Prediction of Dynamic Postural Stability During Single-Leg Jump Landings by Ankle and Knee Flexibility and Strength

in Journal of Sport Rehabilitation
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Context:

Dynamic postural stability is important for injury prevention, but little is known about how lower-extremity musculoskeletal characteristics (range of motion [ROM] and strength) contribute to dynamic postural stability. Knowing which modifiable physical characteristics predict dynamic postural stability can help direct rehabilitation and injury-prevention programs.

Objective:

To determine if trunk, hip, knee, and ankle flexibility and strength variables are significant predictors of dynamic postural stability during single-leg jump landings.

Design:

Cross-sectional study.

Setting:

Laboratory.

Participants:

94 male soldiers (age 28.2 ± 6.2 y, height 176.5 ± 2.6 cm, weight 83.7 ± 26.0 kg).

Intervention:

None.

Main Outcome Measures:

Ankle-dorsiflexion and plantar-flexion ROM were assessed with a goniometer. Trunk, hip, knee, and ankle strength were assessed with an isokinetic dynamometer or handheld dynamometer. The Dynamic Postural Stability Index (DPSI) was used to quantify postural stability. Simple linear and backward stepwise-regression analyses were used to identify which physical characteristic variables were significant predictors of DPSI.

Results:

Simple linear-regression analysis revealed that individually, no variables were significant predictors of the DPSI. Stepwise backward-regression analysis revealed that ankle-dorsiflexion flexibility, ankle-inversion and -eversion strength, and knee-flexion and -extension strength were significant predictors of the DPSI (R2 = .19, P = .0016, adjusted R2 = .15).

Conclusion:

Ankle-dorsiflexion ROM, ankle-inversion and -eversion strength, and knee-flexion and -extension strength were identified as significant predictors of dynamic postural stability, explaining a small amount of the variance in the DPSI.

Williams and Nagai are with the Warrior Human Performance Research Laboratory, University of Pittsburgh, Pittsburgh, PA. Sell is with the Michael W. Krzyzewski Human Performance Laboratory, Department of Orthopedic Surgery, Duke University, Durham, NC. Abt and Lephart are with the College of Health Sciences, University of Kentucky, Lexington KY. Rowe is with the Carl R. Darnall Army Medical Center, Fort Hood, TX. McGrail is with the Office of the Surgeon General, Dept of the Army, Washington DC.

Address author correspondence to Timothy Sell at tcs30@duke.edu.