Effect of fatigue and the absence of visual feedback on shoulder motor control in an healthy population during a reaching task

Abstract Introduction The main role of the upper limb is to position the hand in order to carry out varied activities requiring coordinated multi-joint movement, which requires mobility and stability at the glenohumeral joint. This is made possible by the interaction between active and passive structures as well as the integration of information coming from multiple systems. This interaction can be compromised by factors such as muscle fatigue and lack of visual feedback, leading to decreased performance. Several studies have investigated their isolated effect without looking at their combined effect. Objective To measure the specific and the combined effects of shoulder muscles fatigue and of lack of visual feedback on shoulder motor control during a reaching task with the arm in an elevated position. Methods 60 healthy participants were randomly assigned to one of four experimental groups: 1) control with visual feedback; 2) control without visual feedback; 3) fatigue with visual feedback; 4) fatigue without visual feedback. Subjects had to perform 10 trials of a reaching task in the KINARM robotic arm. Kinematic variables of interest were time taken to complete the task, final error, initial angle of deviation and area under curve. Non-parametric ANOVAs were used. Results Analyses showed that there were statistically significant differences (p  Conclusion Findings show that lack of visual feedback had an impact on the reaching task performance while fatigue did not. In addition, fatigue did not increase the effect of the lack of visual feedback.