Skip Navigation LinksHome > May 2003 - Volume 35 - Issue 5 > EFFECTS OF CARBOHYDRATE SUPPLEMENTATION OF PREVIOUS EXERCISE...
Medicine & Science in Sports & Exercise:
F-22C Free Communication/Slide Carbohydrate and Performance

EFFECTS OF CARBOHYDRATE SUPPLEMENTATION OF PREVIOUS EXERCISE AND RECOVERY ON FUEL UTILIZATION OF SUBSEQUENT EXERCISE

Widzer, M O.1; Boon, N1; Lichtenberg, L C.1; Ivy, J L. FACSM1

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1Department of Kinesiology, University of Texas, Austin, TX

Previous research has demonstrated that a subsequent bout of exercise performed on the same day results in an exaggerated stress hormone response and cytokine production compared with a single exercise bout and is strongly mediated by carbohydrate availability.

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PURPOSE

This study was conducted to determine the effects of carbohydrate supplementation during a previous exercise bout and 2 h of recovery on fuel utilization, stress response and performance during a subsequent exercise bout.

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METHODS

After an overnight fast, 8 trained male cyclists (75.1±3.2 kg, 60.0±1.9 ml/kg/min) completed 2 exercise trials (EX1 and EX2) in random order. EX1 consisted of 90 min of cycle ergometry at sub-lactate threshold (218.9±8.4 watts, 2.7±0.1 l/min), followed by a 2 h recovery period. During EX1 and recovery period, subjects received at predetermined times either an 8% carbohydrate supplement (CHO) or placebo (PLA). Subjects then performed a second exercise bout lasting 75 min (EX2), at the same intensity as used in EX1. Immediately following EX2, a 278.7±20.5 KJ time trial was performed. PLA was provided during EX2 to prevent dehydration.

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RESULTS

During EX1 and recovery plasma insulin levels were higher during CHO compared to PLA (p < 0.05). However, during EX2 plasma insulin and IL-6 levels were similar between treatments, but plasma free fatty acids, glycerol, cortisol and growth hormone levels were suppressed during CHO (p < 0.05). This plasma profile corresponded with a lower fat and higher carbohydrate oxidation rate during CHO compared to PLA (p < 0.05). Despite differences in substrate utilization between CHO and PLA, no difference in time trial performance was observed.

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CONCLUSION

The availability of carbohydrate during EX1 and recovery will suppress fat utilization, elevate carbohydrate utilization and suppress the rise in several hormones related to stress without a concomitant increase in IL-6. Furthermore, carbohydrate supplementation during EX1 does not enhance performance as assessed by a time trial following EX2.

©2003The American College of Sports Medicine

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