Search results for "Contraction"
showing 10 items of 1092 documents
Training the Vertical Jump to Head the Ball in Soccer
2012
R esearchers involved in the training methodology to improve jump ability proposed a variety of techniques and exercise modalities (22,15,4). Nevertheless, the question on what percentage of training should be dedicated to strength and what to power seems unresolved. First of all, to better understand the matter, we have to stress the difference between strength and power. Generally speaking, in athletics, the rate of force development (RFD) is much more important than strength alone; the average RFD (mRFD) can be estimated as the ratio Fmax/Tmax, where Tmax is the time to reach the peak force, whereas Fmax is the maximum force. This ratio is also named explosive strength, commonly computed…
Vitamin and Mineral Supplementation and Neuromuscular Recovery after a Running Race
2006
International audience; Purpose: This double-blind study investigated the effects of vitamin and mineral complex supplementation on the neuromuscular function of the knee-extensor muscles after a prolonged trail running race. Methods: Twenty-two well-trained endurance runners took either placebo (Pl group) or vitamins and minerals (Vm group) for 21 d before the race and for 2 d after the race. Maximal voluntary contractions (MVC) and surface EMG activity of the vastus lateralis (VL) muscle were recorded before (pre) and 1 h (post), 24 h (post 24) and 48 h (post 48) after the race. Central activation ratio (CAR), neural (M-wave), and contractile (muscular twitch) properties of the quadriceps…
Effects of a vitamin D3 analogue in a rat model of bladder outlet obstruction
2006
OBJECTIVES To explore the effect of the vitamin D3 analogue, BXL-628, on some of the consequences of bladder outlet obstruction (BOO), e.g. hypertrophy and loss of contractile function, as vitamin D3 and BXL-628 inhibit prostate and bladder cell growth in vitro, and there are receptors for vitamin D in rat and human bladder. MATERIAL AND METHODS In female rats, BOO was produced by a standardized method; one group received daily BXL-628 (150 µg/kg per day) and the remaining rats received vehicle. Sham-operated rats received BXL-628 or vehicle. After 2 weeks, the conscious rats were assessed by cystometry. Plasma calcium levels were determined and in vitro contractility assessed at the end of…
Effets d'une complémentation nutritionnelle en vitamines et minéraux sur la chute de force et les marqueurs biologiques consécutifs à un exercice exc…
2007
Purpose. – The effects of vitamins and minerals complex supplementation on maximal voluntary contraction decrease (FMV) and biological markers following an eccentric exercise at old people. Method. – Sixteen elderly subjects took either placebo (Pl group) or vitamins and minerals (Isoxan Senior, NHS, Rungis, France) (group S) for 21 d before an eccentric exercise and for 3 d after the exercise. The FMV and surface EMG activity (RMS) of the vastus lateralis (VL), vastus medialis (VM) and rectus femoris (RF) were recorded before (Pre), immediately after (Post), 24 h (Post 24) and 48 h (Post 48) after the exercise. CCVThe creatine kinase (CK), lactate deshydrogenase, malondialdehyde, and tumor…
Two-Perfect Fluid Interpretation of an Energy Tensor
1990
The paper contains the necessary and sufficient conditions for a given energy tensor to be interpreted as a sum of two perfect fluids. Given a tensor of this class, the decomposition in two perfect fluids (which is determined up to a couple of real functions) is obtained.
User-oriented evaluation of mechanical single-channel axial pipettes.
2013
Hand tools should be designed so that they are comfortable to use, fit the hand and are user-oriented. Six different manual, single-channel axial pipettes were evaluated for such objective outcomes as muscular activity, wrist postures and efficiency, as well as for subjective outcomes concerning self-assessed features of pipette usability and musculoskeletal strain. Ten experienced laboratory employees volunteered for the study. The results showed that light and short pipettes with better tool comfort resulted in reduced muscular activity and perceived musculoskeletal strain when they were compared with a long and heavy pipette. There were no differences in the efficiency between the differ…
Creatine kinase is the main target of reactive oxygen species in cardiac myofibrils.
1996
Abstract Reactive oxygen species (ROS) have been reported to alter cardiac myofibrillar function as well as myofibrillar enzymes such as myosin ATPase and creatine kinase (CK). To understand their precise mode and site of action in myofibrils, the effects of the xanthine/xanthine oxidase (X/XO) system or of hydrogen peroxide (H 2 O 2 ) have been studied in the presence and in the absence of phosphocreatine (PCr) in Triton X-100–treated cardiac fibers. We found that xanthine oxidase (XO), with or without xanthine, induced a decrease in maximal Ca 2+ -activated tension. We attributed this effect to the high contaminating proteolytic activity in commercial XO preparations, since it could be p…
Adaptations neuromusculaires des muscles extenseurs du genou : contractions fatigantes uni- vs bi-latérales
2010
The aim of this work was to determine i) the influence of the level of absolute force on the duration of the endurance time, and subsequent neuromuscular alterations in same individual at the end of an exercise performed at the same relative intensity, with one or two legs, ii) the influence of central drive on the force capacity production of the knee extensor muscles during unilateral (UL) vs. bilateral (BL) contractions, iii) activation mechanisms evolution for a serie of submaximal evoked contractions by electrostimulation (EMS). The results of the first study confirm that the endurance limit depends on the level of absolute force for the same individual, contraction duration for UL is …
Terminal tendon cell differentiation requires the glide/gcm complex.
2004
International audience; Locomotion relies on stable attachment of muscle fibres to their target sites, a process that allows for muscle contraction to generate movement. Here, we show that glide/gcm and glide2/gcm2, the fly glial cell determinants, are expressed in a subpopulation of embryonic tendon cells and required for their terminal differentiation. By using loss-of-function approaches, we show that in the absence of both genes, muscle attachment to tendon cells is altered, even though the molecular cascade induced by stripe, the tendon cell determinant, is normal. Moreover, we show that glide/gcm activates a new tendon cell gene independently of stripe. Finally, we show that segment p…
Pentamidine rescues contractility and rhythmicity in a Drosophila model of myotonic dystrophy heart dysfunction
2015
Up to 80% of individuals with myotonic dystrophy type 1 (DM1) will develop cardiac abnormalities at some point during the progression of their disease, the most common of which is heart blockage of varying degrees. Such blockage is characterized by conduction defects and supraventricular and ventricular tachycardia, and carries a high risk of sudden cardiac death. Despite its importance, very few animal model studies have focused on the heart dysfunction in DM1. Here, we describe the characterization of the heart phenotype in a Drosophila model expressing pure expanded CUG repeats under the control of the cardiomyocyte-specific driver GMH5-Gal4. Morphologically, expression of 250 CUG repeat…