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Table 2 Alternative H:Q ratios used by studies

From: Alternative Methods of Determining Hamstrings-to-Quadriceps Ratios: a Comprehensive Review

Alternative H:Q ratio Measurement Calculation
AST H:Q ratio Maximal concentric and eccentric hamstring and quadriceps strength are measured on an isokinetic dynamometer. Tested hamstring and quadriceps ROM are divided into several corresponding degree angles (e.g., 10, 20, 30...90° of knee flexion) or joint ranges (e.g., 0–10°, 10–20°, 20–30° of knee flexion). Hamstring and quadriceps concentric and eccentric AST are measured at each angle or by the PT of each joint range CR: Hamstring concentric AST ÷ quadriceps concentric AST
FR: Hamstring eccentric AST ÷ quadriceps concentric AST
RTD H:Q ratio Maximal and/or explosive hamstring and quadriceps isometric strength is measured on an isokinetic/custom built dynamometer. RTD is measured by the slope of the torque-time curve of specific time intervals from the force onset (e.g., 0–50, 0–100, 0–150 ms) Hamstrings RTD ÷ quadriceps RTD (at each time interval)
FI H:Q ratio Several maximal concentric hamstring and quadriceps strength repetitions (e.g., 30 and 50) are performed on an isokinetic dynamometer at a high angular velocity (e.g., 150°/s and 300°/s). FI can be calculated by different methods involving the difference between individual, PT or mean of the final and initial repetitions [e.g. (initial PT - final PT) ÷ initial PT × 100] Hamstring FI ÷ quadriceps FI
MS H:Q ratio Hamstring and quadriceps MS are measured by ACSA or MT obtained from MRI or ultrasound scans. The muscle average area values, the sum of MT or the volume by cubic spline interpolation of hamstrings and quadriceps muscles are calculated to determine MS H:Q ratio Hamstring MS ÷ quadriceps MS
MA H:Q ratio Maximal concentric quadriceps strength is measured on an isokinetic dynamometer. Hamstring and quadriceps muscles are fitted with EMG electrodes to measure MA during the test, allowing the MA H:Q ratio calculation. The EMG-moment relationship can also be calculated in order to account for the influence of moment during co-activation and provide a more realistic analysis of EMG H:Q ratio. For this, antagonist muscle moments can be predicted by EMG-to-moment algorithm or second order polynomial Hamstring EMG ÷ Quadriceps EMG
Hamstring EMG-moment ÷ quadriceps EMG-moment
  1. AST angle specific torque, RTD rate of torque development, FI fatigue index, MS muscle size, MT muscle thickness, ACSA anatomical cross-sectional area, MA muscle activation, EMG electromyography, PT peak torque, ROM range of motion, H:Q ratio hamstrings to quadriceps ratio, CR conventional ratio, FR functional ratio