Effects of Prior Voluntary Hyperventilation on the 3-min All-Out Cycling Test in Men

INTRODUCTION: The ergogenic effects of respiratory alkalosis induced by prior voluntary hyperventilation (VH) are controversial. This study examined the effects of prior VH on derived parameters from the 3-min all-out cycling test (3MT).

METHODS: Eleven men ([Combining Dot Above]V˙O2max = 46 ± 8 mL⋅kg-1⋅min-1) performed a 3MT preceded by 15-min of rest (CONT) or voluntary hyperventilation (V˙E = 38 ± 5 L⋅min-1) with PETCO2 reduced to 21 ± 1 mmHg (HYP). End-test power (EP; synonymous with critical power) was calculated as the mean power output over the last 30-s of the 3MT, and the work done above EP (WEP; synonymous with W') was calculated as the power-time integral above EP.

RESULTS: At the start of the 3MT, capillary blood PCO2 and [H+] were lower in HYP (25.2 ± 3.0 mmHg, 27.1 ± 2.6 nmol⋅L-1) than CONT (43.2 ± 2.0 mmHg, 40.0 ± 1.5 nmol⋅L-1) (P < 0.001). At the end of the 3MT, blood PCO2 was still lower in HYP (35.7 ± 5.4 mmHg) than CONT (40.6 ± 5.0 mmHg) (P < 0.001). WEP was 10% higher in HYP (19.4 ± 7.0 kJ) than CONT (17.6 ± 6.4 kJ) (P = 0.006), whereas EP was 5% lower in HYP (246 ± 69 W) than CONT (260 ± 74 W) (P = 0.007). The ΔWEP (J·kg-1) between CONT and HYP correlated positively with the PCO2 immediately before the 3MT in HYP (r = 0.77, P = 0.006).

CONCLUSION: These findings suggest that acid-base changes elicited by prior voluntary hyperventilation increase WEP but decrease EP during the all-out 3MT.