RAPID MOVEMENT KINEMATIC AND ELECTROMYOGRAPHIC CONTROL CHARACTERISTICS IN MALES AND FEMALES

Maximally fast, self-terminated elbow flexion movements were performed by 10 male and 10 female college-aged subjects to assess potential ge nder-related differences in kinematics and the triphasic electromyogra phic (EMG) pattern. The subjects were instructed to move their forearm s as fast as possible through 90-degrees of elbow flexion range of mot ion and stop as sharply as possible at the terminal point. An electrom agnet, set to 0, 40, and 70% of each subject's maximal isometric torqu e, provided resistance to movement initiation and resulted in quick re lease movements. Surface EMG was collected from the biceps b. and tric eps b. muscles. Results indicated that the males had faster movements and accelerations under all conditions. EMG records indicated that the males had faster rates of EMG rise, particularly in the triceps b., a nd more tightly coupled reciprocal activation. The quick release affor ded faster accelerations for both groups, yet only the males moved fas ter throughout the full range of motion. Following the quick release, the males differed from the females by increasing the triceps b. EMG a mplitude. Hence, the males were able to shorten movement time in quick release movements by increasing triceps b. activation and, thus, brak ing ability. These results suggest that the females were more neurally constrained than the males with respect to rapid EMG activation of th e triceps b., resulting in limits in the braking process.