Why the study?
The study investigated submaximal exercise responses during acute exposure to normobaric hypoxia versus hypobaric hypoxia across different exercise intensities.
Does acute exposure to normobaric hypoxia compared to hypobaric hypoxia alter cardiorespiratory and metabolic responses during graded submaximal exercise in recreationally trained males?
Does acute exposure to normobaric hypoxia compared to hypobaric hypoxia alter cardiorespiratory and metabolic responses during graded submaximal exercise in recreationally trained males?
Acute exposure to normobaric hypoxia produces equivalent cardiorespiratory responses to hypobaric hypoxia during submaximal exercise, though lactate accumulation may differ.
Normobaric hypoxia yields largely equivalent cardiorespiratory responses during submaximal exercise; leaves open whether minor ventilatory and lactate differences matter for altitude training.
Background: The study investigated submaximal exercise responses during an acute exposure to normobaric hypoxia (NH) versus hypobaric hypoxia (HH) focusing on different exercise intensities. Methods: Eight recreationally trained male subjects (age 23 ± 3 years) performed submaximal cycling exercise at three different intensity levels (100, 150, and 200 W) in NH (simulated altitude 3150 m) and HH (terrestrial high altitude, 3150 m) in a cross-over study design. Cardiorespiratory parameter, blood lactate concentration, and ratings of perceived exertion were determined at each intensity level. Results: Cardiorespiratory parameters, arterial oxygen saturation, and ratings of perceived exertion did not differ between NH and HH except for the higher ventilatory equivalent for oxygen in HH compared to NH (25.9 ± 1.3 vs. 24.6 ± 1.0 at 100 W, 28.0 ± 1.6 vs. 27.1 ± 1.6 at 150 W, 32.1 ± 3.9 vs. 31.3 ± 3.6 at 200 W, p = 0.03). Blood lactate concentration tended to be higher in HH compared to NH (1.8 ± 0.9 mmol/L vs. 1.7 ± 0.8 mmol/L at 100 W, 3.2 ± 1.8 mmol/L vs. 2.8 ± 1.6 mmol/L at 150 W, 6.0 ± 3.1 mmol/L vs. 5.5 ± 3.0 mmol/L at 200 W, p = 0.08) with a significant interaction effect for exercise intensity (p = 0.02). Conclusions: Cycling during acute exposure to NH appears to result in equivalent cardiorespiratory responses to HH. The more pronounced lactate accumulation in HH should be a topic of future research.
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Faulhaber et al. (2020) studied this question.
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