Journal of Men’s Health (JOMH) is published by IMR Press from Volume 17 Issue 1 (2021). Previous articles were published by another publisher on a subscription basis, and they are hosted by IMR Press on imrpress.com as a courtesy and upon agreement with Dougmar Publishing Group.
EFFECTS OF VARIOUS HYPOBARIC HYPOXIA ON METABOLIC RESPONSE, SKELETAL MUSCLE OXYGENATION, AND EXERCISE PERFORMANCE IN HEALTHY MALES
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This study aimed to evaluate the effect of various levels of hypoxia versus normoxia on exercise perfor-mance, measured by metabolic parameters and skeletal muscle oxygenation profiles during graded exercise test (GXT) in healthy men.
In this randomized crossover trial, 11 healthy male participants (age 21.5 ± 2.3 years) performed the GXT using a cycle ergometer at sea-level (760 torr) and at various hypobaric hypoxia: 633, 526, and 433 torr, corresponding to simulated altitudes of 1500, 3000, and 4500 m, respectively. The GXT was started at 50 W and increased by 25 W every 2 min until the participants were exhausted. The pedal frequency was set to 60 rpm. Metabolic parameters (heart rate, HR; minute ventilation, VE; carbon dioxide excretion, VCO2; respiratory exchange ratio, RER; peripheral capillary saturation, SpO2; oxygen consumption, VO2; and blood lactate, O2 pulse) and skeletal muscle oxygen profiles (oxygenated hemoglobin and myoglobin, OxyHb; deoxygenated hemoglobin and myoglobin, DeoxyHb; and tissue oxygen saturation, StO2) were measured for every 2 min during the GXT. Exercise performance was evaluated by maximal oxygen con-sumption, peak power, and duration of exercise time obtained through GXT.
Regarding metabolic parameters, HR (P < 0.05), VE, (P < 0.05), VCO2 (P < 0.05), RER (P < 0.05), and blood lactate (P < 0.05) showed significant increase under hypoxia compared to normoxia. Moreover, the increase was more pronounced as hypoxia became more severe. However, the SPO2 (P < 0.05) and O2 pulse (P < 0.05) presented a significant decrease under hypoxia compared to normoxia. Similarly, the decrease was more pronounced as hypoxia became more severe. VO2 (P > 0.05) did not show significant difference under different environmental conditions. In skeletal muscle oxygen profiles, none of the param-eters showed noticeable changes. Regarding exercise performance, VO2max (P < 0.05) and exercise time (P < 0.05) decreased significantly as hypoxia became more severe, and peak power (P < 0.05) decreased significantly at simulated altitudes of 3000 and 4500 m compared to normoxia.
A decrease in exercise performance is due to a decrease in metabolic function under various hypoxia compared to normoxia and the decrease was more pronounced as hypoxia became more severe.