Supraspinal Responses and Spinal Reflexes

When vibration, induced by harmonic mechanical oscillations, is applied to the entire human body or individual segments and structures, various short- and long-term neural changes occur. This chapter presents an overview of vibration stimulus effects on the central nervous system. First, we address the modulatory impact of vibration on supraspinal level, e.g. on the excitability of the sensorimotor networks as well as on the intra- and inter-hemispheric cortical processes. Effects on neural conduction, motoneuron activation thresholds, facilitation and inhibition are highlighted. Second, we review the inhibitory and facilitatory effects of vibration on spinal level, e.g. on alpha-motoneuron pool excitability as well as on pre- and post-synaptic neural transmission. Combined, the findings from experiments in humans using focal or whole-body vibration suggest that vibration amplifies the acute and chronic neuromuscular responses achieved during low intensity exercise, such as enhanced strength and power, improved mobility and flexibility, balance and postural control. These effects can be used strategically during training and therapy and are particularly beneficial for the elderly and patients suffering from neuronal disorders.