background: the purpose of this study was to investigate the ratio of electromyography (em g) activities of the vastus medialis obliqus (vmo) and vastus lateralis (vl) within seven angles of knee joint range of motion using isometric contraction in open kinetic chain (ok c) and closed kinetic chain (ckc). methods: the dominant knees of 44 healthy female subjects (mean age: 24.84 with range: 20-...

introduction: according to the importance of the back extensor muscle strength in postmenopausal women, this study aimed to determine the relationship between strength and changes in the thickness of back extensor muscles during isometric contraction in healthy and osteoporotic postmenopausal women. material and methods: 42 volunteer postmenopausal women according to their bone mineral density ...

Shear stress and tyrosine phosphatase inhibitors have been shown to activate the endothelial NO synthase (eNOS) in a Ca2+/calmodulin-independent manner. We report here that isometric contraction of rabbit aorta activates eNOS by a pharmacologically identical pathway. Endothelium-intact aortic rings were precontracted under isometric conditions up to 60% of the maximal phenylephrine-induced tone...

The aim of this work was to predict blood flow responses to rhythmic handgrip exercise from one second isometric contractions. Seven healthy men were studied. Each subject performed a single 1 s handgrip contraction at 10 %, 20 % and 40 % of the maximum handgrip strength. We then repeatedly summed hyperaemic responses from single contractions to predict hyperaemic response to a prolonged bout o...

Using transcranial magnetic stimulation (TMS), differences in the excitability changes of motor evoked potentials (MEPs) between isometric (force task) and isotonic (movement task) muscle contractions in a distal (first dorsal interosseous; FDI) and a proximal (middle deltoid; MD) muscle were studied. In the FDI muscle, the active threshold of MEP recruitment was significantly lower in the isot...

• The strength of myocardial contraction is influenced directly and strongly by the intervals separating individual beats. The large number of studies on this phenomenon during the 95 years since its original recognition have recently been reviewed. Interval-dependent changes in the strength and time course of contraction result both from alterations in the duration of the active state and from...

This study assessed changes in electrical impedance myography (EIM) at different levels of isometric muscle contraction as well as during exhaustive exercise at 60% maximum voluntary contraction (MVC) until task failure. The EIM was performed on the biceps brachii muscle of 19 healthy subjects. The results showed that there was a significant difference between the muscle resistance (R) measured...

The grip strength in which subjects sustained a maximal isometric contraction for 6 seconds (the 6-second test) was compared with that for 10 seconds (the 10-second test) to clarify a reliable sustained grip strength test procedure. Fifty healthy students (22+/-4 years, 25 men and 25 women) participated in this study. Strength was measured continuously by the Dexter (Cedaron Medical Inc.). The ...

The purpose of this study was to examine differences in pressor response and cardiovagal modulation during isometric handgrip exercise (IHG) between children and adults. Beat-to-beat heart rate (HR) and blood pressure were measured in 23 prepubertal children and 23 adults at baseline and during IHG. Cardiovagal modulation was quantified by analysis of HR variability. Mean arterial pressure resp...