Changes in sprint performance and sagittal plane kinematics after heavy resisted sprint training in professional soccer players
Sprint performance is an essential skill to target within soccer. However, time-consuming intervention models could be easily rejected by coaches. Therefore, alternative and efficient field training options are warranted. One such method could be heavy resisted sprint training. However, it is unknown whether such overload will be efficient in assisting increases in sprint performance in a professional setting, and whether violating kinematic specificity via heavy loading will lead to changes in unloaded sprinting kinematics. Thus, we investigated whether heavy resisted training affects sprint performance and sagittal plane kinematics. Training-induced changes in sprint FV-profiles were computed before and after the 9-week, 2 sessions x week protocol. Out of the two recruited teams (N = 32, age: 24.1 ± 5.0 years: height: 180 ± 10 cm; body-mass: 76.7 ± 7.7 kg), one was used as a control group continuing training as normal (CON, N = 13), while the experimental team was divided into two subgroups based on their initial sprint performance: 1) Heavy sled training with the 60% velocity drop (N = 10) and 2) 50% velocity drop load (N = 9). Both experimental groups improved significantly all 0-30-m split times (p < 0.05, d = -0.62 – -1.25), with post-hoc showing HS50% improving significantly compared to CON in 0-10-m split (d = 1.03) and Pmax (d = 1.16). No differences in sprinting kinematics were observed. With appropriate coaching, heavy sled training could be a pragmatic option to assist improvements in sprint performance without adverse changes in sprinting kinematics in professional soccer players.