Abstract
Motor-unit behaviour is central to understanding muscle contractile function. Commonly, in vivo experimental measurements of motor-unit twitches are taken at points biomechanically linked to the muscle. Here, we investigate whether these measurements accurately represent muscle twitch force behaviour by using a 3D, continuum-mechanical masticatory system model. Selected motor-units within the masseters were individually stimulated, and twitch force measured at the occlusal surface (typical for experiments) and at the muscle origin (representing true twitch force). Occlusal measurements underpredicted twitch force across all motor-units. This was due to force (re)distribution caused by motor-unit location and muscle architecture. Additionally, we investigated the assumption of twitch force summation by comparing twitch forces from co-contracting motor-units with linearly summed counterparts. Shear stress comparisons within the muscle revealed a lower lateral force dispersion for the co-contracting case, partly explaining the underpredicted magnitudes of the linearly summed forces. These findings have implications for twitch force characterisation and motor-unit based muscle modelling.
Access this chapter
Tax calculation will be finalised at checkout
Purchases are for personal use only
Similar content being viewed by others
References
Adrian, E.D., Bronk, D.W.: The discharge of impulses in motor nerve fibres: Part II. The frequency of discharge in reflex and voluntary contractions. J. Physiol. 67(2), 9–151 (1929). https://doi.org/10.1113/jphysiol.1929.sp002557
Dideriksen, J.L., Negro, F.: Spike-triggered averaging provides inaccurate estimates of motor unit twitch properties under optimal conditions. J. Electromyogr. Kinesiol. 43, 104–110 (2018). https://doi.org/10.1016/j.jelekin.2018.09.008
Clark, R.W., Luschei, E.S., Hoffman, D.S.: Recruitment order, contractile characteristics, and firing patterns of motor units in the temporalis muscle of monkeys. Exp. Neurol. 61(1), 31–52 (1978). https://doi.org/10.1016/0014-4886(78)90179-6
Fuglevand, A.J., Winter, D.A., Patla, A.E.: Models of recruitment and rate coding organization in motor-unit pools. J. Neurophysiol. 70(6), 2470–2488 (1993). https://doi.org/10.1152/jn.1993.70.6.2470
Heidlauf, T., Klotz, T., Rode, C., Siebert, T., Röhrle, O.: A continuum-mechanical skeletal muscle model including actin-titin interaction predicts stable contractions on the descending limb of the force-length relation. PLOS Comput. Biol. 13(10), e1005773 (2017). https://doi.org/10.1371/journal.pcbi.1005773
Henneman, E.: Relation between size of neurons and their susceptibility to discharge. Science 126(3287), 1345–1347 (1957)
McMillan, A.S., Sasaki, K., Hannam, A.G.: The estimation of motor unit twitch tensions in the human masseter muscle by spike-triggered averaging. Muscle Nerve 13(8), 697–703 (1990). https://doi.org/10.1002/mus.880130806
Negro, F., Yavuz, U.Ş., Farina, D.: Limitations of the spike-triggered averaging for estimating motor unit twitch force: a theoretical analysis. PLOS ONE 9(3), e92390 (2014). https://doi.org/10.1371/journal.pone.0092390
Negro, F., Orizio, C.: Robust estimation of average twitch contraction forces of populations of motor units in humans. J. Electromyogr. Kinesiol. 37, 132–140 (2017). https://doi.org/10.1016/j.jelekin.2017.10.005
Powers, R.K., Binder, M.D.: Summation of motor unit tensions in the tibialis posterior muscle of the cat under isometric and nonisometric conditions. J. Neurophysiol. 66(6), 1838–1846 (1991). https://doi.org/10.1152/jn.1991.66.6.1838
Purslow, P.P.: Muscle fascia and force transmission. J. Bodywork Mov. Ther. 14(4), 411–417 (2010). https://doi.org/10.1016/j.jbmt.2010.01.005
