1. Conventional Concentric H:Q Ratio (Hcon:Qcon)
The conventional H:Q ratio is calculated by dividing concentric hamstring peak torque by concentric quadriceps peak torque at identical angular velocities:
At 60°/s, normative values for uninjured populations range from 60% to 70% (0.60–0.70). As velocity increases to 240°/s or 300°/s, the conventional ratio rises to 70–80% because quadriceps concentric torque declines more rapidly than hamstring torque along the force-velocity curve.
2. Functional Dynamic Control Ratio (Hecc:Qcon)
While the conventional ratio measures two concentric actions, movement in sport requires reciprocal muscle action. During aggressive terminal knee extension (such as kicking, sprinting, or landing), the quadriceps contract concentrically while the hamstrings contract eccentrically to decelerate tibial rotation.
At high angular velocities (240°/s), a functional ratio ≥ 1.0 indicates that eccentric hamstring braking capability exceeds concentric quadriceps extension force, providing superior dynamic joint protection.