Force depression following muscle shortening has been studied extensively using artificial electrical stimulation, but has not been studied at all during voluntary contractions. There is the possibility that force depression properties may differ conceptuaIly between muscle stimulated artificially and muscle contracted voluntarily. Therefore. the purpose of this thesis was to investigate force depression following muscle shortening and its properties related to speed and distance of shortening for human voluntary contraction.

The isometric force produced immediately following muscle shortening was depressed compared to the corresponding force during purely isometric contractions for voluntary contractions and was typically accompanied by constant muscle activation. Therefore, it was concluded that force depression is an actual property of skeletal muscle rather than an artefact of electrical stimulation. However, the amount of force depression was independent of the speed and distance of shortening;​ a result that was in direct contrast to the findings reported on artificially stimulated muscle.