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BioMed Research International
Volume 2014, Article ID 623191, 8 pages
Research Article

Angular Velocity Affects Trunk Muscle Strength and EMG Activation during Isokinetic Axial Rotation

1Department of Rehabilitation Medicine, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China
2Department of Rehabilitation Medicine, Binzhou Medical University Hospital, Binzhou 256603, China
3Department of Orthopaedics and Traumatology, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China

Received 3 January 2014; Accepted 11 March 2014; Published 8 April 2014

Academic Editor: P. Bryant Chase

Copyright © 2014 Jian-Zhong Fan et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Objective. To evaluate trunk muscle strength and EMG activation during isokinetic axial rotation at different angular velocities. Method. Twenty-four healthy young men performed isokinetic axial rotation in right and left directions at 30, 60, and 120 degrees per second angular velocity. Simultaneously, surface EMG was recorded on external oblique (EO), internal oblique (IO), and latissimus dorsi (LD) bilaterally. Results. In each direction, with the increase of angular velocity, peak torque decreased, whereas peak power increased. During isokinetic axial rotation, contralateral EO as well as ipsilateral IO and LD acted as primary agonists, whereas, ipsilateral EO as well as contralateral IO and LD acted as primary antagonistic muscles. For each primary agonist, the root mean square values decreased with the increase of angular velocity. Antagonist coactiviation was observed at each velocity; however, it appears to be higher with the increase of angular velocity. Conclusion. Our results suggest that velocity of rotation has great impact on the axial rotation torque and EMG activity. An inverse relationship of angular velocity was suggested with the axial rotation torque as well as root mean square value of individual trunk muscle. In addition, higher velocity is associated with higher coactivation of antagonist, leading to a decrease in torque with the increase of velocity.