Search results for "Contractility"

ADENOSINE IS A MODULATOR OF THE CONTRACTILITY OF THE DUODENAL LONGITUDINAL MUSCLE IN MICE

2009

Activation of human plantar flexor muscles increases after electromyostimulation training

2002

Neuromuscular adaptations of the plantar flexor muscles were assessed before and subsequent to short-term electromyostimulation (EMS) training. Eight subjects underwent 16 sessions of isometric EMS training over 4 wk. Surface electromyographic (EMG) activity and torque obtained under maximal voluntary and electrically evoked contractions were analyzed to distinguish neural adaptations from contractile changes. After training, plantar flexor voluntary torque significantly increased under isometric conditions at the training angle (+8.1%, P< 0.05) and at the two eccentric velocities considered (+10.8 and +13.1%, P < 0.05). Torque gains were accompanied by higher normalized soleus EMG a…

Progressive versus rapid rate of contraction during 7 wk of isometric resistance training.

2001

The aim of this study was to compare the effects of isometric training performed with progressive versus rapid rate of contraction on the knee extensor neuromuscular properties over a 7-wk period.Sixteen healthy male subjects trained quadriceps femoris muscle in a leg extension machine three times a week during 7 wk. The training sessions consisted of six sets of six maximal isometric contractions. A first group trained by performing progressive contractions lasting 4 s, whereas a second group performed contractions with a rapid rate of contraction (i.e., ballistic contractions) lasting about 1 s.Both groups significantly increased the isometric and isokinetic voluntary torque, and the resp…

Left ventricular function after acute myocardial infarction

1976

10 patients with their first AMI were studied within the first 48 hours and again after 3 weeks. Central and peripheral haemodynamics (CI, SV, SW, TPR) were examined, including indices of contractility (dp/dtmax) and wall stiffness (deltaP/deltaV, relation deltaP/deltaV to P) of the left ventricle. In the early phase CI and SW, as well as LV dp/dtmax were depressed in accordance with symptoms of LV failure. deltaP/deltaV was increased. Elevation of LVEDP correlated well with ventricular gallop rhythm, but less consistently with LV functional disturbance. During convalescence CI increased uniformly, both in digitalized and non-digitalized individuals. In contrast heart rate, aortic pressure,…

Left ventricular function analyzed by Doppler and echocardiographic methods in short-term hypothyroidism

1995

Abstract In conclusion, a significant reversible decrease in contractility and an impaired diastolic relaxation was demonstrated in patients with short-term hypothyroidism. This must be considered in patients with preexisting heart disease.

Biomechanical Determinants of Right Ventricular Failure in Pulmonary Hypertension.

2018

Pulmonary hypertension (PH) is a disease characterized by progressive adverse remodeling of the distal pulmonary arteries, resulting in elevated pulmonary vascular resistance and load pressure on the right ventricle (RV), ultimately leading to RV failure. Invasive hemodynamic testing is the gold standard for diagnosing PH and guiding patient therapy. We hypothesized that lumped-parameter and biventricular finite-element (FE) modeling may lead to noninvasive predictions of both PH-related hemodynamic and biomechanical parameters that induce PH. We created patient-specific biventricular FE models that characterize the biomechanical response of the heart and coupled them with a lumped-paramete…

Localization of Muscle Edema and Changes on Muscle Contractility After Dry Needling of Latent Trigger Points in the Gastrocnemius Muscle.

2019

Background Myofascial trigger points (TrPs) are hyperirritable spots within taut bands of skeletal muscles that elicit local and referred pain when stimulated. Among the variety of techniques used for treating TrPs, dry needling (DN) is the most commonly applied intervention. The physiological mechanisms underlying the effects of DN remain to be elucidated. Objective To examine changes in skeletal muscle after DN in the area where the TrP is located. Methods We measured in vivo changes that occur in human skeletal muscle one hour after DN over a TrP with magnetic resonance imaging (MRI) and tensiomyography. The study included 18 asymptomatic subjects with a latent TrP in one medial gastrocn…

Evidence of neuromuscular fatigue after prolonged cycling exercise

2000

International audience; Purpose: The purpose of this study was to analyze the effects of prolonged cycling exercise on metabolic, neuromuscular, and biomechanical parameters. Methods: Eight well-trained male cyclists or triathletes performed a 2-h cycling exercise at a power output corresponding to 65% of their maximal aerobic power. Maximal concentric (CON; 60, 120, 240°s 1), isometric (ISO; 0°s 1), and eccentric (ECC; 120,-60°s 1) contractions, electromyographic (EMG) activity of vastus lateralis (VL) and vastus medialis (VM) muscles were recorded before and after the exercise. Neural (M-wave) and contractile (isometric muscular twitch) parameters of quadriceps muscle were also analyzed u…

Neural Activation During Submaximal Contractions Seems More Reflective of Neuromuscular Ageing than Maximal Voluntary Activation

2016

International audience; This study aimed at testing the hypothesis that differences in neural activation strategy during submaximal but not maximal plantarflexions exist between young and older men. Eleven young men (YM, 26 +/- 4 years) and thirteen old men (OM, 76 +/- 3 years) volunteered for the investigation. Maximal voluntary torque (MVT) was 38.2%, lower (p < 0.001) in OM than in YM, while voluntary activation was equivalent (similar to 97%). The relationship between the interpolated twitch torque and the voluntary torque (IT-VT relationship) was composite (curvilinear + exponential) for both age-groups. However, the OM showed accentuated concavity, as attested by the occurrence of the…

DIFFERENT ABILITY OF TRIFLUOPERAZINE TO INHIBIT AGONIST-INDUCED CONTRACTION OF LUNG PARENCHYMA STRIPS FROM CONTROL AND SENSITIZED GUINEA-PIGS

1988

Abstract There is increasing interest in the therapeutic potential of calcium antagonists in asthma. Among them the use of calmodulin antagonists deserves consideration. In the present work the effect of trifluoperazine on contractions generated by different mechanisms (CaCl2, KCl, acetylcholine, histamine and 5-hydroxytryptamine) in lung parenchyma strip isolated from control and actively sensitized guinea-pigs has been studied. Trifluoperazine produced both in unsensitized and sensitized lung strips, a concentration-dependent, right, downward displacement of the concentration-response curves to the agonists used, although the sensitization procedure resulted in a potentiation in the abili…