Introduction to Sports Biomechanics: Analysing Human Movement ...

The standing vertical jump
MOVEMENT PATTERNS – THE ESSENCE OF SPORTS BIOMECHANICS
Figure 1.22 Standing countermovement vertical jump with ‘model’ arm action. Top left: starting position; top right: lowest
point; middle left: take-off; middle right: peak of jump.
The standing vertical jump looks simple. The extensor muscles of the hips and knees
and the plantar flexors of the ankle contract eccentrically to allow the knees and hips to
flex and the ankles to dorsiflex simultaneously in the preparation phase. The action
phase involves the simultaneous extension of the hips and knees and plantar flexion of
the ankles through shortening (concentric) contraction of the muscles that extend or
plantar flex these joints and drive the body vertically upwards. This sequence is evident
in Figures 1.20 to 1.23. The main difference between the countermovement jump
with no arm action in Figure 1.20 and that with a free arm action in Figure 1.21 is that
the arm actions in the latter jump, if properly coordinated with those of the legs,
will enhance performance of the jump. You should compare Figure 1.21, in which the
jumper used his normal arm action, with the simpler arm action in Figure 1.22, based
on a simple biomechanical ‘model’, and the uncoordinated arm action in Figure 1.23.
The jumper performs as well with the model action as with his normal action, part
of which is nearly identical to the model. However, the arm action of Figure 1.23,
which is roughly the reverse of the model action, causes a marked decline in jump
performance. In the model and normal jumps, the arm and leg movements are well
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