Author

Todd Luther

Date of Award

8-2015

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Physical Education

First Advisor

Peter M. McGinnis, Ph.D.

Second Advisor

James Hokanson, Ph.D.

Third Advisor

John Foley, Ph.D.

Abstract

The purpose of this study was to compare the myoelectric activity of the extensor carpi ulnaris, flexor carpi ulnaris, flexor carpi radialis, and opponens pollicis muscles while gripping a 50 lb Olympic weightlifting bar to the myoelectric activity of the same muscles while gripping a sandbag of the same weight. Myoelectric activity was measured as the average root mean square (RMS) of the surface electromyography (sEMG) values. The hypothesis was that gripping a sandbag would result in greater muscle activation of the extensor carpi ulnaris, flexor carpi ulnaris, flexor carpi radialis, and opponens pollicis muscles than gripping an Olympic weightlifting bar of the same weight. The participants were seven healthy males who performed a six second lift with the sandbag as well as a six second lift with the Olympic weightlifting bar. The order of the lifts was random. The Olympic weightlifting bar was lifted using a traditional overhand grip and the sandbag was lifted using an overhand pinching grip. In both trials the bar or sandbag was positioned at thigh height and the participant then leaned over and gripped it with both hands in front of the body. The participant then lifted the implement off its support and assumed an upright position while holding the implement in a position so that it did not touch the body other than the hands. Surface EMG electrodes detected the myoelectric activity of the extensor carpi ulnaris, flexor carpi ulnaris, flexor carpi radialis, and opponens pollicis muscles. The electrodes preamplified the myoelectric signals by a factor of 35. The sEMG signals of the four muscles were treated with a 20 Hz low cut/high pass filter, amplified by a factor of 2000, and the RMS of the filtered signals were derived using a 2.5 ms time window. The analog RMS sEMG was sampled at 1000 Hz and converted to digital form. Each muscle’s RMS sEMG was averaged over a six second period of the lift. The results of a within-subject one-tailed t-test iv indicated that the means of the subjects’ RMS sEMG for each of the four muscles were significantly larger for the sandbag lift than the Olympic bar lift. This result supported the hypothesis that gripping a sandbag produces significantly higher myoelectric activity in the extensor carpi ulnaris, flexor carpi ulnaris, flexor carpi radialis, and opponens pollicis muscles than gripping an Olympic bar of the same weight. Athletic trainers, physical therapists, strength and conditioning coaches, fitness professionals, and other health professionals can use this information to improve grip strength when designing and implementing training programs for their clients, athletes, or patients.

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