Parameters of human motor unit twitches obtained by intramuscular microstimulation

Elek, J.; Kossev, A; Dengler, Reinhard; Schubert, Margot; Wohlfahrt, Kai; Wolf, W.

doi:10.1016/0960-8966(92)90058-e

Cited by 37 publications

(46 citation statements)

References 21 publications

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“…Among the different contractile parameters, the twitch tension is the easiest to obtain and data on this parameter have been reported for the first dorsal interosseous, abductor digiti minimi, extensor digitorum communis, extensor carpi radialis extensor carpi ulnaris, and the median‐innervated thenar muscles 8, 15, 20, 26, 31, 47, 56, 58, 59, 63, 75, 78, 82, 83, 90, 95. All reported contractile properties in the upper limb muscles are compiled in Tables 2–4 and the general findings are summarized in the following sections.…”

Section: Findings In Different Human Musclesmentioning

confidence: 99%

Contractile properties of human motor units in health, aging, and disease

2001

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The primary function of skeletal muscle is to produce force for postural control and movement. Although the contractile properties of the whole muscle are useful functional indicators, they do not accurately reflect the heterogeneity of the constituent motor units (MUs) and their changes in health and disease. However, data on the contractile properties of human MUs, in comparison to other animal species, are relatively sparse. This, in part, is due to greater methodological challenges of in vivo studies of MUs in the human. The purpose of this review is to critically appraise the methods used in humans; to describe the normative data from different muscle groups; to discuss differences between data from healthy humans and other animal species; and, last, to characterize changes of the MU contractile properties in aging, disease, and in response to intervention. Because the spike-triggered averaging technique can only be used to study the twitch properties, other methods were subsequently developed to measure a wider range of contractile properties. Although there is general agreement between human data and those from other animal species, major differences do exist. Potential reasons for these discrepancies include true biological differences, but differences in the techniques used may also be responsible. Although limited, measurement of MU contractile properties in humans has provided insight into the changes associated with aging and motoneuronal diseases and provides a means of gauging their adaptive capacity for training and immobilization.

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Section: Findings In Different Human Musclesmentioning

confidence: 99%

Contractile properties of human motor units in health, aging, and disease

2001

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“…For example, the negative correlation between twitch force and contrac- tion time found in cats has not been seen across a variety of human motor units. 12,13,23,29,32,35,36 Also, "sag" has been used to discriminate between type S and type F motor units in cat muscles, but has not been observed in human toe extensor 23 or thenar motor units, 35 although it has been observed in the first dorsal interosseous muscle. 36 Zengel et al 37 reported 98% discrimination accuracy in predicting type S or F motor units based on the motoneuron AHP half-decay time.…”

Section: Discussionmentioning

confidence: 99%

Ischemia sensitivity and motoneuron afterhyperpolarization in human motor units

2004

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The purpose of this study was to examine whether motor units, grouped by speed of contraction in the human first dorsal interosseous muscle, differed in their sensitivity to ischemia and motoneuron afterhyperpolarization (AHP) time-course. Motor units were recorded while subjects held an abduction force for approximately 10 min. Subsequently, subjects abducted for 4-5 min under ischemic conditions. Motor unit twitches derived using spike-triggered averaging were allocated into "fast" or "slow" contracting groups based on twitch time to peak (TTP) force. Motor units in the "slow" group had a greater sensitivity to ischemia than the "fast" group. When upper and lower quartiles of TTP were compared, motor units with slow TTP had long AHP time-constants (as estimated by an interspike interval histogram transform). Thus, motor units grouped by speed of contraction differed in both their sensitivity to ischemia and motoneuron AHP time-course. This provides preliminary evidence that the estimated AHP time-constant may be used to deduce motor-unit type in humans.

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“…18,19,22,28,29,36,37 The latter two approaches involve the stimulation of single motor axons through a needle electrode inserted either into the nerve trunk or the muscle. Of the three approaches for stimulating single motor axons, surface stimulation is the least invasive and the best suited to clinical applications such as estimating the numbers of MUs within a muscle, studying neuromuscular transmission, and assessing the contractile properties of single MUs.…”

Section: Methods For Electrically Stimulating Single Motor Nerve Fibersmentioning

confidence: 99%

“…[7][8][9][10][11][12]18,19,22,23,26,28,[29][30][31][32][33][34][35][36][37] Such small forces are well exceeded, in most instances, by the forces imparted to the limb muscles by each beat of the heart and breath. Therefore, accurate measurements of the contractile speeds and forces produced by single MUs requires some means for stabilizing the limb and mechanically isolating the action of the muscle under study.…”

Section: Measurement Of the Contractile Properties Of Single Motor Unitsmentioning

confidence: 99%