[Purpose] The present study examined the effects of knee flexion angle on hip extensor muscle activity. [Subjects and Methods] Twenty healthy subjects maintained knee flexion angles of 0°, 30°, 60°, 90° and 110° in the prone position and performed maximal voluntary contraction in hip extension. Maximum torque in hip extension at the different angles was measured, and surface electromyogram acti...

Afferent input caused by electrical stimulation of a peripheral nerve increases corticospinal excitability during voluntary contractions, indicating that proprioceptive sensory input arriving at the cortex plays a fundamental role in modulating corticospinal excitability. The purpose of this study was to investigate whether the effect of electrical stimulation on the corticospinal excitability ...

It has been observed consistently and is well accepted that the steady-state isometric force after active muscle stretch is greater than the corresponding isometric force for electrically stimulated muscles and maximal voluntary contractions. However, this so-called force enhancement has not been studied for submaximal voluntary efforts; therefore, it is not known whether this property affects ...

This study was designed to investigate the modulations of H-reflex and V-wave responses during passive and maximal active dynamic actions. Experiments were performed on 16 healthy males [age: 24 +/- 4 (SD) yr]. Maximal H-reflexes (Hmax) and M-waves (MmaxR) were evoked at the same muscle length during passive isometric, shortening and lengthening actions and during maximal voluntary isometric, c...

The effect of isometric skeletal muscle contraction on the performance of the normal left ventricle was studied noninvasively in 20 subjects. Studies were conducted at rest and at 3 minutes of isometric hanedrip exercise at 50 per cent of maximum voluntary contraction, and consisted of simultaneous recording of left ventricular echocardiogram, external carotid pulse, phonocardiogram, and electr...

An elderly hemiplegic patient participating in an EMG biofeedback training program was observed to produce a synergistic flexion movement of the plegic (determined by functional evaluations) upper limb while yawning. In the course of the training sessions the electrical activity of the anterior deltoid (the target muscle) was recorded during yawning. These peak EMG values were greatly facilitat...

BACKGROUND the magnitude of cardiovascular responses is dependent on the static and dynamic components as well as the duration and intensity of the contraction performed. OBJECTIVE to evaluate the heart rate responses to different percentages of isometric contractions in 12 patients (63 ± 11.6 years) with coronary artery disease and/or risk factors for coronary artery disease that were partic...

The aim of this study was to perform an electromyographic and kinetic comparison of two commonly used hamstring eccentric strengthening exercises: Nordic Curl and Ball Leg Curl. After determining the maximum isometric voluntary contraction of the knee flexors, ten female athletes performed 3 repetitions of both the Nordic Curl and Ball Leg Curl, while knee angular displacement and electromyogra...

The influence of adipose tissue thickness (ATT) on near-IR spectroscopy (NIRS) measurements in vivo was studied in the human flexor digitorum superficialis muscle at rest and during sustained isometric handgrip exercise. NIRS was used for the quantitative measurement of muscle O(2) consumption (mV.O(2)) and forearm blood flow (FBF) in 78 healthy subjects. Skinfold thickness ranged from 1.4 to 8...

The roles of muscle afferent activity and central drive in controlling the compromised cardiovascular system of patients with mild chronic heart failure (CHF) during isometric exercise were examined. Blood pressure and heart rate responses were recorded in eight stable CHF patients (ejection fraction 20-40%; age 62+/-11 years) and in nine healthy age-matched controls during voluntary and electr...