The hardest-working muscles in running are the calves, researchers say.
Runners talk a lot about their quads and hamstrings – big muscles that generate big forces, and also tend to get injured a lot. The muscles of the ankle get less respect. But according to a group of researchers in Finland, that’s a mistake.
The researchers, from the University of Jyväskylä, just published their latest paper in Medicine & Science in Sports & Exercise. In it, they compare the force produced by ankle extensor muscles (the calves) to the force produced by knee extensors (the quadriceps) during walking and running, and conclude that the ankles are working a lot harder as a proportion of their maximum force.
To get an apples-to-apples comparison of forces during running and “maximum” forces, the researchers used a 3D motion-capture system to analyze the movement of the legs and calculate the forces involved. The maximum force was assessed by having the subjects hop up and down as high as possible for 10 seconds, which is apparently the best way to produce the highest possible forces.
Without further ado, here’s what those forces looked like for the knee extensors and ankle extensors:
The key thing to notice is that the knee extensors can generate almost 14 bodyweights worth of force while hopping, but only need eight or so while running and nine while sprinting.
For the ankle extensors, the peak hopping force of just under 10 bodyweights is barely higher than what’s required for sprinting, and a bit higher than the eight needed for running. The conclusion is that ankle muscles are working far harder during running than knee extensors.
What does this mean in practical terms? An earlier study from the same group (which I wrote about here) looked at three groups of runners with average ages of 26, 61 and 78, and found that the biggest muscular difference between the three groups while running was in the power produced by the ankle muscles. Since ankle muscles are relatively small compared to upper-leg muscles, the researchers suggested, they’re the first to be affected by age-related muscle loss.
A study from East Carolina University and Wake Forest University produced similar results last year.
Does this mean that strengthening your calf muscles, for example by doing exercises like calf raises, will enhance your running performance and stave off the effects of aging? That remains purely speculative at this point. The results are certainly intriguing – so hopefully some enterprising researcher will test this theory.
