Which muscle is the key to your running stride? Your first instinct is probably to think of big power generators like the quadriceps and hamstrings. But according to researchers from the University of Jyväskylä, in Finland, the underappreciated heroes of your gait are the ankles. They used 3d gait analysis to measure the force produced by different muscle groups while running at various speeds, and then compared those forces to the maximum forces each muscle was capable of producing.
The results, published in Medicine & Science in Sports & Exercise, showed that both the quadriceps (front of upper leg) and ankle extensors ( back of lower leg) produced forces equivalent to eight or nine times body weight during running and sprinting. But while the quadriceps were capable of a maximum force of nearly 14 body weights, the ankles were already near their max of about 10. That means your ankles are constantly working at a higher percentage of maximum than other leg muscle groups.
The same researchers previously showed that one of the biggest differences between older and younger runners is in ankle strength, suggesting that loss of ankle muscle is an important contributor to age-related slowing. Does this mean that ankle-strengthening exercises like calf raises might help ward off the ravages of time? It’s an interesting hypothesis, but it still needs to be tested.