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

TY - JOUR

T1 - Rate of torque development scaled to maximum torque available is velocity dependent

AU - Tillin, Neale A.

AU - Hessel, Anthony

AU - Ang, Shaun

PY - 2021/1/4

Y1 - 2021/1/4

N2 - 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 (Tmax) being well-established. This study investigated the relationship between angular velocity and RTD scaled to Tmax. In 17 participants, tetanic contractions (100-Hz) of the knee extensors were evoked as the knee was passively extended at different iso-velocities between 0º.s-1 to 200º.s-1. Each condition consisted of evoking 0.25-s contractions without pre-activation (for measuring RTD) commencing as the knee passed 95º of extension, and 1.25-s contractions with pre-activation (for measuring Tmax), commencing 1 s prior to the knee reaching 95º. Torque at 100 ms after torque onset (T100) and peak RTD (RTDpeak) in the contractions without pre-activation were normalised to Tmax. The torque-velocity relationship for T100 was flat in comparison to an inverse, curvilinear relationship for Tmax, resulting in linear increases in normalised T100 and RTDpeak with increased velocity. Results also showed normalised T100 and RTDpeak 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 Tmax increases with increased velocity, which appears to be an intrinsic contractile property independent of the effects of force depression. © 2021, Elsevier. This is an author produced version of a paper published in Journal of Biomechanics uploaded in accordance with the publisher’s self- archiving policy. The final published version (version of record) is available online at the link. Some minor differences between this version and the final published version may remain. We suggest you refer to the final published version should you wish to cite from it.

AB - 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 (Tmax) being well-established. This study investigated the relationship between angular velocity and RTD scaled to Tmax. In 17 participants, tetanic contractions (100-Hz) of the knee extensors were evoked as the knee was passively extended at different iso-velocities between 0º.s-1 to 200º.s-1. Each condition consisted of evoking 0.25-s contractions without pre-activation (for measuring RTD) commencing as the knee passed 95º of extension, and 1.25-s contractions with pre-activation (for measuring Tmax), commencing 1 s prior to the knee reaching 95º. Torque at 100 ms after torque onset (T100) and peak RTD (RTDpeak) in the contractions without pre-activation were normalised to Tmax. The torque-velocity relationship for T100 was flat in comparison to an inverse, curvilinear relationship for Tmax, resulting in linear increases in normalised T100 and RTDpeak with increased velocity. Results also showed normalised T100 and RTDpeak 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 Tmax increases with increased velocity, which appears to be an intrinsic contractile property independent of the effects of force depression. © 2021, Elsevier. This is an author produced version of a paper published in Journal of Biomechanics uploaded in accordance with the publisher’s self- archiving policy. The final published version (version of record) is available online at the link. Some minor differences between this version and the final published version may remain. We suggest you refer to the final published version should you wish to cite from it.

KW - Rate of force development

KW - intrinsic contractile properties

KW - force - velocity relationship

KW - muscle strength

KW - residual force depression

KW - concentric contractions

U2 - 10.1016/j.jbiomech.2020.110144

DO - 10.1016/j.jbiomech.2020.110144

M3 - Article

SN - 0021-9290

VL - 114

JO - Journal of Biomechanics

JF - Journal of Biomechanics

M1 - 110144

ER -