The effects of carbohydrate on inflammation following an acute bout of resistance exercise

Abstract

The immune response to inflammation involves the release of cytokines, which determine the intensity and duration of the immune response (Kuby, 1997). The cytokine interleukin-6 (IL-6), functions as a negative feedback signal that turns off pro-inflammatory mediators during the immune response. IL-6 also initiates the release of CRP, which induces inflammation. Therefore, IL-6 is known as both a pro and anti-inflammatory mediator of the immune response. IL-6 is released during the immune response to inflammation. IL-6 peaks about 8 hours after an eccentric exercise session that induces muscle damage. Carbohydrate ingestion during endurance exercise attenuates the rise in IL-6 immediately post-exercise during recovery. IL-6 along with the acute phase protein C-reactive protein (CRP) (a marker of the systemic inflammatory response), and creatine kinase (CK) (a semi-quantitative marker of muscle damage), will be used to determine the affects of eccentric exercise on muscle damage and the inflammatory response.

Purpose: To determine whether IL-6, CRP and CK, following eccentric exercise differ with a carbohydrate supplement versus a placebo. Methods: The study was a double-blind, cross-over design. Male and female subjects consumed a carbohydrate or placebo beverage the day of and day after the eccentric exercise. Subjects also consumed a controlled diet the day before, day of and the day after the exercise session. The diet consisted of 50% carbohydrate, 30% fat and 20% protein. The exercise session was two bouts of an eccentric exercise using the bicep muscle, three weeks apart, to induce muscle damage and initiate an inflammatory response. A repeated-measures ANOVA was used to determine whether carbohydrate ingestion influenced IL-6, CRP and CK. Results: Carbohydrate increased the rise in IL-6 8 hours post-exercise compared to placebo. An increase in arm circumference at 8, 12 and 120 hours and subjective soreness at 12, 24, and 48 hours post-exercise was indicative of muscle damage. Conclusion: Carbohydrate increased the local inflammatory response following resistance exercise, but had no effects on CRP and CK. This study is the first to show that carbohydrate following eccentric exercise has an effect on the local inflammatory response.