G-43b Free Communication/Poster - Late-Breaking Abstracts Saturday, June 1, 2019, 7: 30 AM - 11: 00 AM Room: CC-Hall WA2
There are areas in the world where elevated temperatures occur at relatively high altitudes. Exposure to heat or altitude typically induces an increase in intracellular heat shock protein 70 (iHSP70) and hypoxia-inducible factor-1α (iHIF-1α), which have beneficial down-stream physiological effects. However, the responses to the combination of these environments are unclear.
PURPOSE: To determine the impact of combined acute exposure to heat and altitude on iHSP70 and iHIF-1α.
METHODS: Using a randomized, cross-over study design, 10 men (mean ± SD; age: 25 ± 7 yr; weight: 88 ± 13 kg; height: 180 ± 6 cm; sea level (SL) VO2peak: 42 ± 5 ml.kg-1.min-1) were exposed to four environmental conditions separated by at least one week: (1) SL thermoneutral (SLTN; 250m, 20°C, 30-50% rh); (2) SL hot (SLH; 250m, 35°C, 30% rh); (3) altitude thermoneutral (ATN; 3000m, 20°C, 30-50% rh); and (4) altitude hot (AH; 3000m, 35°C, 30% rh). Blood samples were collected at SL (baseline, BL) prior to ˜1.5 hour environmental equilibration period and again immediately Pre- and Post- 30 minute of steady state (SS) exercise (cycling, 50% of SL VO2peak). iHSP70 and iHIF-1α were measured from peripheral blood mononuclear cells. The percent change (% Δ) from BL to Pre- and PostSS was analyzed with 2 x 4 (% Δ BL to Pre- and PostSS x environment) RM ANOVA.
RESULTS: iHSP70: there was an effect of exercise (PreSS: 4.4 ± 7.6% vs PostSS: 17.5 ± 9.6%, p < 0.05), but no effect of environment (p > 0.05) or an exercise x environment interaction (p > 0.05). iHIF-1α: there was no effect for exercise (p > 0.05), environment (p > 0.05), or an exercise x environment interaction (p > 0.05).
CONCLUSION: Our results indicate that iHSP70 increased in response to SS exercise while iHIF1α was unaltered in these testing conditions. The combination of heat and altitude did not result in an even greater protein expression when compared to exercise alone. However, it is plausible that a more severe environmental stress and/or higher exercise intensity (>50% SL VO2peak) would result in elevated cellular response compared to a single environment.
Funded by USAMRMC; authors views not official US Army or DOD policy.