LONG JUMPERS are full of contradictions. They brake on take-off and their
tendons, which normally store energy by stretching, contract. 鈥淭his turns around
our understanding of how tendons work,鈥� says Andre Seyfarth of the Institute for
Sports Science in Jena, Germany.
Seyfarth and his colleagues in Germany and the Netherlands found that tendons
in the leg shorten just before a jump. This allows the knee extensor muscles to
stretch to a peak, braking the athlete to allow them to take off at the optimal
angle (Journal of Experimental Biology, vol 203, p 741). 鈥淭he jumper
has only a quite short time to redirect the horizontal running movement to an
upward movement at take-off,鈥� says Seyfarth.