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aferris18
04-09-2007, 10:33 AM
Greetings Colleagues!



I am currently working on a pilot study involving a vibration platform. We are interested in measuring muscle activity while performing various exercises on the platform while it is turned on. Currently, we are performing an isometric squat exercise. The subject is initially standing on the platform, squats to a predetermined depth (90), holds the squat and then the platform is turned on. We note a large increase in muscle activity immediately when the platform is turned on. However, after performing a FFT analysis, we note a single peak in the frequency spectrum coinciding with the frequency of the vibrations. The magnitude of the peak is at least 8 times that of any other frequency within the signal. Because of the magnitude of the spike at this frequency, I am inclined to consider this noise from the platform and to notch this frequency out of the signal. However, a few recent studies suggest these platforms may act to stimulate a reflex response from the muscle and thereby causing the muscle to contract at the same rate of the vibrations. I have preformed tests on a foam block strapped to the machine and placed electrodes on it and found similar results, but again, this is not a biological system and thus extrapolating the results to human subjects is difficult. Has anyone else had any experience with these platforms and EMG? Could anyone suggest a method by which we might be able to distinguish between true biological signal and noise? Any help or suggestions would be greatly appreciated and welcomed!!



Best regards!

Abbie





Abbie Ferris M.S.

Doctoral Student

University of Southern California

Musculoskeletal Biomechanics Research Laboratory (MBRL)

http://www.usc.edu/go/mbrl

1540 Alcazar St, CHP-155

Los Angeles, CA 90089-9006

(323) 442-2948