Effects of prior heavy exercise on VO2 kinetics during heavy exercise are related to changes in muscle activity

kinetics during heavy exercise are related to changes in muscle activity. J Appl Physiol 93: 167–174, 2002; 10.1152/ japplphysiol.01217.2001.—We hypothesized that the ele-vated primary O2 uptake (V̇O2) amplitude during the second of two bouts of heavy cycle exercise would be accompanied by an increase in the integrated electromyogram (iEMG) mea-sured from three leg muscles (gluteus maximus, vastus late-ralis, and vastus medialis). Eight healthy men performed two 6-min bouts of heavy leg cycling (at 70 % of the difference between the lactate threshold and peak V̇O2) separated by 12 min of recovery. The iEMG was measured throughout each exercise bout. The amplitude of the primary V̇O2 response was increased after prior heavy leg exercise (from mean SE 2.11 0.12 to 2.44 0.10 l/min, P 0.05) with no change in the time constant of the primary response (from 21.7 2.3 t