Background: Hypoxia is an environmental condition that occurs in sports performed at high altitude. Adaptation to hypoxia is accompanied by changes in body composition and cardiac function that could impair sport performance in altitude. These changes concern mainly to a reduction in muscle mass and an increased heart rate. In this context, a resistance training protocol in a normobaric hypoxia chamber has been implemented. Therefore, the aim of this study was to study the changes in body composition and cardiovascular variables after a training period in intermittent hypoxia.
Methods: A single-blind experimental study was carried out for 3 weeks. Thirty-two participants were distributed in a control group resistance training in normoxia (N) at sea level and an experimental group resistance training in intermittent hypoxia (IH) between a simulated 5100-5800m during 15 sessions with a controlled diet. Anthropometry according to ISAK was used to determine body composition. Systolic and diastolic blood pressures and other cardiovascular parameters were monitored.
Results: IH showed a reduction in body fat (from 8.9±1.9% to 8.2±1.7%) compared to N (from 8.4±1.5% to 8.1±1.4%) (P<0.001). In addition, significant changes in blood pressure were observed at the end compared to the beginning of the intervention in the IH (from 124.7±10.2 to 116.9±8.3 mmHg and 68.3±8.8 to 62.4±5.7 mmHg in systolic a diastolic blood pressure respectively). In addition, resting heart rate was significantly reduced in IH. However, partial oxygen saturation displayed no changes in both groups.
Conclusions: Altogether, the training protocol in intermittent hypoxia performed in the present report allowed to adjust body weight through fat mass reduction but maintaining muscle mass. In addition, a decrease in blood pressure and basal heart rate was observed.