The effect of summation of contraction on acceleration signals in human skeletal muscle.

The purpose of this study was to determine the effects of summation of contraction on acceleration signals in human skeletal muscle. The torque parameters of dorsiflexion and acceleration signals in the tibialis anterior muscle were measured during evoked isometric contractions. In an examination of two-pulse trains with different inter-pulse intervals, the torque and accelerometer responses to inter-pulse intervals of 10-100 ms were recorded.

Changes in force and tendinous tissue elongation during the early phase of tetanic summation in in vivo human tibialis anterior muscle.

The purpose of this study was to determine the changes that occur in tendinous tissue properties during the early phase of tetanic summation in the in vivo human tibialis anterior muscle (TA). The torque response and tendinous tissue elongation following single stimuli, two-pulse trains, and three-pulse trains were recorded in the TA during isometric contractions. The elongation, compliance, and lengthening velocity of tendinous tissue were determined by real-time ultrasonography.

The effects of muscle architectural change with a pre-motion silent period on the subsequent muscular output during rapid voluntary movement.

This study aimed to determine the characteristics of the in vivo behaviour of human muscle architecture during a pre-motion silent period (PMSP) using ultrasonography. Subjects were requested to perform rapid knee extension with vertical jumping. Electromyographic signals were recorded from the vastus lateralis (VL), vastus medialis, and biceps femoris muscles.

Orthostatic influence on heart rate and blood pressure variability in trained persons with tetraplegia.

To examine the orthostatic influence on heart rate and blood pressure variability in persons with tetraplegia playing wheelchair basketball, ten trained persons with tetraplegia, ten untrained persons with tetraplegia, and ten able-bodied participated in this study. Spectrum analysis of the ECG R-R interval and blood-pressure on a beat-by-beat basis during head-up tilt 60 degrees sitting were performed. The ratio of the high frequency to total frequency (HF/TF) in the R-R interval decreased from supine (0.

In vivo behaviour of human muscle architecture and mechanomyographic response using the interpolated twitch technique.

This study investigated the origin of curvilinear change in the superimposed mechanomyogram (MMG) amplitude of the human medial gastrocnemius muscle (MG) with increasing contraction intensity. The superimposed twitch amplitude, the superimposed MMG amplitude and the extent of fascicle shortening were measured using ultrasonic images of electrical stimulation during isometric plantar flexions at levels 20%, 40%, 60%, 80%, and 100% of the maximal voluntary contraction (MVC). The superimposed twitch amplitude, the superimposed MMG amplitude and the extent of fascicle shortening decreased with increasing contraction intensity.

The effect of postactivation potentiation on the mechanomyogram.

To examine whether postactivation potentiation (PAP) was related to changes in the electromyogram (EMG) and in the mechanomyogram (MMG), evoked twitch torque properties were compared before and after a 10 s plantar flexion MVC in ten male subjects. Peak twitch torque (Pt), and the peak acceleration of the twitch torque development (d2T/dt2) were measured from electrical tibial nerve stimulation. In addition, from the medial gastrocnemius muscle, peak to peak MMG (p-p MMG) by means of accelerometer, and peak to peak EMG (M-wave) amplitudes were recorded.

Age comparison of H-reflex modulation with the Jendrássik maneuver and postural complexity.

Objective: The purpose of this study was to examine modulation of the soleus Hoffmann (H)-reflex in response to the Jendrássik maneuver (JM) in standing positions in young and elderly subjects.

Methods: Seventeen elderly (mean age=72.0 years) and 23 young (mean age=23.

Cortical and spinal motor excitability during the premovement EMG silent period prior to rapid voluntary movement in humans.

(1) To delineate the cortical and spinal excitability during the pre-movement silent period (PMSP), the motor-evoked potentials (MEPs) and H-reflexes were measured for 0-150 ms prior to rapid voluntary movements of 11 healthy subjects. The appearance of PMSP was judged from the electromyogram of the agonist muscle at each rapid movement and the differences of MEPs or H-reflex between the movement which PMSP appeared (PMSP MEPs or PMSP H-reflex) and the movement which did not appear (non-PMSP MEPs or non-PMSP H-reflex) were compared. (2) The mean amplitudes of the PMSP MEPs in the flexor carpi radialis were significantly smaller than the non-PMSP MEPs, whereas the mean amplitude of the PMSP H-reflex was not significantly different from the non-PMSP H-reflex.

Age-related changes in the interactive mobility of the hip and knee joints: a geometrical analysis.

This study examined any systematic age-related change in the passive range of motion (PROM) of the hip and knee joints. Seventy-seven healthy male volunteers ranging in age from 15 to 73 years were assessed. A geometrical range of motion (ROM) analysis was applied, which could evaluate the effects of both monoarticular and biarticular muscles.

A kinematic study of the upper-limb motion of wheelchair basketball shooting in tetraplegic adults.

Kinematic aspects of the reduced shooting ability of tetraplegic (TP) wheelchair basketball players were investigated and compared with those of able-bodied (AB) basketball players. TP showed significantly smaller values for the vertical component of ball release velocity (4.26 (degree/s) versus 5.