Rate of torque development scaled to maximum torque available is velocity dependent

The influence of angular velocity on rate of torque development (RTD) is unknown, despite the inverse, curvilinear torque-velocity relationship for angle- and velocity-specific maximum available torque (T_max) being well-established. This study investigated the relationship between angular velocity and RTD scaled to T_max. In 17 participants, tetanic contractions (100-Hz) of the knee extensors were evoked as the knee was passively extended at different iso-velocities between 0° s^-1 and 200° s^-1. Each condition consisted of evoking 0.25-s contractions without pre-activation (for measuring RTD) commencing as the knee passed 95° of extension, and 1.25-s contractions with pre-activation (for measuring T_max), commencing 1 s prior to the knee reaching 95°. Torque at 100 ms after torque onset (T₁₀₀) and peak RTD (RTD_peak) in the contractions without pre-activation were normalised to T_max. The torque-velocity relationship for T₁₀₀ was flat in comparison to an inverse, curvilinear relationship for T_max, resulting in linear increases in normalised T₁₀₀ and RTD_peak with increased velocity. Results also showed normalised T₁₀₀ and RTD_peak were likely overestimated due to shortening-induced force depression (FD) which would be greater in contractions with- than without- pre-activation. However, these effects of FD cannot explain the faster normalised RTD with increased velocity, as the relative difference in work done (a proxy for FD) between contractions with and without pre-activation decreased - and thus the overestimation of normalised RTD metrics likely decreased - with increased velocity. In conclusion, RTD scaled to T_max increases with increased velocity, which appears to be an intrinsic contractile property independent of the effects of force depression.