Single leg squat performance in physically and non-physically active individuals: a cross-sectional study.

Area of Science:

• Biomechanics
• Sports Medicine
• Kinesiology

Background:

• Single-leg squat (SLS) is a functional test for lower limb assessment, typically rated visually by clinicians.
• Current clinical ratings are qualitative and lack objective kinematic and surface electromyography (sEMG) data.
• This study aimed to evaluate clinical rating agreement and identify predictors of good SLS performance.

Purpose of the Study:

• To determine the agreement among clinicians in rating single-leg squat (SLS) performance.
• To identify kinematic and sEMG predictors of successful SLS execution in physically active and non-physically active individuals.

Main Methods:

• Seventy-two healthy adults (physically active and non-physically active) performed three SLSs.
• Clinical ratings, kinematic data, and sEMG were collected.
• Six expert clinicians rated SLS videos; statistical analysis identified predictors.

Main Results:

• Intra-rater reliability for SLS ratings ranged from moderate to almost perfect.
• Inter-rater reliability was fair across different time points.
• Physically active individuals showed significantly greater knee and hip flexion during SLS compared to non-physically active individuals.
• Greater knee flexion was a significant predictor of good SLS performance.

Conclusions:

• Physically active individuals exhibit superior SLS performance with greater knee and hip flexion.
• Increased knee flexion is a reliable predictor of SLS quality and may serve as an injury-protective factor.
• Objective kinematic measures, like knee flexion, enhance the assessment of functional lower limb performance.