Viewing low and high wavelength light: Effect on EMG activity and force production during maximal voluntary handgrip contraction

S. M. Hasson, J. H. Williams, W. Gadberry, T. Henrich

Research output: Contribution to journalArticlepeer-review

6 Scopus citations


The purpose of this study was to determine if viewing low and high wavelength light would have an effect on force production and the electromyographic activity (EMG) of wrist/hand flexors during a maximal voluntary handgrip contraction (MVC). Fourteen healthy volunteer subjects (7 males and 7 females) participated in this investigation. Each subject viewed a projected light/color red-650nm, blue-475nm, unfiltered light, or no light (control), from within an enclosed horizontal chamber for 10-sec, and then performed a 3-sec MVC while continuing to view the projected light. MVC was measured from a handgrip dynamometer attached to a load cell, and EMG was measured from bipolar electrodes placed over the flexor carpi radialis and palmaris longus muscles. Both measurements were recorded and stored on floppy disk, and EMG raw data was rectified and integrated (IEMG) via computer computation. Six minutes of recovery in darkness followed each experimental condition. The above methods were repeated on 3 successive days with random presentation. The mean IEMG and MVC values were significantly greater (p < 0.05) for the red light than for the control (13.5% and 5.8%, respectively). There were no significant differences between the control, unfiltered light and blue light for either IEMG or MVC. This study suggests that viewing high wavelengths of light may facilitate force production and electromyographic activity in healthy individuals. Further research is necessary to determine the therapeutic effectiveness of light or color therapy in rehabilitation.

Original languageEnglish (US)
Pages (from-to)32-35
Number of pages4
JournalPhysiotherapy Canada
Issue number1
StatePublished - 1989
Externally publishedYes

ASJC Scopus subject areas

  • Physical Therapy, Sports Therapy and Rehabilitation


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