Direct and indirect effects of joint torque inputs during an induced speed analysis of a swinging motion

Abstract

This study proposed a method to quantify direct and indirect effects of the joint torque inputs in the speed-generating mechanism of a swinging motion. Linear and angular accelerations of all segments within a multi-linked system can be expressed as the sum of contributions from a joint torque term, gravitational force term and motion-dependent term (MDT), where the MDT is a nonlinear term consisting of centrifugal force, Coriolis force and a gyroscopic effect moment. Direct effects result from angular accelerations induced by a joint torque at a given instant, whereas indirect effects arise through the MDT induced by joint torques exerted in the past. These two effects were quantified for the kicking-side leg during a rugby place kick. The MDT was the largest contributor to the foot centre of gravity (CG)'s speed at ball contact. Of the factors responsible for generating the MDT, the direct and indirect effects of the hip flexion-extension torque during both the flight phase (from the final kicking foot take-off to support foot contact) and the subsequent support phase (from support foot contact to ball contact) were important contributors to the foot CG's speed at ball contact. The indirect effect of the ankle plantar-dorsal flexion torque and the direct effect of the knee flexion-extension torque during the support phase showed the largest positive and negative contributions to the foot CG's speed at ball contact, respectively. The proposed method allows the identification of which individual joint torque axes are crucial and the timings of joint torque exertion that are used to generate a high speed of the distal point of a multi-linked system.

Relationships between Racket Arm Joint Moments and Racket Head Speed during the Badminton Jump Smash Performed by Elite Male Malaysian Players

“…The racket model (two rigid segments connected by a virtual joint) is a simplification of the dynamic behaviour of a racket, which adopts an infinite number of mode shapes under loading; however, the current approach has been used previously to measure racket kinematics [15]. Future work should also aim to understand the direct vs. indirect effects of the torques within the smash with respect to the generation of speed [28], i.e., whether the high speeds generated are a result of instantaneous torques produced by the musculature at the joint or developed by cumulative torques from prior torques at other joints. The 'resultant moments' approach used in this study does not allow a distinction between muscular, gravitational and velocity-dependent torques and therefore specific recommendations for strengthening specific muscle groups should be made with caution.…”

Quantification of a Ball-Speed Generating Mechanism of Baseball Pitching Using IMUs

“…The rigid link model and the locations of the IMUs attached to the segments are shown in Figure 1a,b. Anatomical constraint axes (e.g., varus/valgus axis at the elbow joint; internal/external rotation axis at the wrist joint), along which the joints could not rotate freely, were considered [6]. Since the ball was assumed to be fixed to the hand segment coordinate system during the pitching motion, the hand and ball were assumed to be one rigid segment in this study.…”

A study on derivation method of motion feature points in sports motion analysis for racket matching

“…Koike proposed an equation of motion consisting of a joint torque term, a gravitational term, and a motion-dependent term consisting of centrifugal forces and Coriolis forces. It was shown that the contribution of each term greatly differs depending on which exercise is focused (Koike et al, 2019).…”