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Purpose: We investigated the effects of pre-exercise voluntary hyperventilation and the resultant hypocapnia on metabolic and cardiovascular responses during and after high-intensity exercise. Methods : Ten healthy participants performed a 60-s cycling exercise at a workload of 120% peak oxygen uptake in control (spontaneous breathing), hypocapnia and normocapnia trials. Hypocapnia was induced through 20-min pre-exercise voluntary hyperventilation. In the normocapnia trial, voluntary hyperpnea was performed with CO 2 inhalation to prevent hypocapnia. Results : Pre-exercise end-tidal CO 2 partial pressure was lower in the hypocapnia trial than the control or normocapnia trial, with similar levels in the control and normocapnia trials. Average V ˙ O 2 during the entire exercise was lower in both the hypocapnia and normocapnia trials than in the control trial (1491 ± 252vs.1662 ± 169vs.1806 ± 149 mL min -1 ), with the hypocapnia trial exhibiting a greater reduction than the normocapnia trial. Minute ventilation during exercise was lower in the hypocapnia trial than the normocapnia trial. In addition, minute ventilation during the first 10s of the exercise was lower in the normocapnia than the control trial. Pre-exercise hypocapnia also reduced heart rates and arterial blood pressures during the exercise relative to the normocapnia trial, a response that lasted through the subsequent early recovery periods, though end-tidal CO 2 partial pressure was similar in the two trials. Conclusions : Our results suggest that pre-exercise hyperpnea and the resultant hypocapnia reduce V ˙ O 2 during high-intensity exercise. Moreover, hypocapnia may contribute to voluntary hyperventilation-mediated cardiovascular responses during the exercise, and this response can persist into the subsequent recovery period, despite the return of arterial CO 2 pressure to the normocapnic level.

Purpose : We investigated whether varying the number of repetitions of high-intensity exercise during work-matched warm-ups modulates physiological responses (heart rate, metabolic responses, and core temperature), perceptions (ratings of perceived exertion, effort of breathing), readiness for exercise, and short-term exercise performance. Methods : Ten physically active young males performed a 30-s Wingate anaerobic test (WAnT) following a warm-up consisting of submaximal constant-workload cycling at 60% maximal oxygen uptake with no high-intensity cycling (constant-workload warm-up) or with 1, 4, or 7 repetitions of 10 s of high-intensity cycling at 110% maximal oxygen uptake. All warm-ups were matched for duration (10 min) and total work. Results : Warm-ups with seven repetitions of high-intensity cycling resulted in higher ratings of perceived whole-body exertion and effort of breathing than the constant-workload warm-up. Warm-up with four repetitions of high-intensity cycling produced greater readiness for a 30-s WAnT (7.33 ± 0.73 AU) than the constant-workload warm-up (6.33 ± 0.98 AU) ( P = .022). Physiological responses did not differ among the four warm-up conditions, though peak heart rate was slightly higher (~5 beats/min) during warm-up with four or seven repetitions of high-intensity cycling than during the constant-workload warm-up. Peak, mean, and minimum power output during the 30-s WAnT did not differ among the four warm-up conditions. Conclusions : These results suggest that the effects of warm-ups with intermittent high-intensity exercise on physiological responses and short-term high-intensity exercise performance do not greatly differ from a warm-up with a work-matched submaximal constant-workload. However, they appear to modulate perceptions and readiness as a function of the number of repetitions of the high-intensity exercise.