RT  - Journal of Men's Health
ID  - 10.31083/jomh.v16i4.312
T1  - EFFECTS OF VARIOUS HYPOBARIC HYPOXIA ON METABOLIC RESPONSE, SKELETAL MUSCLE OXYGENATION, AND EXERCISE PERFORMANCE IN HEALTHY MALES
A1  - Jong-Beom Seo
A1  - Sung-Woo Kim
A1  - Won-Sang Jung
A1  - Hun-Young Park
A1  - Kiwon Lim
K1  - exercise performance; graded exercise test; hypoxia; metabolic function; NIRS; skeletal muscle oxygenation
YR  - 2020
SP  - 107
AB  - <p class="ql-align-justify"><strong>Objective</strong></p><p class="ql-align-justify">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.</p><p class="ql-align-justify"><strong>Methods</strong></p><p class="ql-align-justify">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.</p><p class="ql-align-justify"><strong>Results</strong></p><p class="ql-align-justify">Regarding metabolic parameters, HR (P &lt; 0.05), VE, (P &lt; 0.05), VCO2 (P &lt; 0.05), RER (P &lt; 0.05), and blood lactate (P &lt; 0.05) showed significant increase under hypoxia compared to normoxia. Moreover,&nbsp;the increase was more pronounced as hypoxia became more severe. However, the SPO2 (P &lt; 0.05) and O2 pulse (P &lt; 0.05) presented a significant decrease under hypoxia compared to normoxia. Similarly, the decrease was more pronounced as hypoxia became more severe. VO2 (P &gt; 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 &lt; 0.05) and exercise time (P &lt; 0.05) decreased significantly as hypoxia became more severe, and peak power (P &lt; 0.05) decreased significantly at simulated altitudes of 3000 and 4500 m compared to normoxia.</p><p class="ql-align-justify"><strong>Conclusion</strong></p><p class="ql-align-justify">A decrease in exercise performance is due to a decrease in metabolic function under various hypoxia&nbsp;compared to normoxia and the decrease was more pronounced as hypoxia became more severe.</p>