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Year : 2014  |  Volume : 1  |  Issue : 1  |  Page : 20-24

Examination of muscle activity with an elastic hamstring assistance device

1 School of Kinesiology, University of Louisiana at Lafayette, Lafayette, Louisiana, USA
2 School of Physical Education, Sport and Exercise, Science Ball State University, Muncie, Indiana, USA

Correspondence Address:
David Bellar
School of Kinesiology, University of Louisiana at Lafayette, 225 Cajundome Blvd, Lafayette - 70508, Louisiana
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/2394-2010.143321

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Background: Hamstring injuries are common among athletes and recreationally active people. The goal of the study was to determine if the Hamstrong device was effective in reducing the activity of the hamstring muscles during isometric knee exercise. Materials and Methods: Electrodes were placed on the biceps femoris and semitendinosus in a bipolar configuration on the left leg of all the subjects (N = 12) in order to monitor muscle activity during the experimental procedure. The test involved isometrically holding 15%, 30%, 45%, and 60% of the participant's pre-determined maximum isometric force at 90° and 135° knee extension with and without the Hamstring apparatus. The raw electromyography (EMG) signal was low-pass filtered and amplified prior to being interpreted. Results: There was a significant difference in the signal from the biceps femoris determined via surface electromyography (sEMG) at 90 degrees of knee extension using 30% of peak isometric force as the load (P = 0.043). Additionally in the biceps femoris there were differences in the sEMG signal at 135 degrees of knee extension using 15% (P = 0.0492) and 30% (P = 0.0358) of peak isometric force. In the semitendinosus muscle, there was a significant difference in sEMG signal at 15° of knee extension with 60% of peak isometric force (P = 0.0025). Overall, clinical inferences revealed that the device could be considered 71.4% beneficial or substantially positive to 10.9% for reducing the EMG signal associated with isometric exercise in the biceps femoris (biceps femoris mean: With device 0.319 mV ± 0.13 and without device 0.361 mV ± 0.14). Similarly, six out of eight conditions resulted in lower muscle activation from the semitendinosus with the apparatus. For the semitendinosus muscle, the range was from 43.9% beneficial to 0.1% beneficial (semitendinosus mean: With device 0.327 mV ± 0.09 and without device 0.339 mV ± 0.09). Conclusion: The reduction in electrical activity of the biceps femoris and the semitendinosus during the isometric hold with the Hamstring apparatus suggests that the elastic hamstring assistance device effectively assists in knee flexion and could potentially be used for rehabilitation purposes.

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