The Effect of Exercise Compliance on Risk Reduction for Hamstring Strain Injury: A Systematic Review and Meta-Analyses.

Eccentric strength training can reduce the risk of hamstring strain injury (HSI) occurrence; however, its implementation can be impacted by athlete compliance and prescription. The aim of this review was to investigate the effects of intervention compliance, consistency and modality, on the prevention of HSIs among athletes. A literature search was conducted. 868 studies were identified prior to the application of the exclusion criteria which resulted in 13 studies identified. Random effects models were used to produce log odds ratios and 95% confidence intervals. Very high (>75.1%), moderate-high (50.1-75%), low-moderate (25.1-50%) and very low (<25%) and <1-, 1.01-3.00-, >3.01-weeks/session were used as thresholds of compliance and consistency, respectively. Modality was also observed. A positive effect on HSI incidence -0.61 (-1.05 to -0.17), favoring the intervention treatments (Z = -2.70, p = 0.007). There were non-significant, large differences between compliance (p = 0.203, Z = -1.272) and consistency (p = 0.137, Z = -1.488), with increased compliance and consistency showing greater effectiveness. A significant difference between intervention modalities was observed (p < 0.001, Z = -4.136), with eccentric interventions being superiorly effective. Compliance of >50.1% and consistent application with <3 weeks/session having positive effects on HSI incidence. Training interventions that can achieve high levels of compliance, and can be consistently performed, should be the objective of future practice.