Injury prevention programs that include plyometric exercises reduce the incidence of anterior cruciate ligament injury: a systematic review of cluster randomised trials

QUESTION: Do injury prevention programs that include plyometric exercises reduce the incidence of anterior cruciate ligament (ACL) injuries in sport? DESIGN: Systematic review of (cluster) randomised trials with meta-analysis. PARTICIPANTS: Sporting participants of any age, sex or competition level. INTERVENTIONS: The experimental intervention was an injury prevention program that included plyometric exercises. The control intervention was the usual warm-up program, which did not include plyometric exercises. OUTCOME MEASURES: Exposure-based ACL injury rates. RESULTS: The initial search yielded 7,302 articles, of which nine met the inclusion criteria. All nine articles reported cluster randomised trials, providing data on 14,394 participants. The pooled results showed that injury prevention programs that include plyometric exercises reduce the risk of ACL injury by 60% per 1,000 hours of exposure compared with the control group, with an injury risk ratio (IRR) of 0.40 (95% CI 0.26 to 0.63). Data from subgroups of these trials estimated that this preventative effect may be stronger in males (IRR 0.21, 95% CI 0.07 to 0.62) and weaker in females (IRR 0.51, 95% CI 0.30 to 0.87), albeit with less precise estimates. Subgroup analysis also suggested a stronger effect on non-contact ACL injuries (IRR 0.34, 95% CI 0.18 to 0.65), whereas the effect on contact ACL injuries remained uncertain (IRR 0.59, 95% CI 0.15 to 2.30). CONCLUSIONS: Injury prevention programs that incorporate plyometric exercises substantially decrease the risk of ACL injuries more than warm-up programs that do not include plyometric exercises. The preventive effect appears to be stronger among males and in the prevention of ACL injuries that do not involve contact with another player. PROSPERO CRD42020196982.