VERTICAL JUMPING IN GALAGO-SENEGALENSIS - THE QUEST FOR AN OBLIGATE MECHANICAL POWER-AMPLIFIER

Bushbabies (Galago senegalensis) are renowned for their phenomenal jum ping capacity. It was postulated that mechanical power amplification m ust be involved. Dynamic analysis of the vertical jumps performed by t wo bushbabies confirms the need for a power amplifier. Inverse dynamic s coupled to a geometric musculo-skeletal model were used to elucidate the precise nature of the mechanism powering maximal vertical jumps. Most of the power required for jumping is delivered by the vastus musc le-tendon systems (knee extensor). Comparison with the external joint- powers revealed, however, an important power. transport from this exte nsor (about 65%) to the ankle and the midfoot via the bi-articular cal f muscles. Peak power output likely implies elastic recoil of the comp lex aponeurotic system of the vastus muscle. Patterns of changes in le ngth and tension of the muscle-tendon complex during different phases of the jump were found which provide strong evidence for substantial p ower amplification (x15). It is argued here that the multiple internal connective tissue sheets and attachment structures of the well-develo ped bundles of the vastus muscle become increasingly stretched during preparatory crouching and throughout the extension phase, except for t he last 13 ms of the push-off (i.e. when power requirements peak). The n, tension in the knee extensors abruptly falls from its maximum, allo wing the necessary fast recoil of the tensed tendon structures to occu r.