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1School of Sport and Health Sciences, St. Luke's Campus, University of Exeter, Heavitree Road, Exeter, Devon; and 2Department of Sport and Exercise Science, Aberystwyth University, Ceredigion, United Kingdom
Submitted 6 September 2008 ; accepted in final form 27 November 2008
We investigated the pedal rate dependency of the effect of priming exercise on pulmonary oxygen uptake (
O2) 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
O2 time constant (
) 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
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
O2 kinetics were only evident when muscle O2 extraction (measured as
[deoxyhemoglobin]/
O2) was elevated in the fundamental response phase. These data indicate that prior high-intensity exercise at a high pedal rate can speed
O2 kinetics during subsequent high-intensity exercise, presumably through specific priming effects on type II muscle fibers.
O2 kinetics; phase II time constant;
O2 slow component; prior exercise; cadence
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