A functional fatiguing protocol and deceleration time of the shoulder from an internal rotation perturbation.

Context: Muscular fatigue impedes sensorimotor function and may increase the risk of shoulder injury during activity. The effects of fatigue on the sensorimotor system of the shoulder have been studied with various results. Deceleration times have been used to study neuromuscular control of the shoulder; however, no studies involving the effects of fatigue on deceleration times have been reported. Objective: To compare shoulder deceleration times after a shoulder internal rotation perturbation before and after a repetitive throwing exercise protocol. Design: A 2 x 2 repeated-measures design. Setting: Exercise and sport injury laboratory. Patients or Other Participants: Twenty healthy, recreationally active men (age = 24.76 +/- 4.03 years, height = 178.41 +/- 8.36 cm, mass = 80.16 +/- 15.20 kg) volunteered to participate in the study. To ensure familiarity with the overhead motion, all subjects chosen had previously participated in an overhead throwing sport. Intervention(s): The independent variables were time (preintervention and postintervention) and session (experimental and control). The intervention consisted of continuous overhead throwing. The subjects were considered fatigued when a 10% decrease in velocity was noted on 3 consecutive pitches. Main Outcome Measure(s): Time necessary to decelerate from an internal rotation perturbation. Results: Deceleration time was significantly increased by the fatiguing intervention ( P = .001). Conclusions: The decreased ability to decelerate may be an adaptive response by the subjects to dissipate a lower percentage of force per second. [ABSTRACT FROM AUTHOR]