Author(s): BEHRENDT, T., BIELITZKI, R., BEHRENS, M., JAHNS, L.M., BOERSMA, M., SCHEGA, L., Institution: OTTO-VON-GUERICKE-UNIVERSITY MAGDEBURG, Country: GERMANY, Abstract-ID: 1189

INTRODUCTION:
Hypoxia and hyperoxia can affect the acute psycho-physiological response to exercise. Assessing various perceptual responses to exercise is of particular importance for investigating behavioural changes to physical activity, 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. Nevertheless, data on the acute psycho-physiological responses to exercise under intermittent hypoxia-hyperoxia (IHHT) is still lacking. Therefore, this study aimed to compare the acute perceptual and physiological responses to aerobic exercise under intermittent hypoxia-hyperoxia, hypoxia-normoxia (IHT), and sustained normoxia (NOR) in young recreational active healthy males.
METHODS:
Using a randomized, controlled, single-blinded, crossover design, 15 males (age: 24.5±4.2yrs) performed 40min of submaximal constant-load cycling (at 60% peak oxygen uptake, 80rpm) under IHHT (5x4min hypoxia and hyperoxia), IHT (5x4min hypoxia and normoxia) and NOR. Inspiratory fraction of oxygen during hypoxia and hyperoxia was set to 14% and 40%, respectively. Heart rate (HR) and muscle oxygenation (right vastus lateralis) were continuously recorded during cycling. Participants’ peripheral oxygen saturation (SpO2), perceived motor fatigue, effort perception, perceived physical strain, affective valence, arousal, motivation to exercise, and conflict to continue exercise were surveyed prior, during (every 4min period), and after cycling. Prior to and after exercise, peripheral blood lactate concentration (BLC) was determined. Exercise enjoyment was ascertained after cycling. For statistical analysis, repeated measures analyses of variance were conducted.
RESULTS:
No differences in the acute perceptual responses and exercise enjoyment were found between conditions (p≥.059, ηp²≤0.18). SpO2 was higher during the hyperoxic periods in the IHHT compared to the normoxic periods in the IHT (p<.001, ηp²=0.91). HR was higher during the hypoxic periods in the IHT compared to NOR (p=.005, ηp²=0.33). Moreover, BLC increased and was higher after IHT compared to NOR (p=.033, ηp²=0.28). No differences between conditions were found for vastus lateralis muscle oxygenation (p≥.093, ηp²≤0.16).
CONCLUSION:
IHT is associated with a higher physiological response (i.e., greater HR) and metabolic stress (i.e., greater BLC), while IHHT did not lead to an increase in HR and BLC. In addition, compared to IHT, IHHT seems to improve reoxygenation indicated by a higher SpO2 during the hyperoxic periods. However, there were no differences in perceptual responses and ratings of activity enjoyment between conditions. These results suggest that replacing normoxic by hyperoxic 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 healthy males.