Impact of hypoxic air quality on resistance training effect in different normobaric hypoxia environments.

PURPOSE: This study compared the impact of hypoxic air quality breathing in two normobaric hypoxia (NH) environments (a tent with high carbonic levels and relative humidity [NHTent] vs. a room with normal carbonic levels and relative humidity [NHRoom]) on the outcomes of an 8-week resistance training (RT) program.

METHODS

Twenty-four trained men (age: 22 ± 3 years; weight: 76.32 ± 11.01 kg; height: 176.79 ± 7.48 cm) were assigned to either the NHTent or the NHRoom group being exposed to the same FiO2 (15.9%) to analyze the impact of two different procedures to generate intermittent NH on structural, physiological, functional, and perceptual responses after a RT program. CO2 and relative humidity levels were measured before and after each training session. Physiological variables (heart rate [HR] and SpO2) were monitored and used for comparison between the first and last training sessions. Functional (bench press and squat 1RM) and structural (vastus lateralis thickness) responses were measured before and after the program.

RESULTS

CO2 and relative humidity levels were higher in the NHTent (p < 0.001). Compared to NHRoom, NHTent group displayed higher HR (p = 0.002), lower SpO2 (p = 0.014), greater increases in 1RM (p = 0.011) and lower increases in vastus lateralis thickness (p = 0.06).

CONCLUSION

These findings suggest that the CO2 and relative humidity levels on the hypoxic air breathed during training alter the physiological response to the RT. The harsher environment seems to enhance neuromuscular adaptations but limit hypertrophic responses. Results highlight the need to control environmental factors carefully when simulating NH conditions for training purposes.