomechanics and Physiology
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Long toes may give sprinters more speed

Here’s an excerpt: Research on sprinters suggests that runners with long toes and short heel bones could have an advantage over other athletes.

Sabrina Lee, a biomechanics researcher at Simon Fraser University, and Stephen Piazza of Penn State University compared ultrasound images of 12 college sprinters and 12 non-athletes.

They used these images to compare the subjects’ toe lengths and examined how the Achilles tendon at the back of the heel slides during ankle motion.

The researchers found that the distance between the Achilles tendon and the centre of the ankle joint was shorter in the sprinters.

Cont’d…

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SHORT HEELS GIVE ELITE SPRINTERS THE EDGE

Kathryn Knight

kathryn@biologists.com

Figure 1

When 100 m sprinters launches themselves from the starting blocks, the race can be won or lost in the first few strides. Acceleration through the first few strides is the key to winning gold. So when Stephen Piazza was approached by an American football star, who sprints in his position of wide receiver, to find out how he could improve his technique and training regime, Piazza decided to focus on the athlete’s ankles to try to discover what gives elite sprinters the edge over ordinary mortals (p. 3700).

The effectiveness of an accelerating sprinter’s push off depends on the amount of leverage that the calf muscles have when pulling on the back of the heel to pull it up as it pushes the toes down, and off the ground. Piazza figured that the athlete’s foot would have a large distance from the ankle to the back of the heel to produce a long heel lever' for the calf muscle to pull on when pushing the toes down. In this case, the calf muscle would have to contract and pull the heel up over a long distance, so Piazza measured how far the athlete's tendon moved (translated) while pulling the athlete's heel up to see how it compared with that of non-sprinters. Piazza says I thought it would be one of the largest (tendon translations]) we had ever measured’. But when he and his student, Sabrina Lee, measured the distance, they were surprised to find that it was much shorter than average. Was the football star the exception or the rule?

Piazza decided to compare the Achilles’ tendon translation of elite athletes with that of non-sprinters. Working with sprinters and long jumpers from Lock Haven University, and local non-sprinters, Piazza and Lee used ultrasound imaging to measure the tendon’s translation as the subjects pointed their toes. Amazingly, the distance was 25% shorter in the elite athletes than in the non-sprinters. Instead of benefiting from the mechanical advantage of having a long heel lever, the sprinters seemed to be at a mechanical disadvantage because their heel levers were much shorter.

Puzzled by this unexpected discovery, Piazza turned to the literature to find out how animal sprinters’ ankles are constructed, and quickly realised that the human elite athletes were built inline with their animal counterparts, which also have short heel levers. So how does this mechanically disadvantageous arrangement give elite sprinters the edge over weekend joggers?

Piazza and Lee realised that a fundamental property of all muscles could be responsible for the sprinters’ unexpectedly short Achilles’ tendon translations. He explains that muscles that contract quickly cannot generate much force, giving runners with a long moment arm a weak push off despite their increased mechanical advantage. However, muscles that contract slowly produce much greater forces that overcome the mechanical disadvantage of a short heel lever, giving sprinters with a short heel lever a powerful push off.

Testing his theory with a mathematical model of a sprinter’s body, it was clear that the extra force generated by the calf muscle as it pulled the short heel lever would provide sprinters with the additional acceleration required to get ahead in the first few strides. And when the duo compared other physical characteristics between the sprinters and non-athletes, they noticed that the sprinters’ toes were almost 1 cm longer than those of the non-sprinters. Not only could the sprinter generate more force while accelerating, but their longer toes allowed them to remain in contact with the ground longer during each stride, giving them longer to push against the surface and out perform slower sprinters.

References

Lee, S. S. M. and Piazza, S. J. (2009). Built for speed: musculoskeletal structure and sprinting ability. J. Exp. Biol. 212,3700 -3707.[Abstract/Free Full Text]

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What do others think about this statement? I personally don’t think it’s true at all. There are a lot of lower level sprinters (and even some non-sprinters) whose first few steps are very fast. In my opinion, top speed is by far the most important factor determining the outcome of a race. I thus think that any biomechanical abnormalities found in sprinters should first and foremost be interpreted within the context of maxV.

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One of the researchers is at my university, and I have never met this person or even heard of her research until now. Gives you an idea of how much practical research she did for this project.

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Isn’t the basis of the theory that’s written about in the Kathryn Knight paper that you need to have foot structure which promotes longer ground contact times? Wouldn’t that make you run slower?

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No.2

I am sure these people would say something along these lines;

  1. It’s very early days for the findings reported in the paper. Even if the shapes of athletes’ feet determine their sprinting capability, they are a long way from being able to predict anything on the basis of foot geometry.

  2. There are many, many factors that determine sprinting performance besides foot and ankle mechanics, and it is not clear what the importance of foot mechanics is relative to those other factors.

As scientists, I am sure they will conduct further research over the years to come. However, it is surely a move forward in one way or another. I personally would always encourage people to conduct all sorts of testing but would judge each research on its own merit. These findings, I am sure, could be interpreted by some as very accurate, while others would be dismissive. It is all relative and depends on an individual, as we are all different.