Scaling of Joint Motion and Muscle Activation for 3-Dimensional Control of Reach Extent

Abstract

This study investigated the scaling of upper arm kinematics, joint motion, and muscle activation for three-dimensional (3D) reaches to targets of increasing distance. Fifteen participants completed 108 total reaches to targets placed 7, 14, and 21 cm across midline. Peak velocity, acceleration, and time to peak velocity scaled to both target and movement distance. Shoulder and elbow excursion scaled to target distance and were highly coordinated. Anterior deltoid activation scaled to both target and movement distance in the early and late phases of reach control. Biceps and triceps activation scaled to movement distance primarily in the late phase. Scaling of these outcome variables provides a model for understanding the control of reach distance in a 3D environment.

Keywords:

• motor control
• reaching
• joint coordination
• feedforward
• feedback

Disclosure Statement

No potential competing interest was reported by the author(s).

Additional information

Funding

This study was supported by grants from the American Heart Association (15SDG2497001), University of South Carolina Office of Research (ASPIRE-I), the University of South Carolina Office of Undergraduate Research (Magellan Scholar).