Abstract / Summary
Abstract Despite the high prevalence and recurrence of acute hamstring strain injuries in athletes, the optimal rehabilitation strategy balancing rapid time to return to play (TTRTP) with durable re-injury protection remains unclear. We searched PubMed, Cochrane Library, Web of Science, Scopus, Embase, and Google Scholar from inception to January 2026 for English-language randomized controlled trials (RCTs) evaluating exercise-based rehabilitation, adjunctive biological modalities, or other approaches for acute hamstring strains in athletes. TTRTP was the primary outcome; re-injury rate was secondary. Certainty was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE). Models were selected based on heterogeneity and clinical plausibility of pooling. 14 RCTs (693 athletes) were included. A lengthening-focused exercise protocol (L-protocol) based on two trials may shorten TTRTP versus conventional rehabilitation (moderate certainty) without increasing re-injury risk (low certainty). Progressive agility and trunk stabilization (PATS) did not accelerate TTRTP (low certainty); the re-injury estimate was inconclusive (RD -0.35, 95% CI -0.74 to 0.03; I² = 72%; very low certainty; 2 trials), with the confidence interval including both a potential reduction and no effect. For adjunctive therapies, we analyzed Platelet-Rich Plasma (PRP) as a separate meta-analysis (three trials) and described radial extracorporeal shockwave therapy (rESWT) and low-level laser therapy (LLLT) as single-trial evidence. PRP showed heterogeneous effects (I² = 70%), rESWT modest benefit (one trial), and LLLT no added benefit (one trial). Pain-threshold rehab enhanced strength without delaying TTRTP (moderate certainty; one trial). Trial Sequential Analysis (TSA) indicated that the lengthening-focused exercise protocol (L-protocol) TTRTP benefit exceeded the monitoring boundary, suggesting sufficient evidence to rule out random error; however, this does not eliminate clinical heterogeneity or concerns about external validity. Lengthening-focused eccentric exercise may shorten TTRTP. Evidence for PATS and adjunctive modalities remains uncertain, warranting high-quality RCTs. Decisions should prioritize evidence certainty over statistical significance. Clinical trial registration: PROSPERO registration ID CRD420261387775.