Efficacy of Normobaric Intermittent Hypoxic Training to Improve VO2peak During Acute Hypobaric Hypoxia Exposure

Abstract

Environmental conditions pose additional threats to the health of soldiers during military operations. Missions conducted at high altitude increase the relative workload for military personnel and unacclimatized warfighters may endure performance decrements. PURPOSE: To examine the effects of normobaric intermittent hypoxic training (NIHT), when compared to normobaric normoxia (NN) training, on peak aerobic capacity (VO2peak) in hypobaric hypoxia (HH). METHODS: Eleven male Reserve Officers’ Training Corps (ROTC) cadets (age 19.55±1.44 y, mass 75.80±8.82 kg, stature 177.45±6.67 cm) completed the 6 week training intervention in either the NIHT (EXP, n=6) or NN (CON, n=5) conditions. Pre- and post-assessment of VO2peak was conducted in an HH setting equivalent to 3033 m. The EXP group also completed a follow-up VO2peak assessment after a 1 week detraining period. Mixed ANOVA was performed to analyze differences between the within-subjects factor (time) and between-subjects factor (group). Repeated measures ANOVA were also performed to analyze differences between the pre-, post-, and follow-up results of the EXP group. RESULTS: There was no significant interaction of time x group, F(1,9)=1.17, P=0.31, partial ή2=0.12, nor significant main effect of group, F(1,9)=0.03, P = 0.86, nor was there a significant main effect of time F(1,9)=3.35, P=0.10, on time-to-exhaustion (TE) measured in HH. Neither was there a significant interaction of time x group for relative VO2peak (RVO2peak), F(1,9)=164, P=0.23, partial ή2=0.15. Further, there was no significant main effect of group for RVO2peak, F(1,9) = 0.61, P=0.45. However, there was a significant main effect of time for RVO2peak, F(1,9)=6.88, P=0.03. Finally, there was no significant difference of RVO2peak in the EXP group between pre-, post-, and follow-up assessments in the HH chamber, F(2,3)=6.53, P=0.06. CONCLUSION: NIHT, compared to NN, failed to elicit significantly greater aerobic endurance enhancements in acute HH. However, while statistical significance for TE, VO2peak, and RVO2peak may not have been attained, moderate effect sizes for the aforementioned variables reveal a potential practical significance was achieved via increases of 7.37%, 15.99%, and 14.71% for the EXP group, respectively. Supported by NSCA Foundation Doctoral Research Grant