Rm. Alexander, LEG DESIGN AND JUMPING TECHNIQUE FOR HUMANS, OTHER VERTEBRATES AND INSECTS, Philosophical transactions-Royal Society of London. Biological sciences, 347(1321), 1995, pp. 235-248
Humans, bushbabies, frogs, locusts, fleas and other animals jump by ra
pidly extending a pair of legs. Mathematical models are used to invest
igate the effect muscle properties, leg design and jumping technique h
ave on jump height. Jump height increases with increased isometric for
ce exerted by leg muscles, their maximum shortening speeds and their s
eries compliances. When ground forces are small multiples of body mass
(as for humans), countermovement and catapult jumps are about equally
high, and both are much better than squat jumps. Vertebrates have not
evolved catapult mechanisms and use countermovement jumps instead. Wh
en ground forces are large multiples of body mass, catapult jumps (as
used by locusts and fleas) are much higher than the other styles of ju
mp could be. Increasing leg mass reduces jump height, but the proximal
-to-distal distribution of leg mass has only a minor effect. Longer le
gs make higher jumps possible and additional leg segments, such as the
elongated tarsi of bushbabies and frogs, increase jump height even if
overall leg length remains unchanged. The effects of muscle moment ar
ms that change as the leg extends, and of legs designed to work over d
ifferent ranges of joint angle, are investigated.