Effects of Time of Day on Race Splits, Kinematics, and Blood Lactate During a 50-m Front Crawl Performance

• Published in: Journal of strength and conditioning research 2021-03, Vol.35 (3), p.819-825
• Main Authors: Lisbôa, Felipe D., Raimundo, João A.G., Pereira, Gustavo S., Ribeiro, Guilherme, de Aguiar, Rafael A., Caputo, Fabrizio
• Format: Article
• Language: English
• Subjects: Biomechanical Phenomena; Humans; Lactates; Male; Swimming; Warm-Up Exercise
• ISSN: 1064-8011; 1533-4287
• DOI: 10.1519/JSC.0000000000002794

ABSTRACTLisbôa, FD, Raimundo, JAG, Pereira, GS, Ribeiro, G, de Aguiar, RA, and Caputo, F. Effects of time of day on race splits, kinematics, and blood lactate during a 50-m front crawl performance. J Strength Cond Res XX(X)000–000, 2018—This study aimed to investigate the performance, race splits, metabolic, and stroke parameters during 2 successive 50-m front crawl under conditions simulating a competition. Eleven competitive male swimmers (20 ± 3 years, 182 ± 5 cm, and 77 ± 5 kg) performed 2 successive 50-m front crawl trials in a 50-m swimming pool at 10 AM and 5 PM. Block time (tB), 15-m performance (t.15-m), and 50-m performance (t.50-m) were measured. Velocity (V), stroke rate (SR), stroke length (SL), and stroke index (SI) were measured at 3 time points during the trials. Pre-trial and post-trial blood samples were taken to determine blood lactate accumulation (Δ[Lac]). For t.50-m, the relative difference between 10 AM and 5 PM reached 0.1% (p = 0.7; effect size [ES] = 0.02). Furthermore, no differences in tB (p = 0.12; ES = −0.28) and t.15-m (p = 0.39; ES = −0.16) were observed between periods. Both V (p = 0.11; ES = −0.14) and SI (p = 0.16; ES = 0.15) were also similar. Higher values of SR were recorded at 10 AM (p = 0.03; ES = −0.32), whereas the morning values of SL were lower (p = 0.04; ES = 0.3). Δ[Lac] was not significantly different between periods (p = 0.07; ES = −0.27). Although time of the day did not impact performance in 2 successive 50-m front crawl performances, different stroke parameters profiles were observed during these trials. This may help coaches design specific warm-up exercises to enhance performance at different times of the day.