Kinematic analysis of the underwater glide phase during the push-off in competitive swimmers.

The aim of the study was to analyze the kinematic parameters of the push-off start during the underwater glide in competitive swimmers. 74 swimmers participating in the Spanish Championships were filmed and analyzed by DLT-2D photogrammetry after the push-off start in crawl, backstroke and butterfly. Between genders there were differences in distance and speed. Male swimmers covered greater distances (1.37±0.06 vs 1.20±0.05 m, η2 = 0.02, F = 3.85, p = 0.05) and were faster (2.36±0.03 and 2.08±0.03 m/s, η2 = 0.14, F = 36.14, p<0.001) than female swimmers. Between strokes there were greater differences in time (η2 = 0.06, F = 6.76, p = 0.00) and distance (η2 = 0.38, F = 67.08, p< 0.001), than in speed (η2 = 0.05, F = 5.63, p< 0.001). During the backstroke, less time (0.50±0.04 s) and distance (1.01±0.07 m) were used, being the slowest style (2.12±0.04 m/s). In butterfly, less time (0.63±0.04 s) and distance (2.25±0.04 m) were used, while crawl was the fastest (2.30±0.04 m/s). These results allow us to characterize the underwater glide phase and provide useful data for both competitive swimmers and coaches to improve performance.