Search results for "Contraction"
showing 10 items of 1092 documents
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…
Allometrically scaled explosive strength, but not static strength or maximal oxygen uptake is associated with better central processing time in young…
2020
BACKGROUND: We aimed to examine the associations of cardiorespiratory fitness (CRF), static strength and explosive strength with cognitive functions in young males. METHODS: Eighty-six young males (age 16-24 years) participated in the study and took part in a number of tests including: static strength (grip strength test), explosive strength (Sargent jump test), and CRF (via direct measure of maximal oxygen uptake (VO2max)). Static strength and explosive strength were scaled by allometrically modeled skeletal muscle mass (SMM) and height while VO2max was scaled by SMM and body mass (BM). Cognition was assessed by inhibitory control, simple and choice reaction time tasks using computerized C…
Muscle Activity During Unilateral vs. Bilateral Battle Rope Exercises.
2015
High training intensity is important for efficient strength gains. Although battle rope training is metabolically demanding, no studies have quantified intensity of muscle activity during this type of training. This study analyzes muscle activity during unilateral alternating waves vs. bilateral waves of battle rope training. Twenty-one volunteers participated in a repeated-measures study on 2 different occasions. Surface electromyographic signals were recorded from the anterior deltoid (AD), external oblique (OBLIQ), lumbar erector spinae (LUMB), and gluteus medius (GM) during bilateral waves and unilateral waves and were normalized to the maximum voluntary isometric contraction (MVIC). Re…
Strength, [corrected] endurance or combined training elicit diverse skeletal muscle myosin heavy chain isoform proportion but unaltered androgen rece…
2009
We investigated whether the myosin heavy chain (MyHC) proportion and androgen receptor (AR) concentration in skeletal muscle differ following 21 weeks of strength, endurance and combined training in untrained older men. Strength (S) and endurance (E) groups trained twice per week and combined (S+E) group trained four times per week (two strength and two endurance). Muscle biopsies were obtained before and after the training period from m. vastus lateralis (VL) and AR mRNA and protein concentration and MyHC proportion were determined. 1RM increased during the training period in S, S+E and E but the changes were greater in S and S+E than in E. Statistically significant increases were observed…
High-speed rotational angioplasty-induced echo contrast in vivo and in vitro optical analysis
1992
High-speed rotational angioplasty is being evaluated as an alternative interventional device for the endovascular treatment of chronic coronary occlusions. It has been postulated that this type of angioplasty device may produce particulate debris or cavitations that induce myocardial ischemia. To determine the clinical presence of myocardial ischemia during rotational angioplasty, echocardiographic monitoring for wall motion abnormalities was performed in 9 patients undergoing rotational atheroablation using the Auth Rotablator for 10-sec intervals at 150,000 and 170,000 rpm. No wall motion abnormalities were detected in 5 patients evaluated with transesophageal echocardiography or in 4 pat…
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…
Neuromuscular Adaptations to Low-Frequency Stimulation Training in a Patient with Chronic Heart Failure
2008
Electrical myostimulation (EMS) has recently been proposed as an interesting rehabilitation tool in patients with chronic heart failure (CHF). Although its beneficial effects on exercise capacity and muscle strength have been demonstrated, the neuromuscular adaptations responsible for improved performance are not well understood. This preliminary case report was therefore planned to investigate the neural and muscular adaptations to a 5-wk EMS program in one patient. An increase in maximal strength (10.5%) was accompanied by increased twitch torque (13.9%) and slowing of muscle contractile properties (half-relaxation time, time to peak torque, and maximal rate of relaxation increased by 7.1…
Combined medical and mechanical recanalization in acute myocardial infarction
1985
A technique of combined medical and mechanical recanalization was employed in 96 patients with acute transmural myocardial infarction. The mean time between onset of symptoms and admission to hospital was 170 +/- 65 min (X +/- SD). After 10 +/- 16 min, 250,000 U streptokinase was administered intravenously for 20 min. Intracoronary thrombolysis was commenced within 38 +/- 14 min. First coronary angiograms demonstrated reperfusion, an open vessel in 25/96 patients (26%). In 15/71 patients (21%) reperfusion occurred during thrombolysis therapy, before mechanical recanalization could be performed. Recanalization was achieved mechanically in 37/71 patients (52%) with occluded coronary vessels. …