Abstract

The purpose of this study was to investigate whether drop jump warm-up (DW) protocols with varying loads (0%, 5%, and 10% body weight) are effective in enhancing swim start performance compared to a conventional warm-up (CW) routine for youth swimmers. A total of 23 middle and high school swimmers (age: 16.61 ± 1.64 years, height: 1.73 ± 0.07 m, weight: 64.87 ± 8.82 kg, athletic experience: 7.04 ± 2.65 years) participated in this study. They completed swim start trials after both their CW and DW, respectively, in randomized order. Kinematic variables, including entry and take-off angle, horizontal flight distance and velocity, and starting time, were analyzed using high-speed camera motion data. In addition, an inertial measurement unit was used to measure underwater pelvic motion during dolphin kicking, including the main frequency of pelvic angular velocity. The CW resulted in faster underwater speeds and shorter total start times compared to the DW. Furthermore, during underwater dolphin kicking, the main frequency of pelvic angular velocity in the medio-lateral axis following the CW was higher than after the DW. However, the only variable that improved with the DW was the take-off horizontal distance, which was longer than with the CW. No significant differences were found between drop jump conditions (i.e., 0%, 5%, and 10% extra body weight). Conclusively, CW routines appear to be more effective, and DW did not yield performance improvements regardless of the load applied, except for take-off horizontal distance in adolescent swimmers. Future studies should consider other warm-up protocols that account for individual characteristics and the biomechanical validity of underwater dolphin kicking movements.