The activity of 18 motor units (MUs) of m. biceps brachii was studied in four adults during highamplitude isotorque ramp-and-hold movements in the elbow joint. The recorded MUs had low isometric thresholds (below 6% of maximal voluntary contraction). During the examined movement, MUs of group I responded to application of subthreshold loads by increases in their firing rates, MUs of group II reacted to suprathreshold loads by decreases in the attained activity level, and background firing of MUs of group III at application of suprathreshold loads did not change. Dependences between the joint angle and firing rate, as well as between the velocities of these parameters, were positive in group I MUs and negative in those of group II. A decrease in the firing rate of MUs during flexion movements is likely to be related to nonlinear effects during the torque generation by the elbow flexors due to the specificity of geometrical arrangement of MU fibers with respect to the joint.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
C. J. De Luca and P. Contessa, “Hierarchical control of motor units in voluntary contractions,” J. Neurophysiol., 107, 178-195 (2012).
C. J. De Luca and E. C. Hostage, “Relationship between firing rate and recruitment threshold of motoneurons in voluntary isometric contractions,” J. Neurophysiol., 104, 1034-1046 (2010).
S. J. Garland, J. D. Cooke, K. J. Miller, et al., “Motor unit activity during human single joint movements,” J. Neurophysiol., 76, 1982-1990 (1996).
A. N. Tal’nov, S. G. Serenko, S. S. Strafun, and A. I. Kostyukov, “Analysis of the electromyographic activity of human elbow joint muscles during slow linear flexion movements in isotorque conditions,” Neuroscience, 90, 1123-1136 (1999).
A. I. Kostyukov, “Muscle hysteresis and movement control: a theoretical study,” Neuroscience, 83, 303-320 (1998).
K. J. Miller, S. J. Garland, T. Ivanova, and T. Ohtsuki, “Motor-unit behavior in humans during fatiguing arm movements,” J. Neurophysiol., 75, 1629-1636 (1996).
A. Tax, J. J. Denier van der Gon, C. C. Gielen, and C. M. van den Tempel, “Differences in the activation of m. biceps brachii in the control of slow isotonic movements and isometric contractions,” Exp. Brain Res., 76, 55-63 (1989).
T. Ivanova, S. J. Garland, and K. J. Miller, “Motor unit recruitment and discharge behavior in movements and isometric contractions,” Muscle Nerve, 20, 867-874 (1997).
M. van Bolhuis, W. P. Medendorp, and C. C. Gielen, “Motor unit firing behavior in human arm flexor muscles during sinusoidal isometric contractions and movements,” Exp. Brain Res., 117, 120-130 (1997).
J. Duchateau and R. M. Enoka, “Neural control of shortening and lengthening contractions: influence of task constraints,” J. Physiol., 586, 5853-5864 (2008).
K. Akazawa and R. Okuno, “Firing behaviors of single motor units in m. biceps brachii during isovelocity elbow flexion,” Proceedings of the 10th International Conference on Biomedical Engineering, Singapore (2000), pp. 249-250.
I. Kostyukov, A. N. Tal’nov, S. G. Serenko, et al., “Control of the elbow extensor muscles in slow targeted extensions of the arm in humans,” Neirofiziologiya / Neurophysiology, 33, No. 1, 60-70 (2001).
M. Theeuwen, C. C. Gielen, and L. E. Miller, “The relative activation of muscles during isometric contractions and low-velocity movements against a load,” Exp. Brain Res., 101, 493-505 (1994).
V. Vereshchaka, A. V. Gorkovenko, V. I. Khorevin, et al., “Peculiarities of activation of the shoulder belt and shoulder muscles in generation of different-direction isometric efforts by the forearm,” Neirofiziologiya / Neurophysiology, 42, No. 4, 265-275 (2011).
A. V. Gorkovenko, S. Sawczyn, N. V. Bulgakova, et al., “Muscle agonist-antagonist interactions in an experimental joint model,” Exp. Brain Res., 222, 399-414 (2012).
P. V. Komi, V. Linnamo, P. Silventoinen, and M. Sillapää, “Force and EMG power spectrum during eccentric and concentric actions,” Med. Sci. Sports Exe., 32, 1757-1762 (2000).
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Tal’nov, A.N., Tomiak, T., Maznychenko, A.V. et al. Firing Patterns of Human Biceps Brachii Motor Units During Isotorque Ramp-and-Hold Movements in the Elbow Joint. Neurophysiology 46, 212–220 (2014). https://doi.org/10.1007/s11062-014-9431-8
Received:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s11062-014-9431-8