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 Milner-Brown, H S Articles by Stein, R B Search for Related Content PubMed PubMed Citation Articles by Milner-Brown, H S Articles by Stein, R B

1. Motor units in the first dorsal interosseus muscle of normal human subjects were recorded by needle electrodes, together with the surface electromyogram (e.m.g.). The wave form contributed by each motor unit to the surface e.m.g. was determined by signal averaging. 2. The peak-to-peak amplitude of the wave form contributed to the surface e.m.g. by a motor unit increased approximately as the square root of the threshold force at which the unit was recruited. The peak-to-peak duration of the wave form was independent of the threshold force. 3. Large and small motor units are uniformly distributed throughout this muscle, and the muscle fibres making up a motor unit may be widely dispersed. 4. The rectified surface e.m.g. was computed as a function of force, based on the sample of motor units recorded. The largest contribution of motor unit recruitment occurs at low force levels, while the contribution of increased firing rate becomes more important at higher force levels. 5. Possible bases for the common experimental observation that the mean rectified surface e.m.g. varies linearly with the force generated by a muscle are discussed. E.m.g. potentials and contractile responses may both sum non-linearly at moderate to high force levels, but in such a way that the rectified surface e.m.g. is still approximately linearly related to the force produced by the muscle.

This article has been cited by other articles:

				K. G. Keenan and F. J. Valero-Cuevas Experimentally Valid Predictions of Muscle Force and EMG in Models of Motor-Unit Function Are Most Sensitive to Neural Properties J Neurophysiol, September 1, 2007; 98(3): 1581 - 1590. [Abstract] [Full Text] [PDF]

				K. G. Keenan, D. Farina, F. G. Meyer, R. Merletti, and R. M. Enoka Sensitivity of the cross-correlaton between simulated surface EMGs for two muscles to detect motor unit synchronization J Appl Physiol, March 1, 2007; 102(3): 1193 - 1201. [Abstract] [Full Text] [PDF]

				K. G. Keenan, D. Farina, R. Merletti, and R. M. Enoka Amplitude cancellation reduces the size of motor unit potentials averaged from the surface EMG J Appl Physiol, June 1, 2006; 100(6): 1928 - 1937. [Abstract] [Full Text] [PDF]

				L. L Andersen, S P. Magnusson, M. Nielsen, J. Haleem, K. Poulsen, and P. Aagaard Neuromuscular Activation in Conventional Therapeutic Exercises and Heavy Resistance Exercises: Implications for Rehabilitation Physical Therapy, May 1, 2006; 86(5): 683 - 697. [Abstract] [Full Text] [PDF]

				D. M. Wallace, B. H. Ross, and C. K. Thomas Motor unit behavior during clonus J Appl Physiol, December 1, 2005; 99(6): 2166 - 2172. [Abstract] [Full Text] [PDF]

				P. Zhou and W. Z. Rymer Factors Governing the Form of the Relation Between Muscle Force and the EMG: A Simulation Study J Neurophysiol, November 1, 2004; 92(5): 2878 - 2886. [Abstract] [Full Text] [PDF]

				P. Bawa, G. R. Chalmers, H. Stewart, and A. A. Eisen Responses of Ankle Extensor and Flexor Motoneurons to Transcranial Magnetic Stimulation J Neurophysiol, July 1, 2002; 88(1): 124 - 132. [Abstract] [Full Text] [PDF]

				S. J. Day and M. Hulliger Experimental Simulation of Cat Electromyogram: Evidence for Algebraic Summation of Motor-Unit Action-Potential Trains J Neurophysiol, November 1, 2001; 86(5): 2144 - 2158. [Abstract] [Full Text] [PDF]

				S. Perrey, A. Betik, R. Candau, J. D. Rouillon, and R. L. Hughson Comparison of oxygen uptake kinetics during concentric and eccentric cycle exercise J Appl Physiol, November 1, 2001; 91(5): 2135 - 2142. [Abstract] [Full Text] [PDF]

				S. L. Pullman, D. S. Goodin, A. I. Marquinez, S. Tabbal, and M. Rubin Clinical utility of surface EMG: Report of the Therapeutics and Technology Assessment Subcommittee of the American Academy of Neurology Neurology, July 25, 2000; 55(2): 171 - 177. [Full Text] [PDF]

				W. Yao, R. J. Fuglevand, and R. M. Enoka Motor-Unit Synchronization Increases EMG Amplitude and Decreases Force Steadiness of Simulated Contractions J Neurophysiol, January 1, 2000; 83(1): 441 - 452. [Abstract] [Full Text] [PDF]

				A. P. Harrison and J. A. Flatman Measurement of force and both surface and deep M wave properties in isolated rat soleus muscles Am J Physiol Regulatory Integrative Comp Physiol, December 1, 1999; 277(6): R1646 - R1653. [Abstract] [Full Text] [PDF]

				A. J. Fuglevand and S. S. Segal Simulation of motor unit recruitment and microvascular unit perfusion: spatial considerations J Appl Physiol, October 1, 1997; 83(4): 1223 - 1234. [Abstract] [Full Text] [PDF]

				B. A. Lavoie, H. Devanne, and C. Capaday Differential Control of Reciprocal Inhibition During Walking Versus Postural and Voluntary Motor Tasks in Humans J Neurophysiol, July 1, 1997; 78(1): 429 - 438. [Abstract] [Full Text] [PDF]

				T. P. Branch, R. Hunter, and M. Donath Dynamic EMG analysis of anterior cruciate deficient legs with and without bracing during cutting Am. J. Sports Med., January 1, 1989; 17(1): 35 - 41. [Abstract] [PDF]