Upper extremity kinematics and joint coordination of fly-casting

Abstract

Little research exists that focuses on the motions and coordination common to fly-casting. It was hypothesized that kinematic parameters of casting (peak and total range of motion, timing of peak joint angular velocity, and magnitude of peak joint angular velocity) would increase in order to cast lines of greater length. Also, it was hypothesized that when greater length of line is cast, the time between peak angular velocities would decrease. The purpose of this study was to determine the kinematic and joint coordination changes necessary to cast lines of different length. Eighteen male subjects participated in the study. Experience ranged from intermediate to expert, with a number of the subjects being professional fly-fishing guides. Twenty three reflective markers were tracked by a 6-camera Vicon® digital capture system. Shoulder motion was calculated with respect to the trunk. The elbow was modeled as a uni-axial pin joint and the wrist as a bi-axial pin joint.

Subjects performed casts at conditions of 20, 40, 60, and 80 ft. A MANOVA was used to assess effect of line length. The fly casting motion was divided into three primary phases; back cast, pause, and forward cast. Overall, total ROM increased with increased length of line cast. However, wrist radial/ulnar deviation (RD/UD) total ROM changed little across all distances and wrist flexion/extension (F/E) total ROM decreased with increased line length. Peak angular velocity exhibited a proximal-to-distal trend during the forward cast; first peak shoulder internal rotation, then elbow extension and lastly, wrist ulnar deviation. Time between peak angular velocities did not decrease with increased line length. Time between peak shoulder and elbow angular velocities actually increased (p = 0.037) as line length increased. Findings indicate that significant changes in total ROM were needed to accommodate the demands of casting greater lengths of line. Also, joint velocity coordination patterns of fly-casting appear to follow a proximal-to-distal pattern.