There are many potential reasons to supplement with protein and carbohydrate around workouts. Clearly protein is critical for stimulating protein synthesis and an anabolic environment to enhance recovery. New research has shown another benefit of protein and carbohydrate supplements on responses to resistance training. Reporting in the latest issue of the Journal of Strength and Conditioning Research, researchers from the University of Texas examined whether protein and carbohydrate could affect markers of muscle damage after resistance exercise. Subjects in this study ingested a supplement containing both carbs and protein or a placebo before, during and after an acute bout of resistance exercise. Blood was drawn at several time points post-exercise for creatine kinase and myoglobin, both indicators of muscle damage. Myoglobin increases rapidly after a workout whereas creatine kinase increases much later, both are indicative of damage to the membrane surrounding muscle fibers. Myoglobin levels peaked 1 hour after exercise and were significantly reduced in the protein-carbohydrate group. Creatine kinase was also reduced more in the protein-carbohydrate group 24 hours after exercise. The supplement also resulted in increased insulin and reduced cortisol levels compared to placebo at several time points. The findings highlight the importance of ingesting protein and carbohydrate around a workout in order to promote optimal recovery.

Baty JJ, Hwang H, Ding Z, Bernard JR, Wang B, Kwon B, Ivy JL. The effect of a carbohydrate and protein supplement on resistance exercise performance, hormonal response, and muscle damage. J Strength Cond Res. 2007 May;21(2):321-9.