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J Athl Train. 2011 Jan-Feb;46(1):5-10. doi: 10.4085/1062-6050-46.1.5.

Ankle-dorsiflexion range of motion and landing biomechanics.

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  • 1Athletic Training Services, Boston University, MA, USA.

Abstract

CONTEXT:

A smaller amount of ankle-dorsiflexion displacement during landing is associated with less knee-flexion displacement and greater ground reaction forces, and greater ground reaction forces are associated with greater knee-valgus displacement. Additionally, restricted dorsiflexion range of motion (ROM) is associated with greater knee-valgus displacement during landing and squatting tasks. Because large ground reaction forces and valgus displacement and limited knee-flexion displacement during landing are anterior cruciate ligament (ACL) injury risk factors, dorsiflexion ROM restrictions may be associated with a greater risk of ACL injury. However, it is unclear whether clinical measures of dorsiflexion ROM are associated with landing biomechanics.

OBJECTIVE:

To evaluate relationships between dorsiflexion ROM and landing biomechanics.

DESIGN:

Descriptive laboratory study.

SETTING:

Research laboratory.

PATIENTS OR OTHER PARTICIPANTS:

Thirty-five healthy, physically active volunteers.

INTERVENTION(S):

Passive dorsiflexion ROM was assessed under extended-knee and flexed-knee conditions. Landing biomechanics were assessed via an optical motion-capture system interfaced with a force plate.

MAIN OUTCOME MEASURE(S):

Dorsiflexion ROM was measured in degrees using goniometry. Knee-flexion and knee-valgus displacements and vertical and posterior ground reaction forces were calculated during the landing task. Simple correlations were used to evaluate relationships between dorsiflexion ROM and each biomechanical variable.

RESULTS:

Significant correlations were noted between extended-knee dorsiflexion ROM and knee-flexion displacement (r  =  0.464, P  =  .029) and vertical (r  =  -0.411, P  =  .014) and posterior (r  =  -0.412, P  =  .014) ground reaction forces. All correlations for flexed-knee dorsiflexion ROM and knee-valgus displacement were nonsignificant.

CONCLUSIONS:

Greater dorsiflexion ROM was associated with greater knee-flexion displacement and smaller ground reaction forces during landing, thus inducing a landing posture consistent with reduced ACL injury risk and limiting the forces the lower extremity must absorb. These findings suggest that clinical techniques to increase plantar-flexor extensibility and dorsiflexion ROM may be important additions to ACL injury-prevention programs.

PMID:
21214345
[PubMed - indexed for MEDLINE]
PMCID:
PMC3017488
Free PMC Article
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