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Timing Carbohydrate Beverage Intake During Prolonged Moderate Intensity Exercise Does Not Affect Cycling Performance
George G Schweitzer1, John D Smith2, James D Lecheminant3
1Muscle Biology Laboratory, Division of Kinesiology, University of Michigan, Ann Arbor, MI, USA.
Timing carbohydrate intake during prolonged cycling did not impact performance. Whether participants consumed carbohydrates continually, front-loaded, or end-loaded, the overall work output remained the same in the final time trial.
Area of Science:
- Sports Science
- Exercise Physiology
- Nutritional Science
Background:
- Carbohydrate intake during prolonged exercise can reduce fatigue and enhance performance.
- Optimal timing for carbohydrate ingestion during endurance exercise remains unclear.
Purpose of the Study:
- To investigate the effect of different carbohydrate ingestion timings on exercise performance in cyclists.
- To compare continual loading (CL), front-loading (FL), and end-loading (EL) strategies.
Main Methods:
- Ten trained cyclists performed three 2-hour cycling bouts at ~67% VO2 max, followed by a 15-minute all-out time trial.
- Carbohydrate (75g) or placebo beverages were ingested based on CL, FL, or EL protocols.
- Performance was assessed by work output during the time trial; blood glucose levels were monitored.
Main Results:
- No significant differences in work output were observed among the CL, FL, and EL conditions during the time trial.
- Peak blood glucose levels varied, being highest in FL during the first hour and EL during the second hour.
- Post-exercise blood glucose levels were similar across all ingestion timing conditions.
Conclusions:
- The timing of carbohydrate beverage consumption during prolonged, moderate-intensity cycling does not significantly alter exercise performance.
- Blood glucose responses differ based on ingestion timing, but this does not translate to performance changes in this context.
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