Search results for "contraction"
showing 10 items of 1092 documents
Responsiveness of Electromyographically Assessed Skeletal Muscle Inactivity – methodological exploration and implications for health benefits
2022
Abstract Prolonged sedentary behaviour is detrimental to health due to low contractile activity in large lower extremity muscle groups. This muscle inactivity can be measured with electromyography (EMG), but it is unknown how methodological factors affect responsiveness longitudinally. This study aimed to rank 16 different EMG inactivity thresholds based on their responsiveness (absolute and standardized effect size, responsiveness) using data from a randomized controlled trial targeted at reducing and breaking up sedentary time (InPact, ISRCTN28668090). EMG inactivity duration and usual EMG inactivity bout duration (weighted median of bout lengths) were measured from large lower extremity …
Selective chiral inhibition of Ca2+ entry promoted by bisbenzyltetrahydroisoquinolines in rat uterus.
1992
Abstract The effects of diltiazem and six bisbenzyltetrahydroisoquinoline alkaloids (antioquine, 7-O-methylantioquine, dimethylantioquine, monterine, granjine and cordobimine) were studied in rat isolated uterus in order to clarify the mechanisms of their relaxant actions. All the compounds tested completely relaxed KCl-induced contractions and totally or partially inhibited oxytocin-induced rhythmic contractions. Only alkaloids with absolute configurations (1R,1′S or 1R,1′R) acted intracellularly, promoting relaxation of contractile responses induced by oxytocin in a Ca2+-free medium, as does papaverine. Alkaloids of the antioquine series (1S,1′R) selectively inhibited Ca2+ entry. The grea…
Effects of sulphonylureas on spontaneous motility and induced contractions in rat isolated uterus
1986
Abstract To clarify the action of sulphonylureas on calcium, the effect of tolbutamide and ghbenclamide has been investigated on a Ca-dependent process, the contractile activity of uterine smooth muscle. Both sulphonylureas antagonized the contractions evoked by CaCl2 in a non-competitive manner when the uterus was maintained in depolarizing solution and did not affect the spontaneous contractions of rat uterus. The capacity of tolbutamide and ghbenclamide to relax vanadate-induced contraction of rat uterus in Ca-free medium suggests that sulphonylureas may have an intracellular site of action related to cytosolic free Ca levels, or effect a reduction in Ca action.
Muscle function in monozygotic female twin pairs discordant for hormone replacement therapy
2011
Introduction: Postmenopausal monozygotic twin pairs discordant for hormone replacement therapy (HRT) provide an advantageous study design controlling for genetic background for elucidating the relationships between aging, sex hormone levels, muscle strength, contractile capacity, and fatigability. Methods: Thirteen postmenopausal monozygotic twin pairs discordant for HRT were measured for maximal voluntary torque (MVC) and twitch characteristics using electrical stimulation before and after intermittent dynamic plantarflexor exercise until exhaustion. Results: Peak twitch torque was 32% higher in HRT users than in their non-HRT, genetically identical sisters (P = 0.002), but MVC did not dif…
Fixed point results for α-implicit contractions with application to integral equations
2016
Recently, Aydi et al. [On fixed point results for α-implicit contractions in quasi-metric spaces and consequences, Nonlinear Anal. Model. Control, 21(1):40–56, 2016] proved some fixed point results involving α-implicit contractive conditions in quasi-b-metric spaces. In this paper we extend and improve these results and derive some new fixed point theorems for implicit contractions in ordered quasi-b-metric spaces. Moreover, some examples and an application to integral equations are given here to illustrate the usability of the obtained results.
: Quantification of the morphological evolution of the Hominid skull and heterochronies
1998
Comparisons of adult skulls of various species of great apes, fossil hominids and modem humans in the sagittal, Francfort and ortho-sagittal planes reveal a series of three separate organisation plans: 'GreatApe', 'Australopithecine'and 'Homo', tbe latter including primitive men (Homo ergaster-erectus-neandertalensis) and modern humans (Homo sapiens). Morphological changes between these plans are quantified for the first time here by vector fields. This study confirms the existence of cranio-facial contraction, which occurs as a series of leaps. The juvenile morphology of the great ape skull is broadly preserved in adult Homo sapiens, suggesting that numerous heterochronies have occurred in…
Effects of magnesium chloride on the contractile response of uterus to several agonists in Ca-free solution
1987
Abstract The effects of MgCl2 on the oestrogen-dominated rat uterus have been examined. Tissues were preincubated in a Ca2+- and Mg2+-free medium containing 3 mM EDTA. Most experiments were subsequently performed in a similar medium containing either no EDTA or EDTA (1 mM). When MgCl2 was added cumulatively (1–32 mM) no contractile responses were obtained in Ca,Mg-free medium or in Ca,Mg-free high K+ solution. When 2 mM CaCl2 as added, a sustained contraction was obtained. Subsequent addition of cumulative concentrations of MgCl2 caused concentration-dependent relaxation. Oxytocin, 2 μM, produced a small and sustained contraction in a Ca,Mg-free medium. Addition of MgCl2, 2 mM, increased th…
7 YEARS OF EUROPEAN FUNDING IN ROMANIA - BETWEEN SUCCESS AND FAILURE
2015
This paper aims to achieve an overall picture of the absorption rate of European funds in Romania for the 2007-2013 programming period and to propose a series of recommendations on the steps our country needs to follow in order to improve the process of accessing and implementation of structural instruments at national level. These recommendations focus on preventing obtaining a low rate of absorption of EU funds allocated to Romania in the multiannual financial framework 2014-2020 , thus preventing wastage prospects of economic and social modernization , that these funds offer.
Might as well jump: Sound affects muscle activation in skateboarding
2014
The aim of the study is to reveal the role of sound in action anticipation and performance, and to test whether the level of precision in action planning and execution is related to the level of sensorimotor skills and experience that listeners possess about a specific action. Individuals ranging from 18 to 75 years of age - some of them without any skills in skateboarding and others experts in this sport - were compared in their ability to anticipate and simulate a skateboarding jump by listening to the sound it produces. Only skaters were able to modulate the forces underfoot and to apply muscle synergies that closely resembled the ones that a skater would use if actually jumping on a ska…
Evoked responses to transcranial and electrical stimulation during isometric and lengthening contractions of the soleus muscle
2011
The aim of this study was to assess differences in motor control between isometric and lengthening contractions of the soleus muscle. Evoked responses to TMS (MEPs) and electrical stimulation of the peripheral nerve (H-reflexes) where recorded at rest and during isometric and lengthening contractions of the soleus muscle at 20%, 40%, 60% and 80% MVC. Torque and background EMG were averaged over a time window of 100ms prior to stimulation. MEPs were found to be significantly lower (P < 0.05) during lengthening contractions compared to isometric contractions at 40%, 60% and 80% MVC (10.95 ± 0.05 mV vs 9.93 ±0.06 mV ; 1.47 ± 0.07 mV vs 9.7 ± 0.08 mV; 11.48 ± 0.08 mV ± vs 10.14 ± 0.07 mV). The …