Co-contraction of abdominal muscles (abdominal bracing) is considered an effective exercise technique for improving spinal stability, and is often recommended and/or included in rehabilitation and/or fitness programs (Maeo et al., 2013b). Abdominal bracing has been shown to induce higher activation in deep abdominal muscles such as transversus abdominis and internal oblique muscles, which are c...

It is unclear during human aging whether healthy older adults (>70 yr old) experience greater, lesser, or the same fatigability compared with younger adults. The reported disparate findings may be related to the task-dependent nature of fatigue and the limited number of studies exploring nonisometric contractile function and aging. The purpose here was to determine the effects of fast shortenin...

Isometric contractions induced by neuromuscular electrostimulation (NMES) have been shown to result in a prolonged force decrease but the time course of the potential central and peripheral factors have never been investigated. This study examined the specific time course of central and peripheral factors after isometric NMES-induced muscle damage. Twenty-five young healthy men were subjected t...

The contributions of nervous system muscle activation and muscle atrophy to poststroke weakness have not been evaluated together in the same subject. Maximal voluntary contraction (MVC) torque, voluntary activation (twitch interpolation), and electromyographic (EMG) amplitude were determined bilaterally in the plantar flexors of seven chronic stroke survivors (40-63 yr, 24-51 mo poststroke). Vo...

Abstract Repetitive transcranial magnetic stimulation (rTMS) is commonly dosed using resting motor threshold (rMT), i.e., the minimal stimulator power needed to elicit a response in musculature. Many stroke survivors do not present with rMT, necessitating rTMS dosing during active contractions, or an (aMT). However, relationship between rMT and aMT post-stroke unknown. We conducted cross-sectio...

This study employed longitudinal measures of evoked spinal reflex responses (Hoffman reflex, V wave) to investigate changes in the activation of muscle and to determine if there are "linked" neural adaptations in the motor pathway following isometric resistance training. Twenty healthy, sedentary males were randomly assigned to either the trained (n = 10) or control group (n = 10). The training...

We tested the hypothesis that aging is associated with an impaired contraction-induced rapid vasodilation in healthy adults. We reasoned that employing single contractions of a small muscle mass would allow us to isolate the local rapid vasodilatory responses independent of systemic hemodynamic and sympathetic neural influences on forearm hemodynamics. We measured forearm blood flow (Doppler ul...

background: surface electromyography (semg) of muscles is a non-invasive tool that can be helpful in the assessment of muscle function and some motor control evaluations. a loss of force, known as muscle fatigue is accompanied by changes in muscle electrical activity. one of the most commonly used surface emg parameters which reflects paraspinal muscle fatigue during different tasks and positio...

The force enhancement of a twitch after a maximal conditioning muscle contraction [i.e., postactivation potentiation (PAP)] is reduced with aging, but its influence on the summation of force in response to repetitive stimulation at different frequencies is not known. The purpose of this work was to compare the electrically evoked mechanical responses of the tibialis anterior muscle between youn...

Transcranial magnetic (TMS) and motor point stimulation have been used to determine voluntary activation (VA). However, very few studies have directly compared the two stimulation techniques for assessing VA of the elbow flexors. The purpose of this study was to compare TMS and motor point stimulation for assessing VA in non-fatigued and fatigued elbow flexors. Participants performed a fatigue ...