Proximal core strengthening training for anterior cruciate ligament injury prevention with biomechanical improvements in knee/hip kinematics and strength gains: a systematic review and meta-analysis of low-certainty evidence.

OBJECTIVES

This study evaluated the effects of proximal core training on biomechanical risk factors and strength parameters in individuals at high risk of anterior cruciate ligament (ACL) injury (specifically: those exhibiting pathological movement patterns, neuromuscular deficits or biomechanical risk factors) and compared direct versus indirect interventions. We hypothesised that targeted training enhances dynamic knee stabilisation and hip control during high-risk manoeuvres, with direct approaches providing superior biomechanical benefits through neuromuscular control optimisation.

DESIGN

Systematic review and meta-analysis using the Grading of Recommendation, Assessment, Development and Evaluation (GRADE) approach.

DATA SOURCES

We searched (PubMed, Web of Science, EBSCO Academic Search Premier (ASP)+Business Source Premier (BSP)) for relevant literature published between its inception and the date of retrieval (22 April 2024).

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

This study included studies comparing the effects of proximal core intensification training and lower extremity training, evaluated their influences on biomechanical risk factors and strength parameters in three types of high-risk ACL populations, and compared the direct and indirect intervention effects. The three types of people include: (1) athletes with pathological exercise patterns, (2) those with neuromuscular defects after ACL injury/reconstruction and (3) those without injury but with biomechanical risk factors.

DATA EXTRACTION AND SYNTHESIS

Two independent reviewers used standardised methods to search, screen and code included studies. Risk of bias was assessed using the Cochrane Collaboration and Evidence Project tools. A meta-analysis was conducted using random effects models. Findings were summarised in GRADE evidence profiles and synthesised qualitatively.

RESULTS

24 studies with a total of 749 participants were included. Meta-analyses demonstrated that proximal core strengthening training may increase lower extremity muscle strength (quadriceps peak torque: standardised mean differences (SMD)=0.65, 95% CI (0.29 to 1.01), I²=0%; hamstring peak torque: SMD=0.53, 95% CI (0.14 to 0.92), I²=0%; both p<0.05, low-quality evidence). For movement kinematics, task-dependent improvements were observed: peak knee flexion angle likely increased during jumping (SMD=0.58, 95% CI (0.20 to 0.96), I²=32%) and single-leg squatting (SMD=0.60, 95% CI (0.07 to 1.26), I²=0%) (both p≤0.05, low-quality evidence) but may have little meaningful effect during walking (low-quality evidence). Peak hip flexion may substantially increase during jumping (SMD=0.83, 95% CI (0.19 to 1.47), I²=0%, p<0.05, low-quality evidence), while core endurance may improve (plank time: SMD=0.63, 95% CI (0.12 to 1.13), I²=0%, p<0.05, low-quality evidence).

CONCLUSIONS

Proximal core training has the potential to improve core endurance, knee kinematics and lower limb strength in individuals at high risk of ACL injury, but evidence remains limited to late postoperative and exercise studies. Standardised protocols and harm rate validation are needed to confirm the preventive effectiveness of multidimensional protocols.

PROSPERO REGISTRATION NUMBER

CRD42024532199.