Swimming turns reduce energy demands of the aerobic performance in front crawl

Purpose Performances in short-course (SC, 25 m) are typically faster than in long-course (LC, 50 m), largely due to the greater number of turns, but the specific energetic contribution of turns has not yet been quantified. This study tested the hypothesis that turns reduce the overall energy cost (C) in swimming, providing an energetic advantage in SC over LC. Methods Eleven male swimmers completed two randomized sessions in SC and LC pools, each consisting of five 400-m front crawl trials at submaximal intensity (70-86% of race velocity) paced by an underwater light system. Turn and clean swimming velocities were standardized between conditions to isolate the effect of turn number. Oxygen uptake, blood lactate, heart rate, perceived exertion, and stroke frequency were assessed, and metabolic power, total energy expenditure (E-tot), and C (E-tot/distance) were calculated. Results When analyzed at equivalent intensity (e.g. in trials corresponding to the same % of race velocity) mean velocity was higher in SC than LC across all intensities (+ 0.07 +/- 0.003 ms(-)(1), + 5.2%) while kinematic, physiological, and energetic parameters showed no significant differences (p > 0.05). When analyzed at paired (absolute) speeds, C values were about 4% higher il LC than in SC, indicating that swimming in short course is more economical, as hypothesized. Conclusions Turns reduce the overall energy cost of 400-m front crawl performance enabling swimmers to sustain higher mean velocities in SC. This highlights the importance of considering pool length when evaluating performance and prescribing training intensities.