Voluntary Activation During Isokinetic Contractions in Subjects with Neuromotor Disorders

Activation is the amount of voluntary recruitment of a muscle during voluntary contraction. Full activation implies the recruitment of all muscle fibres at their tetanic frequency. In healthy subjects, and even in sports performances, full activation may be rarely achieved despite a subjectively maximal effort. Highly decreased activation has been observed in patients affected by various orthopaedic and neurological disorders. In these subjects, paresis may be caused or aggravated by primitive impairments of the central nervous system and/or, by stimuli arising from peripheral damaged tissues that inhibit the corticospinal or the intraspinal recruitment of motoneurones ("arthrogenous muscle weakness"). There are numerous investigations in the literature on activation measured during isometric contractions, while they are substantially missing as far as isokinetic concentric contractions