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Pre-exercise feeding does not affect endurance cycle exercise but attenuates post-exercise starvation-like response.
J Calles-Escandón1, J T Devlin, W Whitcomb
1Metabolic Unit, University of Vermont, Burlington 05405.
Medicine and Science in Sports and Exercise
|July 1, 1991
Summary
Consuming mixed-snack food (CB) or fructose (FRU) before exercise increased pre-exercise glucose and insulin. However, endurance and substrate oxidation during exercise remained unchanged, with a shift towards lipid oxidation during recovery after placebo (PBO).
Area of Science:
- Exercise Physiology
- Sports Nutrition
- Metabolic Studies
Background:
- Pre-exercise nutrition significantly impacts metabolic responses during and after exercise.
- Understanding substrate utilization shifts based on pre-exercise fuel sources is crucial for optimizing athletic performance and recovery.
Purpose of the Study:
- To investigate the metabolic effects of ingesting a mixed-snack food (CB), fructose (FRU), or placebo (PBO) before moderate-intensity cycle exercise.
- To compare substrate and hormone responses during and after exercise across different pre-exercise nutritional conditions.
Main Methods:
- Eight healthy volunteers with varying peak VO2 underwent a randomized Latin-square design study.
- Subjects consumed CB, FRU, or PBO 30 minutes prior to cycling to exhaustion at 70% peak VO2.
- Metabolic parameters, including gas exchange, blood samples, substrate, and hormone concentrations, were measured before, during, and post-exercise.
Main Results:
- CB and FRU elevated pre-exercise glucose and insulin levels; FRU significantly increased blood lactate.
- No significant differences were observed in endurance time, substrate utilization, or hormone levels during exercise.
- Post-exercise recovery showed a greater reliance on lipid oxidation and reduced carbohydrate oxidation following PBO compared to CB or FRU.
Conclusions:
- Pre-exercise ingestion of CB or FRU does not enhance endurance or alter substrate oxidation during moderate-intensity exercise.
- Nutritional strategies influence post-exercise substrate utilization patterns, with carbohydrate-based meals promoting greater carbohydrate oxidation during recovery.