THE EFFECTS OF L-CARNITINE SUPPLEMENTATION ON PERFORMANCE DURING INTERVAL SWIMMING

To examine the effects of L-carnitine supplementation on short high-in tensity exercise, twenty male collegiate swimmers completed two trials separated by seven days. Each trial consisted of five 91.4 m (100 yd) swims with a two minute rest interval between each bout. Following th e first trial subjects were evenly and randomly assigned to either an L-carnitine (LC) group or a placebo (PL) group. The LC group ingested 2 grams L-carnitine in a citrus drink twice daily for 7 days, while th e PL group received only the citrus drink during the same time period. Performance times were recorded for each repeat during both trials. B lood samples (5 ml) were obtained from an antecubital vein 1 minute fo llowing the interval set. Blood pH, base excess (BE), lactate (LA), ca rnitine and carnitine fractions were measured. Total serum carnitine w as significantly (p<0.05) elevated (75.9 +/- 2.0 vs. 106.4 +/- 3.5 mu mol.1(-1)) in the LC group following treatment, while the PL group was unchanged (79.5 +/- 2.8 vs. 77.6 +/- 5.3 mu mol.1(-1)). Free and shor t-chain serum carnitine fractions were also increased (p<0.05) in the LC group, but were not altered in the PL group. No differences in perf ormance times were observed between trials or between groups. Blood pH , LA and BE revealed a similar response in both groups during each tri al. Despite the elevation in serum L-carnitine and carnitine fractions , these results indicate that L-carnitine supplementation does not pro vide an ergogenic benefit during repeated bouts of high-intensity anae robic exercise in highly trained swimmers.