The Protective Effect of Preseason Running Workload Against In-Season Hamstring Strain Injuries in Elite Soccer Players.

BACKGROUND: Preseason training plays a pivotal role in preparing athletes for the competitive season and reducing the risk of hamstring strain injuries (HSI). This study evaluated the protective effect of preseason running workload on the risk of in-season HSI in elite soccer players. HYPOTHESIS: Higher preseason sprint-related metric is associated with reduced risk of in-season HSI in elite soccer players. STUDY DESIGN: Cohort study. LEVEL OF EVIDENCE: Level 3. METHODS: Global positioning system data and HSI records from 67 elite Japanese soccer players between 2021 and 2023 were analyzed. Variables included internal workload, total distance, high-speed distance, sprint distance, sprint count, and acceleration/deceleration count. Multivariable logistic regression analysis determined the association between workload metrics and HSI risk. RESULTS: A total of 17 HSI incidents were recorded during the study period. Increased preseason sprint distance was associated significantly with a reduced risk of in-season HSI (odds ratio [OR], 0.896; 95% CI, 0.822-0.976; P = 0.01), even after adjustment (model 1: OR, 0.892; 95% CI, 0.814-0.979; P = 0.02, model 2: OR, 0.899; 95% CI, 0.822-0.983; P = 0.02). Higher sprint count was associated with decreased HSI risk (OR, 0.761; 95% CI, 0.633-0.916; P = 0.004), with consistent findings after adjustments (model 1: OR, 0.755; 95% CI, 0.623-0.916; P = 0.004, model 2: OR, 0.763; 95% CI, 0.631-0.923; P = 0.005). The area under the curve values for sprint distance and sprint count were 0.721 and 0.739, respectively. CONCLUSION: Preseason training marked by higher sprint distances and counts demonstrates a protective effect against in-season HSI in elite soccer players, supporting comprehensive preseason running workload as an essential strategy for reducing injury risk and enhancing season readiness. CLINICAL RELEVANCE: Incorporating sprint-focused training during the preseason may reduce HSI incidence and minimize injury-related absences in elite soccer players.