PUBLICATIONS

AMERICAN COLLEGE of SPORTS MEDECINE Indiana, Indianapolis Convention June 1-4, 1994, volume 26, #5

EFFECTS OF SPECIFIC MECHANICAL STIMULATION IN WRIST FUNCTION. Boucher J.P., Lefebvre R., and Dr Brossard A.* Department of kinanthropology, University of Québec, Montréal, H3C 3P8

Abstracts American of Sports Medecine Indiana, Indianapolis Convention June 1-4, 1994 

AMERICAN COLLEGE of SPORTS MEDECINE Minneapolis, Minnesota, May 31-June 3, 1995 Volume 27, #5

NEUROPHYSIOLOGICAL MECHANISM UNDERLYING SPECIFIC MECHANICAL STIMULATION (SMS) FACILITATION. Boucher J-P., FACSM, Lefebvre R., Louis P-F.*, and Dr Brossard A.* Department of Kinanthropology, University of Québec at Montréal, Montréal, H3C 3P8

Last year (1994) we reported results supporting that SMS at a joint appears to facilitate muscles surrounding it and increases the efficiency of specific movements. We speculated that this gain in efficiency could be explained by the solicitation of joint or skin receptors in response to the pressure stimulus. In order to investigate the mechanism responsible for the SMS, a neurophysiological investigation of the effects of different pressure levels was conducted. The pressure was applied through special straps crossing over the sacro-iliac joint, and a modified sphymomanometer bag placed between the straps and the plastic sphere ( 1 cm diameter) overlying the joint, while the subject laid prone. Twelve asymptomatic subjects (6 men, 6 women) were tested under four different pressure levels : none (control before and after), light (straps+bag+sphere, no added pressure), medium ( added pressure = 200mmHg), and strong (added pressure = 400 mmHg). H-reflex and M response were monitored under each pressure condition. These responses were elicited through a 1ms pulse delivered to the tibial nerve (in the popliteal fossa) every 10 sec, for a total of 15 stimulations per test, with an intensity controlled to maintain the M response at 30% of its maximum value. The technique consisted then of measuring the modulation of the H-reflex accross pressure conditions while the M response remained constant, insuring a constant level of nerve stimulation. Results showed that both control tests (before and after) and medium pressure produced the same H-Reflex level (66% of Mmax). The light pressure produced a significant increase ( p=0.05) in H-reflex ( to 73% of Mmax ) while strong pressure reduced it to 63%. These results strongly suggest that SMS facilitates muscles by increasing the excitability of the motoneuron pool. Since only light pressure increased the H-reflex, it is believed that skin receptors are mediating this facilitation.