Determination of the Criterion-Related Validity of Hip Joint Angle Test for Estimating Hamstring Flexibility Using a Contemporary Statistical Approach

Abstract

Objective: 

To examine the criterion-related validity of the horizontal hip joint angle (H-HJA) test and vertical hip joint angle (V-HJA) test for estimating hamstring flexibility measured through the passive straight-leg raise (PSLR) test using contemporary statistical measures.

Design: 

Validity study.

Setting: 

Controlled laboratory environment.

Participants: 

One hundred thirty-eight professional trampoline gymnasts (61 women and 77 men).

Assessment of Risk Factors: 

Hamstring flexibility.

Main Outcome Measures: 

Each participant performed 2 trials of H-HJA, V-HJA, and PSLR tests in a randomized order. The criterion-related validity of H-HJA and V-HJA tests was measured through the estimation equation, typical error of the estimate (TE_EST), validity correlation (β), and their respective confidence limits.

Results: 

The findings from this study suggest that although H-HJA and V-HJA tests showed moderate to high validity scores for estimating hamstring flexibility (standardized TE_EST = 0.63; β = 0.80), the TE_EST statistic reported for both tests was not narrow enough for clinical purposes (H-HJA = 10.3 degrees; V-HJA = 9.5 degrees). Subsequently, the predicted likely thresholds for the true values that were generated were too wide (H-HJA = predicted value ± 13.2 degrees; V-HJA = predicted value ± 12.2 degrees).

Conclusions: 

The results suggest that although the HJA test showed moderate to high validity scores for estimating hamstring flexibility, the prediction intervals between the HJA and PSLR tests are not strong enough to suggest that clinicians and sport medicine practitioners should use the HJA and PSLR tests interchangeably as gold standard measurement tools to evaluate and detect short hamstring muscle flexibility.