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:: Volume 1, Issue 4 (20 2008) ::
mrj 2008, 1(4): 26-33 Back to browse issues page
The changes of motor control strategy following fatigue in extensor muscles of knee
Saied Talebian * 1, Zahra Fakhari2 , Sima Mehrdad2
1- دانشکده توانبخشی دانشگاه علوم پزشکی تهران , talebian@sina.tums.ac.ir
2- دانشکده توانبخشی‏ دانشگاه علوم پزشکی تهران
Abstract:   (14269 Views)

Background and aim:The knee joint is one of the most important joints of human body, witch tolerates many forces while the subject is standing up or walking especially during close chain and squat positions.

Muscle fatigue may causes some modifications on effects of forces and accordingly some changes on strategy of movement, therefore the concentration in thigh muscles impression on continuous movements is a guidance that makes the investigation on these changes so important.

Materials and Methods: Fifteen healthy women in the range of 20-30 years were contributed in this study. Muscle fatigue were applied in separate sessions by maximal voluntary contraction (MVC) in both open and close chains.

Subjects were done five dynamic repetitions of flexion / extension motion of knee before and after fatigue tests. Surface electromyography (sEMG) recorded from vastus medialis (VM), rectus femoris (RF) and vastus lateralis (VL) muscles during all conditions of tests. Normalized electromyography (NEMG) of muscles activities in two conditions of concentric (Con) and eccentric (Ecc), also median frequency (MF) were calculated for fatigue index. Muscle timing or recruitment pattern indicated by onset of muscle activities for both dynamics chains.

Results:  There are significant different of fatigue indexes between before and after fatigue tests (p<0.05).  After fatigue muscle timing delayed in open chain (p<0.05) and recruitment patterns changed from VL- VM- RF to VL-RF-VM. Fatigue test in close chain caused increment of muscle timing (p<0.05), but it did not change recruitment patterns.

Conclusion: After fatigue tests MF reduced little than NEMG. Significant difference occurred in muscle timing. These variations were increase and delay of timing with change of recruitment in open chain. These findings suggest that motor control strategy is will change at different condirions of with and without load situations.

Keywords: Motor Control, Muscle Fatigue, Knee Joint, Surface Electromyography, Muscle Timing
Full-Text [PDF 600 kb]   (2450 Downloads)    
Type of Study: Research | Subject: General
Received: 2008/06/22 | Accepted: 2008/08/15 | Published: 2013/07/20
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Talebian S, Fakhari Z, Mehrdad S. The changes of motor control strategy following fatigue in extensor muscles of knee. mrj 2008; 1 (4) :26-33
URL: http://mrj.tums.ac.ir/article-1-156-en.html


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Creative Commons License This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.
Volume 1, Issue 4 (20 2008) Back to browse issues page
فصلنامه توانبخشی نوین Journal of Modern Rehabilitation
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