What effect does short-term moderate hypoxia exposure during constant workload exercise have on post exposure measurements of resting substrate partitioning?

Kelly, Liam P. (2015) What effect does short-term moderate hypoxia exposure during constant workload exercise have on post exposure measurements of resting substrate partitioning? Masters thesis, Memorial University of Newfoundland.

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Abstract

Recent studies have shown a potentiation effect of exercise performed under moderate short-term hypoxia on weight loss. From these data, it has been hypothesized that moderate hypoxia exposure affects substrate utilization and that normobaric hypoxia training might be an effective means to induce weight loss. However, limited data is currently available on resting substrate partitioning after a single bout of exercise performed under hypoxia. The purpose of the current study was therefore to asses the viability of moderate short-term hypoxia exposure during constant workload exercise as a means to alter post exposure resting substrate partitioning. Respirometry measurements were recorded at baseline (BMRpre), during 60-min constant workload exercise (under normoxia N-CWE; and hypoxia H-CWE ) and during post exposure resting metabolic measurements; recorded immediately after exercise (PEMR, 0-60-min) and again the next morning (BMRpost). Compared to baseline, lipid oxidation was significantly elevated and carbohydrate oxidation suppressed during PEMR (p=0.010 and p=0.076, respectively) and BMRpost (p=0.036 and p=0.010, respectively) after H-CWE. When the same absolute workload was performed under normoxia, no effect on resting substrate partitioning was observed during the post exercise recording periods. An increased reliance on endogenous carbohydrate sources during H-CWE compared to N-CWE is suggested to explain the current findings. In conclusion, a single bout of exercise performed under moderate short-term hypoxia is associated with a shift in resting substrate partitioning toward an increased lipid oxidation up to 22-hr post exposure.

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