Recovery of Joint Position Sense in the Shoulder after Muscle Fatigue

Abstract

Context:Fatigue of the shoulder rotator muscles may negatively affect joint position sense (JPS) and ultimately lead to injury.Objective:Recovery of shoulder JPS after muscle fatigue.Design:A repeated-measures study.Setting:Musculoskeletal research laboratory.Patients:Thirteen subjects participated in joint position error tests and isokinetic concentric strength assessment in shoulder rotation, before and after rotator muscle fatigue.Interventions:Local muscle fatigue was induced using isokinetic concentric contractions of the shoulder rotator muscles.Main Outcome Measurements:Shoulder rotator strength and JPS error signals were measured before fatigue, immediately after fatigue, and every ten minutes thereafter for one hour.Results:Before shoulder rotation muscle fatigue, the accuracy of shoulder JPS was 2.79 ± 1.67 degrees. After muscle fatigue, the accuracy decreased to 6.39 ± 2.90 degrees. Shoulder JPS was influenced up to 40 minutes after muscle fatigue, but shoulder strength was only affected for 10 minutes after muscle fatigue.Conclusions:Proprioceptive recovery was slower than strength following fatigue of the shoulder rotators.