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J Athl Train. 2012 Sep-Oct;47(5):525-36. doi: 10.4085/1062-6050-47.5.10.

Neuromuscular characteristics of individuals displaying excessive medial knee displacement.

Author information

1
University of North Carolina at Chapel Hill, Department of Exercise and Sport Science, 216 Fetzer Gym, CB#8700, Chapel Hill, NC, USA. dpadua@email.unc.edu

Abstract

CONTEXT:

Knee-valgus motion is a potential risk factor for certain lower extremity injuries, including anterior cruciate ligament injury and patellofemoral pain. Identifying neuromuscular characteristics associated with knee-valgus motion, such as hip and lower leg muscle activation, may improve our ability to prevent lower extremity injuries.

OBJECTIVE:

We hypothesized that hip and lower leg muscle-activation amplitude would differ among individuals displaying knee valgus (medial knee displacement) during a double-legged squat compared with those who did not display knee valgus. We further suggested that the use of a heel lift would alter lower leg muscle activation and frontal-plane knee motion in those demonstrating medial knee displacement.

DESIGN:

Descriptive laboratory study.

SETTING:

Research laboratory.

PATIENTS OR OTHER PARTICIPANTS:

A total of 37 healthy participants were assigned to the control (n = 19) or medial-knee-displacement (n = 18) group based on their double-legged squat performance.

MAIN OUTCOME MEASURE(S):

Muscle-activation amplitude for the gluteus maximus, gluteus medius, adductor magnus, medial and lateral gastrocnemius, and tibialis anterior was measured during 2 double-legged squat tasks. The first task consisted of performing a double-legged squat without a heel lift; the second consisted of performing a double-legged squat task with a 2-in (5.08-cm) lift under the heels.

RESULTS:

Muscle-activation amplitude for the hip adductor, gastrocnemius, and tibialis anterior was greater in those who displayed knee valgus than in those who did not (P < .05). Also, use of heel lifts resulted in decreased activation of the gluteus maximus, hip adductor, gastrocnemius, and tibialis anterior muscles (P < .05). Use of heel lifts also eliminated medially directed frontal-plane knee motion in those displaying medial knee displacement.

CONCLUSIONS:

Medial knee displacement during squatting tasks appears to be associated with increased hip-adductor activation and increased co-activation of the gastrocnemius and tibialis anterior muscles.

PMID:
23068590
PMCID:
PMC3465033
DOI:
10.4085/1062-6050-47.5.10
[Indexed for MEDLINE]
Free PMC Article

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