performed the experiments and analysed the data. 14 Y.K. designed the study and wrote the manuscript together with T. ABSTRACT 25 Spindle Ia afferents may be differentially involved in voluntary isometric contraction, depending on 26 the pattern of synaptic connections in spindle reflex pathways. We investigated how isometric 27 contraction of masseter muscles is regulated through the activity ...

The aim of the present study was to test the hypothesis that the age-associated decrease of tendon stiffness would necessitate greater muscle fascicle strains to produce similar levels of force during isometric contraction. Greater fascicle strains could force sarcomeres to operate in less advantageous regions of their force-length and force-velocity relationships, thus impairing the capacity t...

Although evidence has been presented that, at low ionic strength, myosin heads in relaxed skeletal muscle fibers form linkages with actin filaments, the effect of low ionic strength on contraction characteristics of Ca(2+)-activated muscle fibers has not yet been studied in detail. To give information about the mechanism of muscle contraction, we have examined the effect of low ionic strength o...

Exposure to μG is known to induce a decrease in muscle strength in animals as well as in humans, principally in postural muscles (Edgerton & Roy, 1996). This is due to atrophy and induces mechanical adaptations affecting contractile (Thomason & Booth, 1990) and elastic properties (Canon & Goubel, 1995). Recently, changes in contractile and elastic properties of the human plantarflexors immediat...

Motor-unit synchronization, which is a measure of the near simultaneous discharge of action potentials by motor units, has the potential to influence spike-triggered average force and the steadiness of a low-force isometric contraction. The purpose of the study was to estimate the contribution of motor-unit synchronization to the larger spike-triggered average forces and the decreased steadines...

TO THE EDITOR: In their recent paper, Cornachione et al. (1) draw three major conclusions: 1) that cardiac myofibrils do not show static tension or residual force enhancement; 2) that static tension/residual force enhancement is directly related to titin isoforms; and 3) that static tension/residual force enhancement is not associated with titin-actin interactions. Here, I would like to point o...

The purpose of this study was to determine whether there are alterations in the dihydropyridine and/or ryanodine receptors that might explain the excitation-contraction uncoupling associated with eccentric contraction-induced skeletal muscle injury. The left anterior crural muscles (i.e., tibialis anterior, extensor digitorum longus, and extensor hallucis longus) of mice were injured in vivo by...