Search results for "Muscle Contraction"
showing 10 items of 569 documents
Mechanism of the cardiovascular activity of laudanosine: comparison with papaverine and other benzylisoquinolines.
1994
1. The activity of (+/-)-laudanosine, a benzyltetrahydroisoquinoline alkaloid, was investigated in pithed rats and rat isolated aorta. Its effects on [3H]-(+)-cis-diltiazem and [3H]-nitrendipine binding to rat cerebral cortical membranes, and on the different molecular forms of cyclic nucleotide phosphodiesterases (PDE) isolated from bovine aorta were investigated. 2. The dose-response curve to methoxamine (3-300 micrograms kg-1, i.v.) in normotensive pithed rats was shifted to the right by (+/-)-laudanosine, 3 and 6 mg kg-1. 3. (+/-)-Laudanosine inhibited in a concentration-dependent manner the contractile responses evoked by noradrenaline (NA 1 microM), depolarizing solution (KCl 80 mM) o…
Maximal voluntary isokinetic knee flexion torque is associated with femoral shaft bone strength indices in knee replacement patients.
2012
It is currently unknown whether knee replacement-associated bone loss is modified by rehabilitation programs. Thus, a sample of 45 (18 men and 25 women) persons with unilateral knee replacement were recruited; age 66 years (sd 6), height 169 cm (sd 8), body mass 83 kg (sd 15), time since operation 10 months (sd 4) to explore the associations between maximal torque/power in knee extension/flexion and femoral mid-shaft bone traits (Cortical cross-sectional area (CoA, mm(2)), cortical volumetric bone mineral density (CoD, mg/mm(3)) and bone bending strength index (SSI, mm(3))). Bone traits were calculated from a single computed tomography slice from the femoral mid-shaft. Pain in the operated …
Muscle strength and muscle endurance of middle-aged women and men associated to type, duration and intensity of muscular load at work
1988
Muscle strength and muscle endurance in groups with different occupational muscular load was studied among 60 women and 69 men. The mean age of the subjects was 52.0 +/- 3.4 years. Isometric grip and trunk strength were measured on dynamometers, and dynamic muscle endurance by sit-ups. A job analysis was done with the AET method including the assessment of intensity, duration and type of muscular work of each subject. According to the job analysis, the subjects were classified into groups with low or high muscular load at work. The maximal isometric hand grip strength of women with a load classified as long duration of static or dynamic load on the hands at work was 86 and 88%, respectively…
Corticospinal Modulations during Motor Imagery of Concentric, Eccentric, and Isometric Actions
2019
PURPOSE It is not known yet whether the neurophysiological specificity of eccentric, concentric, and isometric contractions can also be observed when these are mentally simulated. Therefore, our aim was to assess corticospinal excitability during motor imagery (MI) of different contraction types and to test whether a passive movement during MI could have additional effects. METHODS Twelve young participants imagined contractions of the wrist flexors, firstly with the arm motionless (static mode) and second, with a congruent passive movement (wrist extension during eccentric MI and wrist flexion during concentric MI). Motor-evoked potentials (MEP) and H-reflexes were elicited in flexor carpi…
Contractile hyporesponsiveness to norepinephrine of forearm veins in chronic renal failure.
2006
Background We recently reported that endothelium-dependent relaxation is impaired in forearm veins from patients with chronic renal failure. However, assessment of responses to norepinephrine remains controversial. We examined the contractile response to norepinephrine in forearm veins from patients on chronic hemodialysis and the role of nitric oxide (NO), prostanoids, and Ca 2+ -activated K + channels in this response. Methods Isometric contraction curves were obtained in rings of forearm vein from 21 dialyzed patients and 12 multiorgan donors in response to norepinephrine (1 nmol/L to 10 μmol/L) or KCl (5 to 100 mmol/L). Results Veins from uremic patients were markedly less responsive to…
Sphincter-like motion following machanical dilation of the internal inguinal ring during indirect inguinal hernia procedure
2008
INTRODUCTION: Even today, there is still great speculation as to the underlying pathogenesis of inguinal hernia. As a result, it could be extrapolated that the vast majority of repairs are based upon conjecture. Most current repairs are founded upon the principle of "closing the defect" in the anatomy, either by suturing closed under tension, covering with a mesh or obliterating the defect with a plug. Many variants of each method are refined to achieve better clinical outcomes. Yet few, if any, strive to understand a fundamental question: "What has gone wrong with the normal physiological and anatomical mechanisms that prevent abdominal structures protruding through the abdominal wall?" We…
Changes in cortico-spinal excitability following uphill versus downhill treadmill exercise
2017
International audience; An acute bout of aerobic exercise induces neuroplasticity in the motor cortex. Moreover, paired associative stimulation (PAS) is known to induce neuroplasticity in M1. However, the possible influence of the type of exercise on the neuroplastic changes remains unknown. The present study investigated the effects of two different modes of muscle contraction produced during locomotor exercise on changes in corticospinal (CS) excitability. Subjects performed two 30-min treadmill exercises at an intensity corresponding to 60% of their maximal heart rate with either a +10% (uphill) or -10% (downhill) slope. These exercises were followed or not by paired associative stimulat…
Whey proteins are more efficient than casein in the recovery of muscle functional properties following a casting induced muscle atrophy.
2013
International audience; The purpose of this study was to investigate the effect of whey supplementation, as compared to the standard casein diet, on the recovery of muscle functional properties after a casting-induced immobilization period. After an initial (I0) evaluation of the contractile properties of the plantarflexors (isometric torque-frequency relationship, concentric power-velocity relationship and a fatigability test), the ankle of 20 male adult rats was immobilized by casting for 8 days. During this period, rats were fed a standard diet with 13% of casein (CAS). After cast removal, rats received either the same diet or a diet with 13% of whey proteins (WHEY). A control group (n =…
Recovery of Damaged Skeletal Muscle in mdx Mice through Low-intensity Endurance Exercise
2013
The lack of dystrophin in mdx mice leads to cycles of muscle degeneration and regeneration processes. Various strategies have been proposed in order to reduce the muscle-wasting component of muscular dystrophy, including implementation of an exercise programme. The aim of this study was to examine how low-intensity endurance exercise affects the degeneration-regeneration process in dystrophic muscle of male mdx mice. Mice were subjected to low-intensity endurance exercise by running on a motorized Rota-Rod for 5 days/week for 6 weeks. Histomorphological analysis showed a signifi cant reduction of measured inflammatory-necrotic areas in both gastrocnemius and quadriceps muscle of exercised m…
Muscle Activity Adaptations to Spinal Tissue Creep in the Presence of Muscle Fatigue.
2016
Aim The aim of this study was to identify adaptations in muscle activity distribution to spinal tissue creep in presence of muscle fatigue. Methods Twenty-three healthy participants performed a fatigue task before and after 30 minutes of passive spinal tissue deformation in flexion. Right and left erector spinae activity was recorded using large-arrays surface electromyography (EMG). To characterize muscle activity distribution, dispersion was used. During the fatigue task, EMG amplitude root mean square (RMS), median frequency and dispersion in x- and y-axis were compared before and after spinal creep. Results Important fatigue-related changes in EMG median frequency were observed during m…