Assessment of human motor unit twitches — a comparison of spike-triggered averaging and intramuscular microstimulation

A Simulation Study to Examine the Effect of Common Motoneuron Inputs on Correlated Patterns of Motor Unit Discharge

“…Values for motor unit twitch force reported during intraneural motor axon stimulation range from 2.2-72.8 mN and twitch contraction times from 32.0-111.3 ms (McNulty et al, 2000). Similar twitch force and contraction times, 1-75 mN and 42-76 ms respectively, were reported by Gossen et al (2003) using spiketriggered averaging of motor unit twitch force in the FDI and in earlier studies (Milner-Brown et al, 1973;Kossev et al, 1994;Carpentier et al, 2001). Based on these experimental data, motor unit twitch force was assigned to increase exponentially from 1.04-80.00 mN between motor unit 1 and 100, while twitch contraction time decreased exponentially from 89.07-31.71 ms, Table 2.…”

Simulation of the motor units control during a fast elbow flexion in the sagittal plane

“…Lacking information about both the composition of the living human muscles from different MUs [3] and about the characteristics of their twitches in vivo, we only tested the hypothesis of some authors [19] that the twitch parameters of different MUs are distributed continuously. The contraction times and half-relaxation times reported for some human hand muscles [4,7,9,21] are widely dis- tributed among average values. Our parameters (Table 1) fitted well with these average values.…”

Human motor units in health and disease

“…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.…”

“…[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.…”

“…9,12,18,19,22,23,26,[28][29][30][31][32][33][34][35][36][37] Furthermore, the contractile properties of single MUs in other human muscles derived with a variety of techniques are surprisingly very similar to those for the thenar muscles.…”