Background: Based on previously reported changes in muscle metabolism that could increase susceptibility to fatigue, we speculated that patients with chronic obstructive pulmonary disease (COPD) have reduced quadriceps endurance and that this will be correlated with the proportion of type I muscle fibres and with the activity of oxidative enzymes. Methods: The endurance of the quadriceps was ev...

PETERSON, JOHN W., AND RICHARD J. PAUL. Effects of initial length and active shortening on vascular smooth muscle contractility. Am. J. Physiol. 227(5) : 1019-1024. 1974.-The active isometric tension-length relation has been studied in bovine mesenteric vein at 37°C under a variety of experimental conditions, including both passive and active changes in muscle length. The rest length Lo , defin...

The purpose was to investigate the contribution of mechanical damage to sarcomeres to the greater susceptibility of dystrophic muscle fibers to contraction-induced injury. Single stretches provide an effective method for studying mechanical factors that contribute to the initiation of contraction-induced injury. We hypothesized that, after single stretches, the deficits in isometric force would...

The suppression of spontaneous Ca2+ spikes and isometric contractions by gingerols and their chemically related compounds was examined using the single sucrose gap method. Most of the congeners tested suppressed spontaneous contraction, which was not necessarily accompanied by the suppression of Ca2+ spikes. The most potent analogues for Ca2+ spike suppression were (+/-)-[6]-gingerol (0.3 mM) a...

Studies of cardiac muscle energetics have traditionally used contraction protocols with strain patterns that bear little resemblance to those observed in vivo. This study aimed to develop a realistic strain protocol, based on published in situ measurements of contracting papillary muscles, for use with isolated preparations. The protocol included the three phases observed in intact papillary mu...

Force depression after active shortening has been observed in different muscle preparations. It has been assumed that force depression is caused by the development of sarcomere length nonuniformities after shortening. However, this hypothesis has never been investigated in a preparation where individual sarcomere lengths could be directly measured. Here, we investigated force depression in sing...

When a skeletal muscle is actively stretched, its force is substantially greater than the force obtained for a muscle contracting purely isometrically [1]. This phenomenon has been observed for more than fifty years, is an accpeted property of skeletal muscle contraction, and has been termed force enhancement [2]. When performing experiments on force enhancement in human skeletal muscles, we ob...

The present study determines the effects of summation of contraction on joint kinematics in human ankle and mechanomyography (MMG) signals during non-isometric contraction. The excursion and angular velocity of dorsiflexion and eversion were measured during several summation profiles during non-isometric contractions. The joint kinematics parameters and MMG responses to 1-8 pulses at a constant...

We tested the hypotheses that lengthening contractions, isometric contractions, and passive stretches increase muscle inflammatory cells (neutrophils and macrophages) and that prior conditioning with lengthening contractions, isometric contractions, or passive stretches reduces neutrophils and macrophages after subsequent lengthening contractions. Extensor digitorum longus muscles in anesthetiz...

This study aimed to examine the correlation of different dry land strength and power tests with swimming start performance. Twenty international level female swimmers (age 15.3 ± 1.6 years, FINA point score 709.6 ± 71.1) performed the track freestyle start. Additionally, dry land tests were conducted: a) squat (SJ) and countermovement jumps (CMJ), b) squat jumps with additional resistance equiv...