p< e-mail: m.abbaszadeh@mubabol.ac.ir

strain gauge (repeatability) (accuracy) SG110 EMG SENIAM ASIS Biodex Medical System, Inc., Shirley, New York, Drouin Biometrics (EMG) DataLog RMS Band pass filter: 20 Hz-450Hz Gain: 50 v/div Sampling frequency: 1000 Hz Biometrics Data log

The effect of Fatigue, Velocity and Interaction of Them J Babol Univ Med Sci; 11(2); Jun- Jul 2009 ; Kh. Khademi Kalantari, et al Repeated Measure ANOVA Paired Repeated Measure ANOVA T-Test ST-VM BF-VM ST-VL BF-VL ST-RF BF-RF VL ST RF BF VM

The effect of Fatigue, Velocity and Interaction of Them J Babol Univ Med Sci; 11(2); Jun- Jul 2009 ; Kh. Khademi Kalantari, et al Co-contraction CNS Coactivation rate p< servo-system Billaut negative work Thelen

The effect of Fatigue, Velocity and Interaction of Them J Babol Univ Med Sci; 11(2); Jun- Jul 2009 ; Kh. Khademi Kalantari, et al The Effect of Fatigue, Velocity and Interaction of Them on the Inter- Muscular Coordination of Hamstring and Quadriceps Muscle Kh. Khademi Kalantari (PhD) 1, M. Abbaszadeh Amirdehi (MSc) 2, S. Talebian Moghadam (PhD) 3, M. Hadian (PhD) 4 1. Associate Professor of Physiotherapy, Rehabilitation School, Shaheed Beheshti University of Medical Sciences, Tehran, Iran 2. MSc in Physiotherapy, Babol University of Medical Sciences, Babol, Iran 3. Associate Professor of Physiotherapy, Rehabilitation School, Tehran University of Medical Sciences, Tehran, Iran 4. Professor of Physiotherapy, Rehabilitation School, Tehran University of Medical Sciences, Tehran, Iran Received: Dec 14 th 2008, Revised: Feb 18 th 2009, Accepted: May 13 th 2009. ABSTRACT BACKGROUND AND OBJECTIVE: Due to aspect of biomechanical and neuromuscular, intermuscular coordination have a major role in function of knee joint and prevention of knee joint injuries. The purpose of this study was to characterize the effect of velocity and fatigue on the intermuscular coordination of hamstrings and quadriceps muscles. METHODS: This study is quasi-experimental that was done on 31 healthy and non-athletic subjects (24 women, 7 men) aged between 20-30 years. They were selected by convenience non-probable sampling method. Subjects performed sixty knee flexion and extension with maximum voluntary effort at the velocity of 45 /s. Surface EMG of quadriceps and hamstring muscles was recorded for the study of EMG onset time during extension of the knee joint in the velocities 45 /s, 150 /s and 300 /s by isokinetic dynamometer before and after fatigue. Then data were compared. FINDINGS: The findings showed in various velocities of fatigue and non fatigue conditions, EMG onset of hamstring muscles related to quadriceps muscles are delayed. The average of these delayed time decreased with increasing velocity in non-fatigue condition: 45 /s=74.3±13.2 ms, 150 /s=50±7.5 ms, 300 /s=53.8±7.2 ms (p<0.05) and in fatigue condition: 45 /s=68±8.8 ms, 150 /s=50.8±11.6 ms, 300 /s=48.3±4.4 ms) did not change with increasing velocity. CONCLUSION: The results of this research showed that higher velocity have more effect on delay onset time of hamstrings and quadriceps muscles activations. In fact, we can say that significant changes are related to effect of velocity not fatigue. KEY WORDS: Coordination, Knee, Muscle fatigue, Velocity, Electromyography. Corresponding Author; Address: Physiotherapy Department, Shahid Yahyanejad hospital, Babol, Iran E-mail: m.abbaszadeh@mubabol.ac.ir

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