HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Hagbarth, K E Articles by Nordin, M Search for Related Content PubMed PubMed Citation Articles by Hagbarth, K E Articles by Nordin, M

Department of Clinical Neurophysiology, University Hospital, Uppsala, Sweden.

1. In healthy human subjects holding the index finger semi-extended at the metacarpophalangeal joint against a moderate load, electromyographic (EMG) activity was recorded from the finger extensor and flexor muscles during different stages of muscle fatigue. The aim was to study the effect of muscle fatigue on the level of background EMG activity and on the reflex responses to torque pulses causing sudden extensor unloadings. Paired comparisons were made between the averaged EMG and finger deflection responses under two conditions: (1) at a stage of fatigue (following a sustained co-contraction) when great effort was required to maintain the finger position, and (2) under non-fatigue conditions while the subject tried to produce similar background EMG levels to those in the corresponding fatigue trials. 2. Both the unloading reflex in the extensor and the concurrent stretch reflex in the flexor were significantly less pronounced and had a longer latency in the fatigue trials. Consequently, the finger deflections had a larger amplitude and were arrested later in the fatigue trials. 3. It is concluded that--with avoidance of 'automatic gain compensation', i.e. reflex modifications attributable to differences in background EMG levels--the servo-like action of the unloading and stretch reflexes is reduced in fatigued finger extensor and flexor muscles.

This article has been cited by other articles:

				K. P. Granata, G. P. Slota, and S. E. Wilson Influence of Fatigue in Neuromuscular Control of Spinal Stability Human Factors: The Journal of the Human Factors and Ergonomics Society, January 1, 2004; 46(1): 81 - 91. [Abstract] [PDF]

				S. C. Gandevia Spinal and Supraspinal Factors in Human Muscle Fatigue Physiol Rev, October 1, 2001; 81(4): 1725 - 1789. [Abstract] [Full Text] [PDF]