Increase in Neuromuscular Activity and Oxygen Uptake during Heavy Exercise.

Abstract

In order to examine the contribution of neuromuscular activity to the slow increase in VO2 during heavy exercise, integrated electromyogram (iEMG) of dominant working muscle and VO2 was compared in seven subjects during constant-load cycling exercise at the intensity of 10% below and 30% above ventilatory threshold (VT) for seven minutes. VO2 and iEMG after 4th min in above VT test was significantly correlated (r = 0.53, p less than 0.01) and VO2/iEMG was constant after 4th min, indicating coupling of iEMG with VO2. The results suggested that the slow increase in VO2 during heavy exercise may result from the changes in the recruitment pattern of motor units.