Effects of branched-chain amino acid supplementation on serum creatine kinase and lactate dehydrogenase after prolonged exercise

Background, The aim of this study was to examine the effects of branched-ch ain amino acid (BCAA) supplementation on serum indicators of muscle damage after prolonged exercise. We hypothesized that BCAA supplementation would r educe the serum activities of intramuscular enzymes associated with muscle damage. Methods. To test this hypothesis, sixteen male subjects were assigned to on e of two groups: the supplemental group (consuming 12 g.d(-1) BCAA for 14 d in addition to their normal diet) or the control group (normal diet only). Baseline serum creatine kinase (CE;) and lactate dehydrogenase (LDH), show n to be accurate indicators of muscle damage, were determined during the we ek before the exercise test. The exercise test was administered on day seve n and required the subjects to cycle for 120 min on an ergometer at approxi mately 70 % (V) over dot O-2max. Blood samples were taken prior to and imme diately following exercise and at 1 hr, 2 hrs, 3 hrs, 4 hrs, 1 d, 3 d, 5 d and 7 d postexercise. All subjects were required have their diets analyzed daily during the 14 d. Results. Dietary analyses indicated that all subjects consumed the recommen ded daily intake of BCAA (0.64 g.kg(-1)) in their normal diets. Baseline se rum values for CK and LDH were not different between groups in the 7 d prio r to the test (p>0.05). However there were significant increases (p<0.05) b etween the pre-exercise and postexercise values for LDH and CK until 5 d po stexercise test. Importantly; the BCAA supplementation significantly reduce d this change in LDH from 2hrs to 5 d posttest, and CK from 4 hrs to 5 d po st-test (p<0.05). Conclusions. These results indicate that supplementary BCAA decreased serum concentrations of the intramuscular enzymes CK and LDH following prolonged exercise, even when the recommended intake of BCAA was being consumed. Thi s observation suggests that BCAA supplementation may reduce the muscle dama ge associated with endurance exercise.