Acute psycho-physiological responses to submaximal constant-load cycling under intermittent hypoxia-hyperoxia vs. hypoxia-normoxia in young males

Hypoxia and hyperoxia can affect the acute psycho-physiological response to exercise. Recording various perceptual responses to exercise is of particular importance for investigating behavioural changes to physical activity towards health, given that the perception of exercise-induced pain, discomfort or unpleasure, and a low level of exercise enjoyment are commonly associated with a low adherence to physical activity. Therefore, this study aimed to compare the acute perceptual (i.e., ratings of perceived motor fatigue, effort perception, perceived physical strain, affective valence, arousal, motivation to exercise, conflict to continue exercise, and activity enjoyment) and physiological responses (i.e., heart rate (HR), capillary blood lactate concentration (BLC), peripheral blood oxygenation (S p O 2 ), total tissue (tHb) and oxygenated haemoglobin concentration (S m O 2 ) of the vastus lateralis muscle) to 40 min constant-load cycling (60% peak oxygen uptake) under intermittent hypoxia-hyperoxia (IHHT), hypoxia-normoxia (IHT), and sustained normoxia (NOR) in young recreational active healthy males. No differences in the acute perceptual responses were found between conditions (p ≥ 0.059, η p ²≤0.18), while the physiological responses differed. Accordingly, S p O 2 was higher during hyperoxia and normoxia in IHHT compared to IHT (p < 0.001, η p ²=0.91), respectively. Moreover, HR (p = 0.005, η p ²=0.33) and BLC (p = 0.033, η p ²=0.28) were higher during IHT compared to NOR. No differences between conditions were found for percentual changes in tHb and S m O 2 of the vastus lateralis. These results suggest that replacing normoxic by hyperoxic reoxygenation-periods during submaximal constant-load cycling under intermittent hypoxia reduced the exercise-related physiological stress but had no effect on perceptual responses and perceived activity enjoyment in young recreational active healthy males.