Testing Applicability of the Leading Joint Hypothesis in Frisbee-like Throwing

Abstract

Record ID: 214

Award(s): Excellence in Undergraduate Research Mentorship; Excellence in Research Communication

Program Affiliation: McNair Scholars Program

Presentation Type: Poster

Abstract: Humans exhibit a broad spectrum of skilled perceptual-motor behaviors, from typing to playing tennis, yet the central nervous system's regulation of the musculoskeletal system's elements is not fully understood. The Leading Joint Hypothesis (LJH) offers a perspective on multi-joint movements, suggesting that for each action, there is a primary "leading joint" while secondary "trailing joints" follow, experiencing passive "interaction" torque generated by the leading joint. This implies active muscle control is only needed for the leading joint, with trailing joints requiring intermittent control to channel interaction torques to produce a desired movement of the whole limb. This study aims to investigate the joint interaction pattern in frisbee-like throwing. Five participants performed frisbee-like throws in horizontal plane using their elbow and wrist under conditions of slow-velocity and fast-velocity throws, with instructions to relax their wrist. Kinematic data on the arm, forearm, and wrist movements were captured using inertial measurement units, alongside electromyography on bicep, triceps, and forearm muscles to record muscle activation. LJH predicts that during both fast-velocity throws, the IMU and EMG recordings will show the earliest muscle activity at the triceps muscle (indicating it as a leading joint), with no muscle coactivation at the wrist muscles (trailing joint). However, during slow-velocity throwing and no-throwing conditions, we expect muscle activation at both the leading and trailing joint(s). The study aims to test the applicability of the LDJ in frisbee-like throwing. Theoretical ideas of LDJ can be helpful to improve motor learning in sports and rehabilitation.