Influence of priming exercise on pulmonary O2 uptake kinetics during transitions to high-intensity exercise at extreme pedal rates.
We investigated the pedal rate dependency of the effect of priming exercise on pulmonary oxygen uptake (Vo(2)) kinetics. Seven healthy men completed two, 6-min bouts of high-intensity cycle exercise (separated by 6 min of rest) using different combinations of extreme pedal rates for the priming and criterion exercise bouts (i.e., 35-->35, 35-->115, 115-->35, and 115-->115 rev/min). Pulmonary gas exchange and heart rate were measured breath-by-breath, and muscle oxygenation was assessed using near-infrared spectroscopy. When the priming bout was performed at 35 rev/min (35-->35 and 35-->115 conditions), the phase II Vo(2) time constant (tau) was not significantly altered (bout 1: 31 +/- 7 vs. bout 2: 30 +/- 5 s and bout 1: 48 +/- 16 vs. bout 2: 46 +/- 21 s, respectively). However, when the priming bout was performed at 115 rev/min (115-->35 and 115-->115 conditions), the phase II tau was significantly reduced (bout 1: 31 +/- 7 vs. bout 2: 26 +/- 5 s and bout 1: 48 +/- 16 vs. bout 2: 39 +/- 9 s, respectively, P < 0.05). Muscle oxygenation was significantly higher after priming exercise in all four conditions, but significant effects on Vo(2) kinetics were only evident when muscle O(2) extraction (measured as Delta[deoxyhemoglobin]/DeltaVo(2)) was elevated in the fundamental response phase. These data indicate that prior high-intensity exercise at a high pedal rate can speed Vo(2) kinetics during subsequent high-intensity exercise, presumably through specific priming effects on type II muscle fibers.
DiMenna
Fred J
FJ
University of Exeter, Exeter, Devon, EX1 2LU UK.
Wilkerson
Daryl P
DP
Burnley
Mark
M
Bailey
Stephen J
SJ
Jones
Andrew M
AM
D000328:Adult; D001642:Bicycling; D015444:Exercise; D006339:Heart Rate; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D008297:Male; D009119:Muscle Contraction; D018656:Muscle Fibers, Fast-Twitch / Q000378:metabolism; D018482:Muscle, Skeletal / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism*; D010101:Oxygen Consumption; D012123:Pulmonary Ventilation; D013055:Spectrophotometry, Infrared; D055815:Young Adult
D006454:Hemoglobins; C100003:deoxyhemoglobin; D010100:Oxygen