Search results for "contract"
showing 10 items of 1719 documents
The Rolf Method of Structural Integration and Pelvic Floor Muscle Facilitation: Preliminary Results of a Randomized, Interventional Study
2020
The management of pelvic floor dysfunctions might need to be based on a comprehensive neuro-musculoskeletal therapy such as The Rolf Method of Structural Integration (SI). The aim of the study was to evaluate the pelvic floor muscle (PFM) after the tenth session of SI by using surface electromyography (sEMG). This was a randomized, interventional study. Thirty-three healthy women were randomly assigned to the experimental (SI) or control group. The outcome measures included PFM bioelectrical activity, assessed using sEMG and endovaginal probes. An intervention in the SI group included 60 min of SI once a week, and teaching on how to contract and relax PFMs
Modulatory action of acetylcholine on cerebrovascular sympathetic neurotransmission
1991
1. Acetylcholine (10 micrograms/min) diminished the electrically-induced cerebral blood flow reductions. Atropine (1-2 mg) partially blocked this inhibitory effect. 2. Exogenously administered noradrenaline (1-10 micrograms) and tyramine (50-500 micrograms) reduced cerebral blood flow but this effect was unchanged by acetylcholine infusion. 3. Acetylcholine inhibited the nonadrenergic component of the electrically-induced contraction at a concentration greater than or equal to 10(-6) M and potentiated the adrenergic component at a concentration greater than or equal to 10(5) M. Atropine 10(-7) M) inhibited both of these effects. In addition, acetylcholine (10(-4) M) enhanced the electricall…
Umbilical artery blood flow velocity waveforms during variable decelerations of the fetal heart rate
1991
Blood flow velocities of the umbilical arteries were measured by Doppler ultrasonography during variable decelerations of the fetal heart rate. The flow velocity waveforms, being normal between uterine contractions, showed either an unchanged flow velocity waveform with an exclusive fetal heart rate effect on end-diastolic velocities or a rapid change to absent and reverse diastolic flow during the decelerations, indicating an abrupt increase in placental resistance with a halt in placental perfusion. Computer-aided reconstruction of the fetal heart rate curve revealed the exact temporal relationship between the reduction of umbilical artery perfusion and deceleration of fetal heart rate. W…
Tensiomyographical responsiveness to peripheral fatigue in quadriceps femoris
2020
Background Fatigue influences athletic performance and can also increase the risk of injury in sports, and most of the methods to evaluate it require an additional voluntary effort. Tensiomyography (TMG), which uses electrical stimulation and a displacement sensor to evaluate muscle contraction properties of one or more muscle bellies, has emerged as a technique that can assess the presence of peripheral and central fatigue without requiring additional voluntary efforts. However, the evaluation of the TMG’s ability to detect fatigue is limited, both at the level of muscle bellies and statistical methods. Thus, the aim of the present study was twofold: (i) to examine and compare the tensiom…
Effects of combined electromyostimulation and gymnastics training in prepubertal girls.
2011
This study investigated the effects of a 6-week combined electromyostimulation (EMS) and gymnastic training program on muscle strength and vertical jump performance of prepubertal gymnasts. Sixteen young women gymnasts (age 12.4 ± 1.2 yrs) participated in this study, with 8 in the EMS group and the remaining 8 as controls. EMS was conducted on knee extensor muscles for 20 minutes 3 times a week during the first 3 weeks and once a week during the last 3 weeks. Gymnasts from both groups underwent similar gymnastics training 5-6 times a week. Isokinetic torque of the knee extensors was determined at different eccentric and concentric angular velocities ranging from -60 to +240° per second. Jum…
Alterations of Neuromuscular Function After Prolonged Running, Cycling and Skiing Exercises
2004
It is well known that impairment of performance resulting from muscle fatigue differs according to the types of contraction involved, the muscular groups tested and the exercise duration/intensity. Depending on these variables, strength loss with fatigue can originate from several sites from the motor cortex through to contractile elements. This has been termed 'task dependency of muscle fatigue'. Only recently have studies focused on the origin of muscle fatigue after prolonged exercise lasting 30 minutes to several hours. Central fatigue has been shown to contribute to muscle fatigue during long-distance running by using different methods such as the twitch interpolation technique, the ra…
Interstitial washout and hydrolysis of acetylcholine in the perfused heart
1982
The efflux of acetylcholine, of radioactively labelled acetylcholine and choline, into the venous effluent of the perfused chicken heart was studied to determine the kinetics of both interstitial washout and hydrolysis of acetylcholine. Stimulation of both cervical vagus nerves (e.g., for 5 s at 40 Hz) caused a release of acetylcholine, which appeared partially unhydrolyzed in the venous effluent, and reduced force of contraction and heart rate. For comparison, labelled acetylcholine or choline was infused for 5 s into the heart and again the venous efflux of either substance was determined. It was found that the kinetics of efflux of acetylcholine or choline from the interstitial space wer…
Selective muscle hypertrophy, changes in EMG and force, and serum hormones during strength training in older women.
2001
Effects of strength training (ST) for 21 wk were examined in 10 older women (64 ± 3 yr). Electromyogram, maximal isometric force, one-repetition maximum strength, and rate of force development of the leg extensors, muscle cross-sectional area (CSA) of the quadriceps femoris (QF) and of vastus lateralis (VL), medialis (VM), intermedius (VI) and rectus femoris (RF) throughout the lengths of 3/12–12/15 (Lf) of the femur, muscle fiber proportion and areas of types I, IIa, and IIb of the VL were evaluated. Serum hormone concentrations of testosterone, growth hormone (GH), cortisol, and IGF-I were analyzed for the resting, preexercise, and postexercise conditions. After the 21-wk ST, maximal for…
Characterization of choline efflux from the perfused heart at rest and after muscarine receptor activation.
1986
The resting efflux of choline from perfused chicken hearts varied from 0.4 to 2.6 nmol/g min, but was constant for at least 80 min in the individual experiments. The rate of choline efflux was found to be equal to the rate of choline formation in the heart, which, from the following reasons, was essentially due to hydrolysis of choline phospholipids. Cardiac content of choline phospholipids (7,200 nmol/g) was much higher than that of acetylcholine (5.5 nmol/g). Resting release of acetylcholine was 0.016 nmol/g min and, after inhibition of cholinesterase, only about 0.1 nmol/g min. Resting efflux of choline was reduced by mepacrine, a phospholipase A2 inhibitor, by perfusion with a Ca2+-free…
Oxygen and substrate deprivation on isolated rat cardiac myocytes : temporal relationship between electromechanical and biochemical consequences
1990
The effects of hypoxia and reoxygenation on action potentials (AP), contractions, and certain biochemical parameters were studied in isolated rat ventricular myocytes in monolayer culture in the presence and absence of glucose. Substrate deprivation alone had no influence on the basal properties. In the presence of glucose, a 4-h hypoxic treatment caused only a moderate decrease in AP amplitude and rate. In substrate-free conditions, hypoxia induced a gradual decline in plateau potential level and in AP duration and rate, followed by rhythm abnormalities and a failure of the electromechanical coupling. Spontaneous AP generation then ceased, and the resting potential decreased with increase…