Isometric voluntary force production and relaxation capacity of the quadriceps femoris (QF) muscle was compared between 12 children with spastic diplegic cerebral palsy (CP) and healthy controls, age 10-11 years. Children with CP had less (p < .05) maximal voluntary-contraction force, voluntary activation, and rate of force development than controls. Visual reaction to contraction did not diffe...

We investigated whether altered peripheral and/or corticospinal excitatory output and voluntary activation are implicated in hypohydration-induced reductions in muscle isometric and isokinetic (90°.s(-1)) strength. Nine male athletes completed two trials (hypohydrated, euhydrated) comprising 90 min cycling at 40°C, with body weight losses replaced in euhydrated trial. Peripheral nerve and trans...

[Purpose] This study aimed to determine the effect of varying hip flexion angle on hip muscle activity during isometric contraction in abduction. [Subjects] Twenty-seven healthy men (mean age=21.5 years, SD=1.2) participated in this study. [Methods] Surface electromyography (EMG) was recorded of the upper portion of the gluteus maximus (UGM), lower portion of the gluteus maximus (LGM), tensor f...

The aim of this study was to determine the applicability and reliability of a transcranial magnetic stimulation twitch interpolation technique for measuring voluntary activation of a lower limb muscle group. Cortical voluntary activation of the knee extensors was determined in nine healthy men on two separate visits by measuring superimposed twitch torques evoked by transcranial magnetic stimul...

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...

The aim of the present study was to determine the effects of voluntary breathing on corticospinal excitability of a leg muscle during isometric contraction. Seven subjects performed 5-s isometric knee extension at the intensity of 10% of maximal voluntary contraction (10% MVC). During the 10% MVC, the subjects were instructed to breath normally (NORM) or to inhale (IN) or exhale (OUT) once as f...

BACKGROUND Peripheral muscle dysfunction is a common finding in patients with COPD; however, the structural adaptation and functional impairment of the upper and lower limb muscles do not seem to be homogenous. We compared muscle fatigue and recovery time between 2 representative muscles: the middle deltoid and the quadriceps femoris. METHODS Twenty-one subjects with COPD (FEV1 46.1 ± 10.3% o...

QUESTION Can real-time visual feedback facilitate the activity of serratus anterior in individuals with scapular winging during shoulder flexion? DESIGN Comparative, repeated-measures experimental study. PARTICIPANTS Nineteen subjects with scapular winging. INTERVENTION Participants performed isometric shoulder flexion at 60° and 90° with and without real-time visual feedback using a vide...