NEUROMUSCULAR ELECTRICAL STIMULATION AND LOCAL VIBRATION: CONTRIBUTION OF REFLEX ACTIVATION OF MOTOR UNITS TO NEUROMUSCULAR ADAPTATIONS

Neuromuscular electrical stimulation (NMES) is commonly used to generate muscular contractions.  NMES can be used for training/rehabilitation purposes as it has the potential to improve neuromuscular function in healthy individuals as well as in different patient populations. Conventional NMES generates contractions predominantly by activating the motor axons beneath the stimulating electrodes (i.e. via peripheral pathway).

Nevertheless, an excessive discomfort and a premature fatigue are the main drawbacks for the clinical application of NMES. Wide-pulse (≥ 1 ms) NMES has recently been proposed as an alternative to its conventional form because it favours a physiological recruitment of motor units (i.e. via central pathways). This is mainly due to the fact that wide pulses activate sensory axons (e.g. afferent Ia from neuromuscular spindles). Interestingly, local vibration is known to facilitate reflex recruitment of motor units through activation of muscle spindle afferents. 

Thus, the main objective of this thesis is to evaluate and compare the adaptations of neuromuscular function induced by different forms of NMES (conventional vs. wide-pulse) with and without the superimposition of local vibration of the stimulated muscles. Two muscle groups (i.e. knee extensors and plantar flexors) will be studied. The results should help to define basic recommendations for the clinical use of the combination of NMES and vibration therapies.