Association Between Isometric Hip Muscle Strength and Y-Balance Test Performance in Healthy Adults.

Area of Science:

• Biomechanics and Motor Control
• Sports Medicine and Exercise Science

Background:

• Dynamic balance is crucial for lower extremity function and relies on coordinated muscle action.
• Hip muscle strength is recognized as important for Y-Balance Test (YBT) performance, but specific contributions are unclear.

Purpose of the Study:

• To investigate the associations between isometric hip abduction, external rotation, and extension strength and YBT performance in healthy adults.
• To determine the relative contributions of individual hip muscle groups to dynamic balance as measured by the YBT.

Main Methods:

• Cross-sectional study involving 104 healthy adults.
• Isometric hip strength (abduction, external rotation, extension) measured using handheld dynamometry and normalized to joint torque (Nm/kg).
• Y-Balance Test (YBT) assessed in anterior, posteromedial, and posterolateral directions; linear mixed models used to analyze associations, controlling for sex, age, and BMI.

Main Results:

• All hip strength measures positively correlated with YBT performance; hip extension strength showed the strongest link to posterolateral reach.
• Sex was the strongest predictor of YBT performance, with males scoring higher than females across all directions.
• Hip extension and abduction strength independently predicted posterolateral reach, but not anterior reach or composite score, after covariate adjustment.

Conclusions:

• Sex is the primary determinant of YBT performance in healthy adults.
• Hip extension and abduction strength are specifically associated with posterolateral dynamic balance.
• The relationship between hip muscle strength and dynamic balance is direction-specific and influenced by sex.