Acute Changes in Hamstring Injury Risk Factors After a Session of High-Volume Maximal Sprinting Speed Efforts in Soccer Players.

Background: Maximal sprinting speed (MSS) overexposure is associated with increased risk of injury. This study aimed to describe changes in sprint performance-related factors and hamstring strain injury (HSI) risk factors after a high-volume sprinting session in soccer players.

Hypothesis: A high-volume sprinting session can induce acute changes in several sprint performance-related factors (sprint time and mechanical properties) and HSI risk factors (posterior chain muscle strength, hamstring range of motion, and dynamic lumbo-pelvic control [LPC], measured as changes in anterior pelvic tilt [APT] during maximal speed sprinting).

Study Design: Prospective observational case series.

Level Of Evidence: Level 4.

Methods: Fifteen active male amateur soccer players participated. Changes in sprint performance-related factors and HSI risk factors were examined for 72 hours after high-volume MSS efforts (H-VMSSE) using a soccer-contextualized multifactorial approach. Muscle damage proxy markers (hamstring perceived soreness and creatine kinase) were also examined.

Results: H-VMSSE induced decrements in sprint performance-related factors. Significant reductions in theoretical maximal horizontal velocity ( < 0.01; effect size [ES], -0.71) and performance ( = 0.02; ES, -0.59) were observed for 48 and 72 hours after H-VMSSE. Small but significant reductions in posterior chain muscle force-generating capacity were detected for 48 and 72 hours after H-VMSSE for the nondominant ( < 0.03; ES, -0.60) and dominant ( < 0.04; ES, -0.40) leg. Finally, players exhibited persistent small, albeit nonsignificant ( = 0.06; ES, 0.53), decreases in dynamic LPC (APT increases) for 72 hours after H-VMSSE.

Conclusion: H-VMSSE induced declines in both sprint performance-related factors and HSI risk factors. Sprinting can alter a player's anatomic structure by increasing APT during the maximum speed phase of the sprint.

Clinical Relevance: A soccer-contextualized multifactorial approach might allow for the regulation of MSS dosage depending on individual HSI risk factor status, thereby serving as a tailored "vaccine" for sprinting needs.