The physiological effects of breath-holding during high-intensity exercise

The purpose of this study was to determine the physiological effects of breath-holding during high-intensity exercise. Twenty participants (age: 23 ± 4 years, 10 females) performed 20 s sprints of simultaneous arm and leg ergometry exercise, under free-breathing (FB) and breath-holding (BH) conditions. Identical power outputs were sustained for both breathing conditions. Heart rate was significantly higher under the breath-holding condition during exercise (FB = 118 ± 12 bpm versus BH = 131 ± 14 bpm; p < 0.001) but lower for 5 min post-exercise (FB = 110 ± 16 bpm, BH = 102 ± 15 bpm, p = 0.003). Systolic blood pressure was higher under the breath-holding condition post-exercise (FB = 142 ± 18 mmHg, BH = 151 ± 15 mmHg, p = 0.03). Muscle deoxygenated hemoglobin was unchanged between conditions during exercise (FB = 2.7 ± 1.7 μM, BH = 2.6 ± 1.7 μM, p = 0.37) and no difference in post-exercise blood lactate concentration was observed between conditions (FB = 9.3 ± 3.5 mmol.L^-1, BH = 8.2 ± 2.5 mmol.L^-1, p = 0.15). End-tidal partial pressure of oxygen was reduced (FB = 111 ± 11 mmHg, BH = 76 ± 14 mmHg, p < 0.001) and oxygen uptake was increased (FB = 2.36 ± 0.63 L.min^-1, BH = 4.52 ± 0.73 L.min^-1, p < 0.001) under the breath-holding condition immediately post-exercise. Exercise-induced tachycardia prevailed over apnea-induced bradycardia during exercise, but residual effects of breath-holding were evidenced by the observed bradycardia during recovery. These data suggest that intrinsic oxygen stores were sufficient to sustain the aerobic energy contribution during 20 s high-intensity exercise while breath-holding.