Accession Number : AD0766580

Title :   On the Control of Postural Muscles During Some Natural Human Movements,

Corporate Author : MCGILL UNIV MONTREAL (QUEBEC) DRB AVIATION MEDICAL RESEARCH UNIT

Personal Author(s) : Jones,G. Melvill ; Watt,D. G. D.

Report Date : 1971

Pagination or Media Count : 7

Abstract : Previous work by Hammond et al. (1956) demonstrated that sudden, maintained stretch of the human biceps muscle resulted in a monosynaptic electromyographic response at 15 msec, and a polyphasic burst at 35 msec after the onset of the stretch. While the latter burst resulted in a significant build-up of tension in the muscle, the monosynaptic response did not. It was initially demonstrated in this laboratory that a similar response occurred in the human gastrocnemius muscle. The latency of this response, called by us the functional stretch reflex (FSR), was 120 msec. The significance of the FSR in the gastrocnemius was then investigated during the natural human movements of stepping to the ground and repetitive hopping. It was shown that all EMG activity in the gastrocnemius concerned with the control of landing from a single step to the ground was completed before the FSR had a chance to contribute. During repetitive hopping while the landing phase of each hop appeared to be similarly pre-programmed, the take-off phase was timed in such a way as to make use of the FSR. The possibility of the FSR being a long-loop reflex is discussed, and some evidence is given to support this hypothesis. (Author)

Descriptors :   (*POSTURE(PHYSIOLOGY), MUSCLES), (*MUSCLES, CONTROL), REFLEXES, CONTRACTION, ELECTROMYOGRAPHY, HUMANS, PHYSIOLOGY, CANADA

Subject Categories : Anatomy and Physiology

Distribution Statement : APPROVED FOR PUBLIC RELEASE