Roatta, S., Arendt-Nielsen, L., Farina, D.: Sympathetic-induced changes in discharge rate and spike-triggered average twitch torque of low-threshold motor units in humans. J. Physiol. 586(22), 5561–5574 (2008). https://doi.org/10.1113/jphysiol.2008.160770
Röhrle, O., Sprenger, M., Schmitt, S.: A two-muscle, continuum-mechanical forward simulation of the upper limb. Biomech. Modeling Mechanobiol. 16(3), 743–762 (2016). https://doi.org/10.1007/s10237-016-0850-x
Röhrle, O., Saini, H., Lee, P.V.S., Ackland, D.C.: A novel computational method to determine subject-specific bite force and occlusal loading during mastication. Comput. Methods Biomech. Biomed. Eng. 21(6), 453–460 (2018). https://doi.org/10.1080/10255842.2018.1479744
Röhrle, O., Yavuz, U.Ş., Klotz, T., Negro, F., Heidlauf, T.: Multiscale modeling of the neuromuscular system: coupling neurophysiology and skeletal muscle mechanics. Wiley Interdisc. Rev. Syst. Biol. Med. 11(6), e1457 (2019). https://doi.org/10.1002/wsbm.1457
Saini, H., Ackland, D.C., Gong, L., Cheng, Röhrle, O.: Occlusal load modelling significantly impacts the predicted tooth stress response during biting: a simulation study. Comput. Methods Biomech. Biomed. Eng. 23(7), 261–270. https://doi.org/10.1080/10255842.2020.1711886
Saini, H., Klotz, T., Röhrle, O.: Enriching macroscopic skeletal muscle models on a motor-unit level reveals differences in joint force: a simulation study (in Preparation)
Saini, H., Röhrle, O.: A biophysically guided constitutive law of the musculotendon-complex: modelling and numerical implementation in Abaqus (2021). https://papers.ssrn.com/sol3/papers.cfm?abstract_id=4102677
Sherrington, C.S.: Ferrier lecture.-some functional problems attaching to convergence. Proc. Roy. Soc. London B Biolog. Sci. 105(737), 332–362 (1929). https://doi.org/10.1098/rspb.1929.0047
Stein, R.B., French, A.S., Mannard, A., Yemm, R.: New methods for analysing motor function in man and animals. Brain Res. 40(1), 187–192 (1972). https://doi.org/10.1016/0006-8993(72)90126--6
Taylor, A.M., Steege, J.W., Enoka, R.M.: Motor-unit synchronization alters spike-triggered average force in simulated contractions. J. Neurophysiol. 88(1), 265–276 (2002). https://doi.org/10.1152/jn.2002.88.1.265
Troiani, D., Filippi, G.M., Bassi, F.A.: Nonlinear tension summation of different combinations of motor units in the anesthetized cat peroneus longus muscle. J. Neurophysiol. 81(2), 771–780 (1999). https://doi.org/10.1152/jn.1999.81.2.771
Yemm, R.: The orderly recruitment of motor units of the masseter and temporal muscles during voluntary isometric contraction in man. J. Physiol. 265(1), 163–174 (1977). https://doi.org/10.1113/jphysiol.1977.sp011710
Author information
Authors and Affiliations
Corresponding author
Editor information
Editors and Affiliations
Rights and permissions
Copyright information
© 2023 The Author(s), under exclusive license to Springer Nature Switzerland AG
About this paper
Cite this paper
Saini, H., Röhrle, O. (2023). Simulation Study to Investigate the Accuracy of in Vivo Motor-Unit Twitch Force Measurements. In: Tavares, J.M.R.S., Bourauel, C., Geris, L., Vander Slote, J. (eds) Computer Methods, Imaging and Visualization in Biomechanics and Biomedical Engineering II. CMBBE 2021. Lecture Notes in Computational Vision and Biomechanics, vol 38. Springer, Cham. https://doi.org/10.1007/978-3-031-10015-4_20
Download citation
DOI: https://doi.org/10.1007/978-3-031-10015-4_20
Published:
Publisher Name: Springer, Cham
Print ISBN: 978-3-031-10014-7
Online ISBN: 978-3-031-10015-4
eBook Packages: EngineeringEngineering (R0)