Resumen de Two Days of Hypoxic Exposure Increased Ventilation Without Affecting Performance
Sébastien Racinais, Grégoire Millet, Chikei Li, Bronwen Masters, Justin Grantham
The aim of this study was to test the short-term effects of using hypoxic rooms before a simulated running event. Thirteen subjects (29 ± 4 years) lived in a hypoxic dormitory (1,800 m) for either 2 nights (n = 6) or 2 days + nights (n = 7) before performing a 1,500-m treadmill test. Performance, expired gases, and muscle electrical activity were recorded and compared with a control session performed 1 week before or after the altitude session (random order). Arterial blood samples were collected before and after altitude exposure. Arterial pH and hemoglobin concentration increased (p < 0.05) and PCO2 decreased (p < 0.05) upon exiting the room. However, these parameters returned (p < 0.05) to basal levels within a few hours. During exercise, mean ventilation (VE) was higher (p < 0.05) after 2 nights or days + nights of moderate altitude exposure (113.0 ± 27.2 L·min-1) than in the control run (108.6 ± 27.8 L·min-1), without any modification in performance (360 ± 45 vs. 360 ± 42 seconds, respectively) or muscle electrical activity. This elevated VE during the run after the hypoxic exposure was probably because of the subsistence effects of the hypoxic ventilatory response. However, from a practical point of view, although the use of a normobaric simulating altitude chamber exposure induced some hematological adaptations, these disappeared within a few hours and failed to provide any benefit during the subsequent 1,500-m run.
