The effects of breath holding during high-intensity land-based ergometry in swimmers

The aim of this study was to compare cardiorespiratory responses during high-intensity land-based exercise between free-breathing and breath-holding conditions in swimmers. Twenty varsity swimmers (20 ± 2 years, 10 females) performed 20 s bouts of simultaneous arm and leg ergometry exercise at high intensity (total power output = 606 ± 76 W). Heart rate (HR), muscle deoxygenation ([HHb]) and total hemoglobin ([THb]) at the triceps and vastus lateralis, and gas exchange and ventilatory variables were recorded continuously. Blood pressure and lactate were measured pre- and post-exercise. Exercise HR was higher under the breath-holding condition (free-breathing [FB] = 118 ± 14 bpm, breath-holding [BH] = 131 ± 17 bpm; p = 0.001) as were post-exercise blood pressures (systolic: FB = 141 ± 14 mmHg, BH = 156 ± 16 mmHg, p = 0.002; diastolic: FB = 71 ± 14 mmHg, BH = 79 ± 9 mmHg; p = 0.01, respectively). During exercise, muscle [THb] was higher under the breath-holding condition (FB = -1.6 ± 2.7 μM, BH = -0.3 ± 1.6 μM; p = 0.01). No between-condition differences in post-exercise blood lactate (FB = 8.8 ± 1.8 mmol.L^-1, BH = 9.2 ± 3.9 mmol.L^-1; p = 0.63) or [HHb] (FB = 2.9 ± 2.6 μM, BH = 3.4 ± 2.2 μM; p = 0.39) were observed. These data suggest that the exercise response prevailed over the breath-holding response during high-intensity land-based exercise in swimmers and that intrinsic oxygen stores may have been sufficient to sustain the aerobic energy contribution during 20 s high-intensity exercise while breath holding.