Impact of Respiratory Muscle Training on Exercise Tolerance in Hypobaric Hypoxia

Abstract

Hypoxia and certain chronic diseases can intensify the work of breathing, potentially impacting the muscle hyperemic response during exercise and overall exercise performance. Respiratory muscle training (RMT) has been observed to decrease perceived effort under hypoxic conditions; however, it remains unclear if RMT boosts exercise performance in acute hypoxia. We investigated whether 4 weeks of RMT could enhance maximal and submaximal exercise performance in hypoxia (PB=425 mmHg, ~4876 m). Seven adult males underwent a 250 kJ submaximal (RPE 15-17) cycling trial in hypoxia, followed by an incremental test to maximal exertion. After 4 weeks of RMT under normoxic conditions, these tests were repeated in hypoxia. Although six of the participants displayed improvements in submaximal exercise performance, these numerical differences failed to reach statistical significance. However, RMT did raise VO2max peak power (Pre-RMT: 242.62 ± 35, Post-RMT: 251.85 ± 38 W, p=0.04). Moreover, even with an increased HR during the submaximal exercise trial after RMT (Pre-RMT:154.14 ± 16, Post-RMT: 160.86 ± 12, p<0.05), the RPE showed no significant difference during the test (Pre-RMT: 17.43 ± 0.79, Post-RMT: 17.43 ± 0.53, P>0.05). Despite this, no substantial increase in hypoxic submaximal exercise performance was observed, likely due to the small sample size. These findings suggest RMT might increase hypoxic exercise tolerance by reducing perceived exertion for a given HR. This work was supported by funding from the United States Special Operations Command (USSOCOM) and the National Institutes of Health (2L30HL134123-03). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.