Effect of a novel movement strategy in decreasing ACL risk factors in female adolescent soccer players: a randomized controlled trial.

OBJECTIVE: To determine the effect of a novel movement strategy incorporated within a soccer warm-up on biomechanical risk factors for anterior cruciate ligament injury during 3 sport-specific movement tasks. DESIGN: Single-blind, randomized controlled clinical trial. SETTING: Laboratory setting. PARTICIPANTS: Twenty top-tier female teenage soccer players. INTERVENTIONS: Subjects were randomized to the Core Position and Control movement strategy (Core-PAC) warm-up or standard warm-up, which took place before their regular soccer practice over a 6-week period. The Core-PAC focuses on getting the centre of mass closer to the plant foot or base of support. MAIN OUTCOME MEASURES: Peak knee flexion angle and abduction moments during a side-hop (SH), side-cut, and unanticipated side-cut task after the 6 weeks with (intervention group only) and without a reminder to use the Core-PAC strategy. RESULTS: The Core-PAC group increased peak flexion angles during the SH task [mean difference = 6.2 degrees; 95% confidence interval (CI), 1.9-10.5 degrees; effect size = 1.01; P = 0.034] after the 6-week warm-up program without a reminder. In addition, the Core-PAC group demonstrated increased knee flexion angles for the side-cut (mean difference = 8.5 degrees; 95% CI, 4.8-12.2 degrees; ES = 2.02; P = 0.001) and SH (mean difference = 10.0 degrees; 95% CI, 5.7-14.3 degrees; ES = 1.66; P = 0.001) task after a reminder. No changes in abduction moments were found. CONCLUSIONS: The results of this study suggest that the Core-PAC may be one method of modifying high-risk soccer-specific movements and can be implemented within a practical, team-based soccer warm-up. The results should be interpreted with caution because of the small sample size.

The effect of a novel movement strategy in decreasing ACL risk factors in female adolescent soccer players.

There is a need to investigate the effect of specific movement strategies in reducing biomechanical risk factors for anterior cruciate ligament injury in young female athletes. The purpose of this study was (a) to determine the feasibility of implementing a novel movement strategy (Core-PAC) into a team warm-up before soccer training based on subject compliance and integration of the Core-PAC into the warm-up and (b) to determine whether the Core-PAC would improve peak knee flexion angles and peak abduction moments at the knee during a side cut (SC) and an unanticipated side cut (USC) before kicking a soccer ball, and a side hop (SH) task after immediate instruction and after a 4-week training program. A convenience sample of ten 14- to 16-year-old female soccer players were instructed in the Core-PAC immediately after baseline testing and during a training program consisting of a 20-minute warm-up, 2 times per week. The Core-PAC was understood and accepted by the subjects and incorporated into their warm-up activities with good compliance. After the immediate instruction, there were significant increases in peak knee flexion angles of a mean 6.4° during the SC (p = 0.001), 3.5° during the USC (p = 0.007), and 5.8° during the SH (p < 0.001) tasks. Peak knee abduction moments decreased by a mean of 0.25 N·m·kg(-1) during the SC (p < 0.03), 0.17 N·m·kg(-1) during the USC (p = 0.05), and 0.27 N·m·kg(-1) during the SH (p = 0.04) tasks. After the 4-week training program, some individuals showed improvement. The results of this study suggest that the Core-PAC may be 1 method of modifying high-risk movements for ACL injury such as side cutting and single-leg landing.

Reliability and validity of observational risk screening in evaluating dynamic knee valgus.

STUDY DESIGN: Nonexperimental methodological study. OBJECTIVES: To determine the interrater and intrarater reliability and validity of using observational risk-screening guidelines to evaluate dynamic knee valgus. BACKGROUND: A deficiency in the neuromuscular control of the hip has been identified as a key risk factor for noncontact anterior cruciate ligament (ACL) injury in postpubescent females. This deficiency can manifest itself as a valgus knee alignment during tasks involving hip and knee flexion. There are currently no scientifically tested methods to screen for dynamic knee valgus in the clinic or on the field. METHODS: Three physiotherapists used observational risk-screening guidelines to rate 40 adolescent female soccer players according to their risk of ACL injury. The rating was based on the amount of dynamic knee valgus observed on a drop-jump landing. Ratings were evaluated for intrarater and interrater agreement using kappa coefficients. Sensitivity and specificity of ratings were evaluated by comparing observational ratings, with measurements obtained using 3-dimensional (3-D) motion analysis. RESULTS: Kappa coefficients for intrarater and interrater agreement ranged from 0.75 to 0.85, indicating that ratings were reasonably consistent over time and between physiotherapists. Sensitivity values were inadequate, ranging from 67% to 87%. This indicated that raters failed to detect up to a third of "truly high-risk" individuals. Specificity values ranged from 60% to 72%, which was considered adequate for the purposes of the screening. CONCLUSION: Observational risk screening is a practical and cost-effective method of screening for ACL injury risk. Rater agreement and specificity were acceptable for this method, but sensitivity was not. To detect a greater proportion of individuals at risk of ACL injury, coaches and clinicians should ensure that they include additional tests for other high-risk characteristics in their screening protocols.