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Published on: March 23, 2022
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Exogenous glucose oxidation during endurance exercise under low energy availability.
Chihiro Kojima1, Aya Ishibashi2, Kumiko Ebi3
1Japan Institute of Sports Sciences, Nishigaoka, Kitaku, Tokyo, Japan.
Plos One
|October 12, 2022
Summary
Low energy availability (EA) during endurance exercise reduces carbohydrate oxidation but does not affect exogenous glucose oxidation. This finding is crucial for athletes managing energy intake and performance.
Area of Science:
- Exercise Physiology
- Nutritional Biochemistry
- Sports Science
Background:
- Energy availability (EA) is critical for regulating metabolic processes during exercise.
- Understanding the impact of low EA on fuel utilization is essential for optimizing athletic performance and health.
- Exogenous glucose oxidation serves as a key indicator of carbohydrate utilization during physical activity.
Purpose of the Study:
- To investigate the effect of low energy availability (EA) on exogenous glucose oxidation during prolonged endurance exercise.
- To compare substrate utilization, specifically carbohydrate oxidation, under conditions of low versus normal EA.
- To assess the impact of a single day of low EA endurance training on hormonal and metabolic markers.
Main Methods:
- Ten active males completed two randomized trials: low EA (19.9 kcal/kg FFM/day) and normal EA (46.4 kcal/kg FFM/day) over two consecutive days.
- Endurance training involved 60 minutes of treadmill running at 70% maximal oxygen uptake on both days.
- Exogenous glucose oxidation was measured on day 2 using 13C-labeled glucose, with respiratory gas analysis and blood sampling.
Main Results:
- Body weight significantly decreased in the low EA trial.
- Respiratory exchange ratio and systemic carbohydrate oxidation were significantly lower in the low EA trial compared to the normal EA trial.
- Despite reduced carbohydrate oxidation, exogenous glucose oxidation, measured by 13C excretion, remained unchanged between the low EA and normal EA trials.
Conclusions:
- Low energy availability during endurance exercise significantly reduces systemic carbohydrate oxidation.
- Exogenous glucose oxidation is maintained even under conditions of low energy availability, suggesting preferential utilization of ingested carbohydrates.
- These findings highlight the complex metabolic adaptations to low EA and have implications for nutritional strategies in endurance athletes.
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