Does Lower Extremity ROM Asymmetry Or Previous Injury Predict Weight Shift During The FMS Squat?

Abstract

The Functional Movement Screen (FMS) Deep Squat Test (DS) assesses bilateral mobility of the ankle, knee and hip through a movement pattern that is intended to be performed with bilateral symmetry. Past history of lower extremity (LE) injury may influence LE joint range of motion (ROM). Previous studies have examined the influence of LE ROM on squat depth, but not its influence on lateral weight shift (LWS). PURPOSE: The purpose of this study was to determine if bilateral asymmetry in ankle, knee, and hip ROM or previous history of LE injury predicts LWS during the FMS DS. METHODS: Thirty-seven physically active subjects (19 F, 18 M, 20.8 ± 1.4 yrs) completed this IRB approved study. All subjects granted informed consent and completed a health history questionnaire including history of LE orthopedic injury. Subjects’ hip flexion (HF), knee flexion (KF), and ankle dorsiflexion (DF) ROM were measured with a goniometer using standard methodologies. A loaded lunge (LL) measurement was also taken to determine peak closed chain dorsiflexion. ROM asymmetry was calculated for each measurement. Participants then completed three trials of the FMS DS on 2 force plates (1200 Hz) and a Matlab script processed vertical ground reaction force (vGRF) data with a lowpass filter and computed limb symmetry index during the descent phase and full squat position. Multiple regression models were computed for both the descent phase and the full squat position of the DS to determine if ankle, knee, and hip ROM asymmetry, LL asymmetry, and LE injury history are predictors of LWS during the DS. RESULTS: Mean ROM asymmetries for HF (-0.09% ± 3.37), KF (0.24% ± 1.8), DF (-5.30% ± 43.28) and LL (5.14% ± 8.93) were calculated. The overall regression model for the descent phase was not significant, (F(5, 31) = 0.47, p = 0.796, r2 = 0.07) for the prediction of LWS. Additionally, the overall regression model for the full squat position was also not significant (F(5, 31) = 1.67, p = 0.17, r2 = 0.21) for the prediction of LWS. CONCLUSION: Asymmetry in HF, KF, and DF ROM along with LL asymmetry and previous history of LE injury do not predict LWS during FMS DS performance. Further investigation is needed to identify the causes of asymmetric DS performance to aid clinicians in corrective exercise prescription.