[Comparing the effects of dietary supplementation with carbohydrate and whey protein at two ratios on muscle damage indices after eccentric resistance exercise]

ABSTRACT

Delayed muscle soreness occurs after resistance activity or training involving an eccentric component, and nutrition can affect the extent of muscle injury by playing a role in both protein synthesis and catabolism. The objective of this study was to compare the effects of dietary supplementation with carbohydrate and protein at different proportions on injury indices of muscle after a session of eccentric resistance exercise. In this double-blind placebo-controlled study 24 non-athlete males [age21.5 +/- 2.4 years, height 176 +/- 4.7 cm, weight 73.6 +/- 5.4 kg, BMI 24.3 +/- 1.9 kg/m[2], body fat 16.1 +/- 2.5%] were divided randomly into 3 groups of 8, receiving a supplement of carbohydrate-plus-whey protein at a ratio of 1 3 or 1 4, or a placebo [aspartame]. Serum creatine kinase[CK] andlactate dehydrogenase[LDH] were determined photometrically, and muscle pain was measured using a standard scale of PAS before, 24 and 48 hours after, an eccentric resistance exercise involving knee flexion. Both carbohydrate-plus-whey protein supplements caused statistically significant reductions in CK and LDH levels and muscle soreness compared with the placebo [p<0.05], although no significant differences were observed between the two supplements [p>0.05]. It is concluded that dietary supplementation with carbohydrate and whey protein at a ratio of 13 or 14 can bring about a reduction in muscle damage indices after eccentric resistance exercise. The optimum ratio, however, to be used in sports drinks and for recommendation to individuals starting exercise warrants further research