Abstract

Aim of the study was to determine how swimming velocity (SV), stroke rate (SR), stroke length (SL) and blood lactate concentration change as adaptations to 6 mo of aerobic swim training. Subjects were trained male college swimmers. Measurements were obtained following specially designed 400 m freestyle swim tests, pre- and post-intervention. The swim test consisted of 4x400 m freestyle over 2 d. On day 1, subjects performed a maximal effort 400 m freestyle swimming trial; maximal mean velocity (Vmax) for each swimmer was calculated. Next day, subjects performed 3 400-m-freestyle swims at constant velocities equal to 85, 90 and 95 of Vmax, respectively. Subjects rested 1 h between swims. During each 400 m trial, lap time and time to complete 10 mid-pool strokes (50 m) were measured to determine SV (m/s), SR (stroke/min) and SL (m/stroke). Blood samples 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. Blood lactate concentration decreased significantly relative to SV and absolute lactate concentration following Vpostmax was significantly lower than that at Vpremax. 6 of 7 subjects increased Vmax due to increases in SL. Mean SL during the second test was significantly higher. Also, during the 400 m maximal test, SL increased significantly after 6th lap. Result: swimming performance improvements after aerobic training are due to increases in SL rather than SR. Verf.-Referat