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...

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 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...

Background: The transverse abdominis (TrA) muscle is one of the most important muscles that contribute to the stability of the lumbar spine. Strengthening of trunk muscles that have a significant role in trunk stability is very important in the field of professional sport, sport medicine and rehabilitation of patient with low back pain (LBP). Identifying the exercises that can improve the stren...

Although activity of the rectus femoris (RF) differs from that of the other synergists in quadriceps femoris muscle group during physical activities in humans, it has been suggested that the activation pattern of the vastus intermedius (VI) is similar to that of the RF. The purpose of present study was to examine activation of the VI during isometric hip flexion. Ten healthy men performed isome...

The extents to which decreased muscle size or activation are responsible for the decrease in strength commonly observed with aging remain unclear. Our purpose was to compare muscle isometric strength [maximum voluntary contraction (MVC)], cross-sectional area (CSA), specific strength (MVC/CSA), and voluntary activation in the ankle dorsiflexor muscles of 24 young (32 +/- 1 yr) and 24 elderly (7...

Thomas, Melissa M., Stephen S. Cheung, Geoff C. Elder, and Gordon G. Sleivert. Voluntary muscle activation is impaired by core temperature rather than local muscle temperature. J Appl Physiol 100: 1361–1369, 2006. First published December 8, 2005; doi:10.1152/japplphysiol.00945.2005.—Fatigue during hyperthermia may be due in part to a failure of the central nervous system to fully activate the ...

background : previous studies have investigated different effects of muscle fatigue on body systems. however, there are no reports on the effect of fatigue protocol and its level on musculotendinous stiffness (mts) of the tricep-surae. this study was designed to compare the effects of 2 levels of submaximal fatigue contraction on mts of triceps-surae. methods: twenty female students by simple r...