B-13M Free Communication/Poster Fat Metabolism
The purpose of this study was to examine differences in fuel utilization (RER) during graded walking at moderate altitude (1592 m) and simulated sea level (FIO2 25%).
Twenty male and female subjects (mean ±SD, age: 28 ± yrs; height: 171 ± cm; weight: 67.8 ± 18.1 kg) completed two, randomized testing sessions under normobaric normoxia (NN) and normobaric hyperoxia (NH). VO2 and RER were measured while subjects walked 1.9 mph at eight separate grades (0, 5, 10, 15, 18, 21, 24, 27). Steady state VO2 and RER values were averaged during the last 2 min of each stage and compared between the NN and NH trials.
VO2 was significantly higher (p < 0.05) during NH compared to NN at all, except for one, of the walking grades (10%). RER values were significantly lower (p < 0.05) during NH at all walking grades (0–27%) when compared to NN.
Decreased RER values were associated with increased VO2 values during hyperoxia at each submaximal workload compared to normoxia. This finding has been reported in previous research and has been interpreted to signify an increased lipid utilization to maintain ATP resynthesis and muscle contraction during hyperoxia conditions. We hypothesize that the decrease in RER during hyperoxia may indicate a glycogen sparing benefit associated with living and training at moderate altitude.