ACL tears end seasons and sometimes careers. They cost athletes an average of 9–12 months of rehabilitation. And a substantial proportion of them — particularly in female athletes and adolescents — are entirely preventable with the right neuromuscular training.
The evidence for prevention programmes is stronger than almost any other injury intervention in sports medicine. And it is still dramatically underused.
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The anterior cruciate ligament is most commonly torn during non-contact deceleration, cutting and landing tasks — not collisions. The mechanism is well characterised: valgus collapse (knee caving inward) combined with tibial internal rotation at or near full extension creates the impingement and rotational shear forces that exceed ACL tensile strength.
Hewett and colleagues (2005, American Journal of Sports Medicine) prospectively followed 205 female athletes across one season. Using 3D motion capture at baseline, they identified athletes who were ACL tear cases versus controls. The cases had shown significantly greater knee abduction moment, valgus angle and lateral trunk displacement during jump landing before their injury — establishing that biomechanical risk factors are measurable and precede injury.
The 4–6x higher ACL incidence in female athletes versus males is partially explained by hormonal factors (oestrogen receptors on ACL fibroblasts modulate collagen laxity, Hewett 2006), partially by biomechanical differences (wider pelvis angle of hip adduction), and substantially by training exposure — female athletes in many team sports receive significantly less neuromuscular training emphasis than their male counterparts.
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The most rigorously studied prevention programme is the PEP Programme (Prevent injury and Enhance Performance), developed by Mandelbaum and colleagues (2005). In a 1,435-player prospective RCT, ACL tear incidence in trained female soccer players fell by 88% in year one and 74% in year two compared to controls. The programme takes 20 minutes and consists of warm-up running, stretching, strengthening, plyometrics and agility work with specific technique cues.
Subsequent programmes — FIFA 11+, HarmoKnee, the Loughborough programme — have consistently demonstrated 50–60% injury rate reductions in prospective studies. The common elements across programmes:
- Hip abductor and external rotator strengthening (reduces dynamic valgus)
- Single-leg plyometric landing drills with knee-over-toe alignment cues
- Hamstring co-contraction training for anterior tibial translation restraint
- Deceleration and cutting mechanics with upright trunk cuing
- Minimum 2 sessions per week sustained across the season (one-off blocks do not protect)
Myer and colleagues (2011) identified that the knee abduction moment during landing — measurable via force plate — is the most predictive individual biomechanical risk factor. Athletes with valgus collapse moments above a threshold had a 6.8x higher prospective ACL tear risk. This suggests targeted screening during preseason is a rational investment for team sports with high ACL burden (basketball, football, handball, skiing).
Nordic hamstring curls reduce hamstring-to-quadriceps ratio imbalance, which is a secondary ACL risk factor — the quadriceps pulls the tibia anteriorly at low knee flexion angles, and hamstring co-contraction restrains this force.
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The strength qualities underpinning ACL prevention — eccentric hip and knee control, hamstring to quadriceps ratio, single-leg landing force absorption — all develop progressively over months and years of structured loading. Tracking these strength gains systematically across training cycles allows practitioners to confirm adaptation is occurring at the right rate. For coaches monitoring maximal strength and estimating safe loading progressions for athletes in prevention training programmes, the free tool at winsport.uk/tools/strength/one-rep-max-calculator estimates 1RM from submaximal efforts, giving a strength tracking anchor for squats, deadlifts and single-leg variations used in ACL prevention protocols.
Is ACL prevention training a mandatory part of preseason preparation in the sports programme you work with?