Experimentally verified mathematical approach for the prediction of force developed by motor units at variable frequency stimulation patterns

Raikova, Rositsa; Rusev, Rostislav; Drzymała‐Celichowska, Hanna; Krutki, Piotr; Aladjov, Hristo; Celichowski, Jan

doi:10.1016/j.jbiomech.2010.01.034

Cited by 12 publications

(20 citation statements)

References 32 publications

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“…The experimental procedures were described in detail in previous papers Raikova et al 2007bRaikova et al , 2010. Briefly, initial surgical preparation concerned left sciatic nerve and MG muscle isolation and denervation of all muscles of the hindlimb except the one studied.…”

Section: Methodsmentioning

confidence: 99%

“…When the force curve developed by (i Ϫ 1) pulses is mathematically subtracted from that developed by i pulses, the ith supplement of force (the ith contraction) is calculated. It was shown that these contractions had twitchlike forms (MacIntosh et al 2007;Raikova et al 2008;Stein and Parmiggiani 1981). For an analytical description of these twitch-form curves, a six-parameter analytical function was proposed and tested in several series of experiments to prove its ability to describe precisely all twitch forms .…”

Section: Methodsmentioning

confidence: 99%

“…Moreover, a progressive increase in force and time parameters of the decomposed twitches was observed in parallel to a tetanus force increase. It should be stressed that the above-mentioned studies involved muscle or MU forces evoked by constant stimulation frequencies, which are not observed during voluntary activity.In our previous papers we have studied MU contractions evoked by trains of pulses at variable interpulse intervals (IPIs), more closely resembling physiological conditions Krutki et al 2008;Raikova et al 2010). A new mathematical algorithm for decomposition of a MU tetanic force into a series of twitch responses has been proposed.…”

mentioning

confidence: 99%

“…In our previous papers we have studied MU contractions evoked by trains of pulses at variable interpulse intervals (IPIs), more closely resembling physiological conditions Krutki et al 2008;Raikova et al 2010). A new mathematical algorithm for decomposition of a MU tetanic force into a series of twitch responses has been proposed.…”

mentioning

confidence: 99%

“…These studies have revealed for a small sample of slow and fast MUs significant correlations between the parameters of the successive decomposed twitches and the initial force level at which the next contraction starts. However, these studies have been limited to fast units only or restricted to a few MUs, selected only to illustrate methods proposed in the paper (Raikova et al 2010). Because of the inconsistent behavior of this small group of units, no common rules with respect to particular MU types could be derived.…”

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Dynamic changes of twitchlike responses to successive stimuli studied by decomposition of motor unit tetanic contractions in rat medial gastrocnemius

Celichowski

Raikova

Aladjov

et al. 2014

Journal of Neurophysiology

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Celichowski J, Raikova R, Aladjov H, Krutki P. Dynamic changes of twitchlike responses to successive stimuli studied by decomposition of motor unit tetanic contractions in rat medial gastrocnemius. J Neurophysiol 112: 3116 -3124, 2014. First published September 24, 2014 doi:10.1152/jn.00895.2013.-Unfused tetanic contractions evoked by trains of stimuli at variable interpulse intervals (IPIs) were recorded for 10 fast fatigable (FF), 10 fast resistant (FR), and 10 slow (S) motor units (MUs) and subsequently decomposed with a mathematical algorithm into trains of twitch-shape responses to successive stimuli. The mean stimulation frequencies were matched for each MU to evoke tetani of similar fusion degrees, whereas the variability range of IPIs was in each case 50 -150% of the mean IPI. Force and time parameters of decomposed twitches were analyzed and related to the first response. Considerable variability of the analyzed twitch parameters was observed in each MU, although the largest range of variability occurred in slow MUs. In general, the decomposed twitch responses had longer duration and higher force than single-twitch contractions, although for nine FF and six FR MUs some of the decomposed responses were slightly weaker (but not faster) than the first twitches of these MUs. Comparison of the strongest decomposed twitch to the first decomposed twitch revealed ratios of forces up to 2.35, 3.33, and 6.89 for FF, FR, and S MUs and ratios of force-time areas up to 3.54, 4.67, and 14.26 for FF, FR, and S MUs, whereas for the contraction times the ratios of the longest decomposed twitch to the first twitch amounted to 2.46, 2.07, and 3.52 for FF, FR, and S MUs, respectively. The results indicate that contractile responses to successive action potentials are considerably variable, especially for slow MUs. motor unit; force development; random stimulation pattern; twitch THE FORCE OF A SKELETAL MUSCLE is a result of summation of forces generated by numerous coactive motor units (MUs) and mechanical activity of each MU evoked by trains of action potentials generated by a motoneuron at variable time intervals (Adam et al. 1998;Boe et al. 2005;Masuda and De Luca 1991;Moritz et al. 2005;Westergaard and De Luca 2011). In general, successive MU action potentials recorded in a muscle are quite stable in amplitude and shape (Mambrito and De Luca 1983;Stålberg 2003), although small changes in duration and amplitude of MU action potentials, related to a decrease in muscle fiber conduction velocity, were also reported during 30 s of voluntary activity (Farina and Falla 2007). Contrary to this, the twitchlike responses to successive motoneuronal action potentials within a tetanic contraction are highly variable, as reported in several studies on cat Parmiggiani 1979, 1981) and rat (MacIntosh et al. 2007) muscles. These studies have shown that the amplitude of a single muscle twitch may be significantly smaller than a twitchlike response to one of the stimuli within a train. When the same method was used for tetanic contrac...

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Dynamic changes of twitchlike responses to successive stimuli studied by decomposition of motor unit tetanic contractions in rat medial gastrocnemius

Celichowski

Raikova

Aladjov

et al. 2014

Journal of Neurophysiology

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The tetanic depression in fast motor units of mammalian skeletal muscle can be evoked by lengthening of one initial interpulse interval

et al. 2011

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A lower than expected tetanic force (the tetanic depression) is regularly observed in fast motor units (MUs) when a higher stimulation frequency immediately follows a lower one. The aim of the present study was to determine whether prolongation of only the first interpulse interval (IPI) resulted in tetanic depression. The experiments were carried out on fast MUs of the medial gastrocnemius muscle in cats and rats. The tetanic depression was measured in each case as the force decrease of a tetanus with one IPI prolonged in relation to the tetanic force at the respective constant stimulation frequency. Force depression was observed in all cases studied and was considerably greater in cats. For cats, the mean values of force depression amounted to 28.64% for FR and 10.86% for FF MUs whereas for rats 9.30 and 7.21% for FR and FF motor units, respectively. Since the phenomenon of tetanic depression in mammalian muscle is commonly observed even after a change in only the initial interpulse interval within a stimulation pattern, it can effectively influence processes of force regulation during voluntary activity of a muscle, when motoneurones progressively increase the firing rate.

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Muscle fibers and their synapses differentially adapt to aging and endurance training

Deschenes

Adan

et al. 2018

Experimental Gerontology

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Experimentally verified mathematical approach for the prediction of force developed by motor units at variable frequency stimulation patterns

Cited by 12 publications

References 32 publications

Dynamic changes of twitchlike responses to successive stimuli studied by decomposition of motor unit tetanic contractions in rat medial gastrocnemius

Dynamic changes of twitchlike responses to successive stimuli studied by decomposition of motor unit tetanic contractions in rat medial gastrocnemius

The tetanic depression in fast motor units of mammalian skeletal muscle can be evoked by lengthening of one initial interpulse interval

Muscle fibers and their synapses differentially adapt to aging and endurance training

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