Multiple features of motor-unit activity influence force fluctuations during isometric contractions

Journal of Neurophysiology

Volumn 90, Issue 2, 2003, Pages 1350-1361

  Taylor, Anna M ^a   Christou, Evangelos A ^a   Enoka, Roger M ^a  

^a UNIVERSITY OF COLORADO   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

ADULT; ARTICLE; FEMALE; FINGER; HAND MUSCLE; HUMAN; HUMAN EXPERIMENT; MALE; MOTOR UNIT; MUSCLE CONTRACTION; MUSCLE FORCE; MUSCLE ISOMETRIC CONTRACTION; NORMAL HUMAN; PRIORITY JOURNAL; VOLUNTARY MOVEMENT;

ADULT; COMPUTER SIMULATION; ELECTROMYOGRAPHY; FEMALE; HUMANS; ISOMETRIC CONTRACTION; MALE; MUSCLE, SKELETAL; REFERENCE VALUES;

EID: 0041315416     PISSN: 00223077     EISSN: None     Source Type: Journal    
DOI: 10.1152/jn.00056.2003     Document Type: Article

References (37)

1. Allen GM, Gandevia SC, and McKenzie DK. Reliability of measurements of muscle strength and voluntary activation using twitch interpolation. Muscle Nerve 18: 593-600, 1995.
2. Burnett RA, Laidlaw DH, and Enoka RM. Coactivation of the antagonist muscle does not covary with steadiness in old adults. J Appl Physiol 89: 61-71, 2000.
3. Christou EA, Grossman M, and Carlton LG. Modeling variability of force during isometric contractions of the quadriceps femoris. J Mot Behav 34: 67-81, 2002.
4. Clamann HP and Schelhorn TB. Nonlinear force addition of newly recruited motor units in the cat hindlimb. Muscle Nerve 11: 1079-1089, 1988.
5. Day SJ and Hulliger M. Experimental simulation of cat electromyogram: evidence for algebraic summation of motor-unit action-potential trains. J Neurophysiol 86: 2144-2158, 2001.
6. De Luca CJ, LeFever RS, McCue MP, and Xenakis AP. Control scheme governing concurrently active human motor units during voluntary contractions. J Physiol 329: 129-142, 1982.
7. Enoka RM, Christou EA, Hunter SK, Kornatz KW, Semmler JG, Taylor AM, and Tracy BL. Mechanisms that contribute to differences in motor performance between young and old adults. J Electromyogr Kinesiol 13: 1-12, 2003.
8. Enoka RM and Fuglevand AJ. Motor unit physiology: some unresolved issues. Muscle Nerve 24: 4-17, 2001.
9. Farmer SF. Rhythmicity, synchronization and binding in human and primate motor systems. J Physiol 509: 3-14, 1998.
10. Fuglevand AJ, Winter DA, and Patla AE. Models of recruitment and rate coding organization in motor-unit pools. J Neurophysiol 70: 2470-2488, 1993.
11. Halliday DM, Conway BA, Farmer SF, and Rosenberg JR. Load-independent contributions from motor-unit synchronization to human physiological tremor. J Neurophysiol 82: 664-675, 1999.
12. Jones KE, Hamilton A, and Wolpert DM. The sources of signal-dependent noise during isometric force production. J Neurophysiol 88: 1533-1544, 2002.
13. Keen DA, Yue GH, and Enoka RM. Training-related enhancement in the control of motor output in elderly humans. J Appl Physiol 77: 2648-2658, 1994.
14. Kornatz KW, Christou EA, and Enoka RM. Steadiness training reduces the variability of motor unit discharge rate in isometric and anisometric contractions performed by old adults. Soc Neurosci Abstr 28: 665.10, 2002.
15. Laidlaw DH, Bilodeau M, and Enoka RM. Steadiness is reduced and motor unit discharge is more variable in old adults. Muscle Nerve 23: 600-612, 2000.
16. Laidlaw DH, Kornatz KW, Keen DA, Suzuki S, and Enoka RM. Strength training improves the steadiness of slow lengthening contractions performed by old adults. J Appl Physiol 87: 1786-1795, 1999.
