Evaluation of muscle damage after a rugby match with special reference to tackle plays

Objective: To investigate blood indices of muscle damage after a competitive rugby match. Methods: Fifteen elite amateur rugby players volunteered to participate (mean (SE) age 26.6 (0.7) years, height 179.8 (1.0) cm, weight 87.4 (2.2) kg, and VO(2)MAX 58.5 (1.2) ml/kg/min). The study was conducted after two competitive matches during the 1999-2000 season. Plasma concentrations of lactate, potassium (K+), sodium (Na+), and myoglobin, and the activity of creatine kinase were measured before and after the matches. In addition, the number of tackles by and on each subject and the average duration of the work and rest periods were analysed using video recordings of the matches. Results: Myoglobin concentration and creatine kinase activity showed appreciable transient increases after the match. Peak values for myoglobin concentration (980 (166) mu g/l) and creatine kinase activity (1081 ( 159) U/l) were observed 45 minutes and 24 hours after the match respectively. Positive and significant correlations were observed between the number of tackles and both peak myoglobin concentration (r = 0.85, p< 0.01; n = 14) and peak creatine kinase activity (r = 0.92, p< 0.01; n = 14). Plasma lactate and K+ concentrations also showed appreciable increases after the match, whereas plasma Na+ concentration showed a gradual decrease. The mean duration of the work and rest periods were 21.5 (2.2) and 24.3 (3.1) seconds respectively. Conclusions: The rugby matches resulted in serious structural damage to the muscles, the extent of which was highly dependent on the number of tackles.