Task specific corticospinal adaptations following ballistic strength training

Abstract

Strength training plays an important role for motor performance in sports and in neurological rehabilitation. The outcomes of rehabilitative interventions as well as the success of physical training programs largely rely on adaptations of the central nervous system. Nevertheless, the sites of neural adaptation and thus the mechanisms of training are still largely unknown. Recent research has focussed on neural correlates like H-reflexes or magnetic evoked potentials to describe neural adaptations following training (Voigt et al. 1998; Aagaard et al. 2002; Carroll et al. 2002; Perez et al. 2004; Jensen et al. 2005). Most of these studies applied isometric voluntary contractions to imitate the functional state. This could be critical because Nielsen and co-workers were able to show that different sub-systems of corticospinal activation were involved during dynamic versus tonic contractions of shank muscles (Nielsen et al. 1993; Nielsen and Petersen 1995). Their studies indicated that fast conducting orticospinal fibres with monosynaptic projections onto spinal motoneurones are involved in the initiation of voluntary leg movements while tonic activation involved other, presumably indirect pathways. Therefore, we hypothesised that corticospinal adaptations are specific for the motor-task.