17. Macefield VG, Fuglevand AJ, and Bigland-Ritchie B. Contractile properties of single motor units in human toe extensors assessed by intraneural motor axon stimulation. J Neurophysiol 75: 2509-2519, 1996.
18. McAuley JH, Rothwell JC, and Marsden CD. Frequency peaks of tremor, muscle vibration and electromyographic activity at 10 Hz, 20 Hz and 40 Hz during human finger muscle contraction may reflect rhythmicities of central neural firing. Exp Brain Res 114: 525-541, 1997.
19. Murthy VN and Fetz EE. Oscillatory activity in sensorimotor cortex of awake monkeys: synchronization of local field potentials and relation to behavior. J Neurophysiol 76: 3949-3967, 1996.
20. Patten C and Kamen G. Adaptations in motor unit discharge activity with force control training in young and older human adults. Eur J Appl Physiol 83: 128-143, 2000.
21. Perreault EJ, Day SJ, Hulliger M, Heckman CJ, and Sandercock TG. Summation of forces from multiple motor units in the cat soleus muscle. J Neurophysiol 89: 738-744, 2003.
22. Person RS and Kudina LP. Discharge frequency and discharge pattern of human motor units during voluntary contraction of muscle. Electroenceph Clin Neurophysiol 32: 471-483, 1972.
23. Powers RK and Binder MD. Summation of motor unit tensions in the tibialis anterior muscle of the cat under isometric and nonisometric conditions. J Neurophysiol 66: 1838-1846, 1991.
24. Sears TA and Stagg D. Short-term synchronization of intercostal motoneurone activity. J Physiol 263: 357-381, 1976.
25. Semmler JG. Motor unit synchronization and neuromuscular performance. Exerc Sport Sci Rev 30: 8-14, 2002.
26. Semmler JG, Kornatz KW, Kern DS, and Enoka RM. Motor unit synchronization reduces the steadiness of anisometric contractions by a hand muscle. Soc Neurosci Abstr 27: 168.3, 2001.
27. Semmler JG, Steege JW, Kornatz KW, and Enoka RM. Motor-unit synchronization is not responsible for larger motor-unit forces in old adults. J Neurophysiol 84: 358-366, 2000.
28. Slifkin AB and Newell KM. Noise, information transmission, and force variability. J Exp Psychol 25: 837-851, 1999.
29. Slifkin AB, Vaillancourt DE, and Newell KM. Intermittency in the control of continuous force production. J Neurophysiol 84: 1708-1718, 2000.
30. Taylor AM and Enoka RM. Model motor neurons with active dendrites require more input synchrony than passive models for the same level of motor unit synchrony. Soc Neurosci Abstr 28: 856.11, 2002.
31. Taylor AM, Steege JW, and Enoka RM. Increased variability of motor unit discharge rate decreases the steadiness of simulated isometric contractions (Abstract). Physiologist 43: 321, 2000.
32. Taylor AM, Steege JW, and Enoka RM. Motor-unit synchronization alters spike-triggered average force in simulated contractions. J Neurophysiol 88: 265-276, 2002.
33. Thomas CK, Bigland-Ritchie B, and Johansson RS. Force-frequency relationships of human thenar motor units. J Neurophysiol 65: 1509-1516, 1991.
34. Vaillancourt DE, Larsson L, and Newell KM. Time-dependent structure in the discharge rate of human motor units. Clin Neurophysiol 113: 1325-1338, 2002.
35. Vaillancourt DE and Newell KM. Aging and the time and frequency structure of force output variability. J Appl Physiol 94: 903-912, 2003.
36. Yao W, Fuglevand AJ, and Enoka RM. Motor-unit synchronization increases EMG amplitude and decreases force steadiness of simulated contractions. J Neurophysiol 83: 441-452, 2000.
37. Zijdewind I, Zwarts MJ, and Kernell D. Fatigue-associated changes in the electromyogram of the human first dorsal interosseous muscle. Muscle Nerve 22: 1432-1436, 1999.