Reliability and validity of 2D-video analysis to objectively assess hamstring performance during the H-test

The H-test is commonly used during return-to-sport decisions after hamstring muscle injury. The primary aim was to evaluate the reliability of two-dimensional (2D) video analysis for the H-Test. The second aim was to assess its validity compared to an electronic gyroscope (gold standard), and the third aim was to establish normative values. We conducted a cross-sectional study including 30 healthy individuals. Mean, maximal velocities (V_Mean and V_max) and range of motion (ROM) of hip flexion were captured during the H-test to evaluate inter-rater and test-retest reliability using intraclass correlation coefficient (ICC_2,1) and standard error of measurement (SEM). Correlation analysis (r) and as typical error of estimate (TEE) were used to assess the validity between the video and the gyroscope. Reliability was excellent for ROM (ICC:0.91, [95% CI:0.83-0.95]), moderate for V_Mean (ICC:0.57; [95% CI:0.32-0.74]) and V_Max (ICC:0.64, [95% CI:0.43-0.79]). Strong positive correlations were found between video and gyroscope for V_Mean (r = 0.79, [95% CI:0.71-0.86]) and V_Max (r = 0.84, [95% CI:0.77-0.89]) and very strong for ROM (r = 0.89, [95% CI:0.85-0.93]). Males exhibited a higher V_Max (p < 0.001) than females, while females had a higher ROM (p < 0.001). 2D-video analysis is a valid and reliable method to assess ROM during the H-Test and could easily be implemented in clinical practice.