This paper considers an experiments on co-contraction of antagonist muscles of human limb using RISE (robust integral of the sign of the error) control. It is known that some experimental results show that the antagonist muscle and agonist muscle work at the same time, then it is called co-contraction. However, the control method of the antagonist muscle in order to give the electrical impulses...

A fundamental feature of pennate muscles is that muscle fibers are oriented at an angle to the line of action and rotate as they shorten, becoming more oblique throughout a contraction. This change in fiber orientation (pennation angle) can amplify the shortening velocity of a fiber and increase output velocity of the muscle. The velocity advantage resulting from dynamic changes in pennation an...

ARTS, THEO, PIETER C. VEENSTRA, AND ROBERT S. RENEMAN. Epicardial deformation and left ventricular walL mechanics during ejection in the dog. Am. J. Physiol. 243 (Heart Circ. Phvsiol. 12): H379-H390, 1982.-Significant differences between kpicardial and endocardial systolic stress in the wall of the left ventricle (LV) have been predicted by various models of LV mechanics. Yet a model incorporat...

CONTEXT Anismus is a prevalent functional cause of outlet delay. It is characterized by symptoms of obstructed defecation associated with paradoxical contraction of the pelvic floor muscles. OBJECTIVE To evaluate the ability of two dimensional anal ultrasonography to identify anismus patients with paradoxical contraction or normal relaxation, comparing findings with manometric measurements. ...

1. The effects of maximum voluntary eccentric muscle actions on forearm flexor strength were studied at three different elbow joint angles (0.87, 1.57 and 2.79 rad) to examine whether subsequent impairment of contractile function is muscle length-specific. 2. A bout of 70 maximum voluntary eccentric muscle actions performed with the forearm flexors elicited delayed muscle soreness, efflux of cr...

Studies using animal models have been unable to determine the mechanical stimuli that most influence muscle architectural adaptation. We examined the influence of contraction mode on muscle architectural change in humans, while also describing the time course of its adaptation through training and detraining. Twenty-one men and women performed slow-speed (30 degrees /s) concentric-only (Con) or...

background: the purpose of this study was to investigate the ratio of electromyography (em g) activities of the vastus medialis obliqus (vmo) and vastus lateralis (vl) within seven angles of knee joint range of motion using isometric contraction in open kinetic chain (ok c) and closed kinetic chain (ckc). methods: the dominant knees of 44 healthy female subjects (mean age: 24.84 with range: 20-...

BACKGROUND AND PURPOSE Slumped sitting is known to increase disc pressure and aggravate chronic low back pain. In addition, it has been recognized that co-contraction of the deep spine-stabilizing muscles enhances lumbar segmental stability and the sacro-iliac joint. The purpose of this study was to compare the electromyographic (EMG) activity of the trunk muscles and the muscle thickness of th...

The purpose of this paper is to study the dynamics of a square billiard with a non-standard reflection law such that the angle of reflection of the particle is a linear contraction of the angle of incidence. We present numerical and analytical arguments that the nonwandering set of this billiard decomposes into three invariant sets, a parabolic attractor, a chaotic attractor, and a set consisti...

The aim of the present study was to investigate the behavior of human muscle fascicles during dynamic contractions. Eight subjects performed maximal isometric dorsiflexion contractions at six ankle joint angles and maximal isokinetic concentric and eccentric contractions at five angular velocities. Tibialis anterior muscle architecture was measured in vivo by use of B-mode ultrasonography. Duri...