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Movement Accuracy Changes Muscle-Activation Strategies in Female Subjects During a Novel Single-Leg Weight-Bearing Task
Journal article   Open access

Movement Accuracy Changes Muscle-Activation Strategies in Female Subjects During a Novel Single-Leg Weight-Bearing Task

Sangeetha Madhavan and Richard K Shields
PM & R, Vol.1(4), pp.319-328
2009
DOI: 10.1016/j.pmrj.2009.01.002
PMCID: PMC2763312
PMID: 19627914
url
https://www.ncbi.nlm.nih.gov/pmc/articles/2763312View
Open Access

Abstract

Understanding of how female subjects learn to move accurately during a resisted weight-bearing task is limited. The purpose of this study was to examine the muscle activation patterns used by female subjects in learning a novel single-leg squat (SLS) task under visual and nonvisual conditions. Prospective training study. University research setting. Ten healthy young female participants. Subjects tracked a sinusoidal target (knee displacement) during a resisted SLS exercise during the course of 4 days, under eyes open (EO) and eyes closed (EC) conditions with the use of a custom-designed weight-bearing exercise device. The accuracy of performance in tracking the target and electromyographic activity (EMG) of 5 muscles around the knee were monitored. Subjects improved their accuracy of performance by day 2 (40% decrease in error) and retained the accuracy on day 4. Error during the EC condition was 3 times greater than EO condition. Quadriceps-to-hamstrings coactivation ratio increased with the improved accuracy from the learning. Absence of visual feedback was accompanied by a decrease in the quadriceps-to-hamstrings coactivation ratio for this task. The muscle synergistic activity around the knee changes as the accuracy of the task improves during a resisted weight-bearing task. This activation pattern represents a feed forward control plan that the central nervous system adopted to optimize accurate weight-bearing knee displacement. Rehabilitation specialists should consider manipulating the visual feedback and accuracy of performance when developing weight-bearing rehabilitation training protocols to improve neuromuscular control in female patients.

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