ADAPTATIONS TO 6 MONTHS OF AEROBIC SWIM TRAINING - CHANGES IN VELOCITY, STROKE RATE, STROKE LENGTH AND BLOOD LACTATE

The purpose of this investigation was to determine how swimming veloci ty (SV), stroke rate (SR), stroke length (SL) and blood lactate concen tration change as adaptations to six months of aerobic swim training. Subjects were trained male college swimmers (n = 8). Measurements were obtained following specially designed 400 m freestyle swim tests, pre - and post-intervention. The swim test consisted of 4 x 400 m freestyl e over two days. On day 1, subjects performed a maximal effort 400 m f reestyle swimming trial; maximal mean velocity (Vmax) for each swimmer was calculated from this effort. On the next day, subjects were instr ucted to perform three 400 m freestyle swims at constant velocities eq ual to 85 % 90 % and 95 % of Vmax, respectively Subjects rested one ho ur between swims. During each 400 m trial, lap time and time to comple te 10 mid-pool strokes (50 m) were measured to determine SV (m - s-1), SR (stroke - min-1) and SL (m . stroke-1). Mixed arterial blood sampl es were taken at the end of each 400 m trial to evaluate blood lactate concentration. Results indicated that post-maximal swimming velocity (Vpostmax) increased significantly from pre-intervention measures (p<0 .05). Blood lactate concentration decreased significantly relative.to SV and absolute lactate concentration following Vpostmax was significa ntly lower than that at Vpremax (p<0.05). Six of seven subjects increa sed Vmax due to increases in SL. Mean SL during the second test was si gnificantly higher (p<0.05). Also, during the 400 m maximal test, SL i ncreased significantly after sixth lap (p<0.05). There was no signific ant difference between SRs. The results of this study suggest that swi mming performance improvements as a result of aerobic training are due to increases in SL rather than SR.