INTRO: It is known that ascent to altitude increases reliance on carbohydrates and may affect respiratory exchange rate (R). It is unknown if these adaptations occur during exercise at moderate altitudes.
PURPOSE: The purpose of this study was to determine differences in R, carbohydrate (CHO) and fat utilization in acclimated and non-acclimated participants during a trail run at moderate altitude.
METHODS: Seventeen participants volunteered and were grouped based on location of residency: acclimated (AC, living at 5800ft, N=8) and non-acclimated (NA, living at 2181ft, N=9). The trail altitude was 5385 feet at onset with 56 feet rise in elevation, and environmental condition ranges included temperature: 79.2°-90.2° F, humidity: 4.5%-8.3%, and wind speed: 1.1-3.5 mph. All measures were obtained using a CosMed K4b2 portable metabolic system. Measurements were taken mid-run and 45 seconds prior to the end of the run. Data were analyzed using independent t-tests, with significance at the p<0.05 level.
RESULTS: There were no differences between groups per variable: AC R mid run = 0.89±0.05, t15 = -.111, p = .913; NA R mid = 0.89±0.06; NA R end = 0.83±0.05, t15 = -.641, p = .531; AC R end = 0.81±0.03; AC Fat% mid = 36.9±16.3, t15 = -.083, p = .935, NA Fat% mid = 36.2±18.9; AC Fat% end =58.7±16.0, t15 = .512, p = .616, NA Fat% end = 62.3±12.5; AC CHO% mid =63.6±16.3, t15 = .242, p = .812, NA CHO% mid = 65.6±17.8; AC CHO% end = 41.8±15.7, t15 = -.512, p = .616, NA CHO% end = 38.2±12.5.
CONCLUSION: Our results indicate that acclimation to moderate altitude has no influence on respiratory exchange rate, nor Fat or CHO utilization during a one-mile trail run. Exercise of longer duration may produce different results. Overall fitness level of the participant may also influence nutrient utilization.
