Gabe Mirkin, M.D.
Running seems like a safe sport, so many people are surprised to learn that it causes frequent injuries to
muscles, tendons, bones and joints. During running, your foot strikes the ground with a force equal to
three times body weight, a force more than double that of walking. To convince yourself, place your
hands on the huge quad muscles in the front of your upper leg while you run. Each time your leg strikes
the ground, you feel the muscle shake like jelly.
A study from the University of Wisconsin-La Crosse shows that as people start to feel tired during
running, they shorten their strides to decrease the force of their foot striking the ground. This lessens the
force of their heel striking the ground and places it forward to the area behind the big toe. To
compensate for the decreased force of their feet hitting the ground, they move their legs at a faster
cadence. You should use this information to prevent injuries when you run. You can help to protect
yourself from injury by shortening your stride, which shifts your foot s force forward. You can keep
your speed by moving your legs at a faster cadence.
Wilson JD and Kernozek TW. Plantar loading and cadence alterantions with fatigue. Medicine and Science in Sports and