There exists no examination of what is the minimum anti-hypertensive threshold intensity for isometric exercise training. Twenty two normotensive participants were randomly assigned to training intensities at either 5 % or 10 % of their maximal contraction. Twenty participants completed the study. Clinical meaningful, but not statistically significant, reductions in systolic blood pressure were observed in both 5 % and 10 % groups -4.04 mm Hg (95 % CI -8.67 to +0.59, p=0.08) and -5.62 mm Hg (95 % CI -11.5 to +0.29, p=0.06) respectively after 6 weeks training. No diastolic blood pressure reductions were observed in either 5 % -0.97 mm Hg (95 % CI -2.56 to +0.62, p=0.20) or 10 % MVC +1.8 mm Hg (95 % CI -1.29 to +4.89, p=0.22) groups respectively after training. In those unable to complete isometric exercise at the traditional 30 % intensity, our results suggest there is no difference between 5 and 10 % groups and based on the principle of regression to the mean, this could mean both interventions induce a similar placebo-effect.

• MeSH
• dospělí MeSH
• hypertenze terapie   MeSH
• isometrická kontrakce * MeSH
• krevní tlak * MeSH
• lidé středního věku MeSH
• lidé MeSH
• síla ruky fyziologie   MeSH
• srdeční frekvence MeSH
• terapie cvičením * MeSH
• zdraví dobrovolníci pro lékařské studie MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• randomizované kontrolované studie MeSH
• srovnávací studie MeSH

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 of rhythmic exercise. There was similarity between steady state brachial blood flow velocity (BBV) extrapolated from single handgrip contractions and during 2 min of rhythmic exercise for 20 % (10.0+/-3.8 cm/s vs. 10.2+/-2.6 cm/s, r=0.93, p=0.003) and 40 % of maximum contractions (14.2+/-5.5 cm/s vs. 15.6+/-3.4 cm/s, r=0.88, p=0.009), but not for 10 % (7.5+/-4.1 cm/s vs. 5.7+/-3.3 cm/s, r=0.94, p=0.018). BBV progressively rose substantially higher during rhythmic contractions than peak BBV observed during single contractions at matched intensity. Respective peak BBV during single contractions and steady state BBV rhythmic contractions were 4.4+/-2.1 and 5.7+/-3.3 cm.s(-1) at 10 % forearm strength (p=0.14), 5.6+/-2.4 and 10.2+/-2.8 cm.s(-1) at 20 % (p=0.002), and 7.0+/-2.5 and 15.6+/-3.6 cm.s(-1) at 40 % (p=0.003). In conclusion, there is similarity between the summated blood flow velocity calculated from a single 1 s muscle contraction and the steady state blood flow velocity response of rhythmic exercise.

• MeSH
• cvičení fyziologie   MeSH
• hyperemie etiologie   MeSH
• ischemie etiologie   MeSH
• isometrická kontrakce * MeSH
• lidé MeSH
• mladý dospělý MeSH
• regionální krevní průtok * MeSH
• ruka krevní zásobení   MeSH
• rychlost toku krve MeSH
• zdraví dobrovolníci pro lékařské studie MeSH
• Check Tag
• lidé MeSH
• mladý dospělý MeSH
• mužské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH

The hormone leptin, which is thought to be primarily produced by adipose tissue, is a polypeptide that was initially characterized by its ability to regulate food intake and energy metabolism. Leptin appears to signal the status of body energy stores to the brain, resulting in the regulation of food intake and whole-body energy expenditure. Subsequently, it was recognized as a cytokine with a wide range of peripheral actions and is involved in the regulation of a number of physiological systems including reproduction. In the fed state, leptin circulates in the plasma in proportion to body adiposity in all species studied to date. However other factors such as sex, age, body mass index (BMI), sex steroids and pregnancy may also affect leptin levels in plasma. In pregnant mice and humans, the placenta is also a major site of leptin expression. Leptin circulates in biological fluids both as free protein and in a form that is bound to the soluble isoform of its receptor or other binding proteins such as one of the immunoglobulin superfamily members Siglec-6 (OB-BP1). Although the actions of leptin in the control of reproductive function are thought to be exerted mainly via the hypothalamic-pituitary-gonadal axis, there have also been reports of local direct effects of leptin at the peripheral level, however, these data appear contradictory. Therefore, there is a need to summarize the current status of research outcomes and analyze the possible reasons for differing results and thus provide researchers with new insight in designing experiments to investigate leptin effect on reproduction. Most importantly, our recent experimental data suggesting that reproductive performance is improved by decreasing concentrations of peripheral leptin was unexpected and cannot be explained by hypotheses drawn from the experiments of excessive exogenous leptin administration to normal animals or ob/ob mice.

• MeSH
• fertilita MeSH
• implantace embrya * MeSH
• leptin metabolismus   MeSH
• lidé MeSH
• rozmnožování * MeSH
• signální transdukce * MeSH
• těhotenství MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• těhotenství MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH