Neural adaptation to resistance training: changes in evoked V-wave and H-reflex responses

1 Department of Neurophysiology, Institute of Medical Physiology and 2 Anatomy Department C, Panum Institute, University of Copenhagen; 3 Copenhagen Muscle Research Centre, Rigshospitalet; 4 Team Danmark Test Centre, Sports Medicine Research Unit, Bispebjerg Hospital, DK-2200 Copenhagen, Denmark Combined V-wave and Hoffmann (H) reflex measurements were performed during maximal muscle contraction to examine the neural adaptation mechanisms induced by resistance training. The H-reflex can be used to assess the excitability of spinal -motoneurons, while also reflecting transmission efficiency (i.e., presynaptic inhibition) in Ia afferent synapses. Furthermore, the V-wave reflects the overall magnitude of efferent motor output from the -motoneuron pool because of activation from descending central pathways. Fourteen male subjects participated in 14 wk of resistance training that involved heavy weight-lifting exercises for the muscles of the leg. Evoked V-wave, H-reflex, and maximal M-wave (M max ) responses were recorded before and after training in the soleus muscle during maximal isometric ramp contractions. Maximal isometric, concentric, and eccentric muscle strength was measured by use of isokinetic dynamometry. V-wave amplitude increased ~50% with training ( P