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

We investigated the convergent validity and intrasession reliability of force, velocity, and power (FVP) variables and the dynamic strength index (DSI) obtained from isometric midthigh pull (IMTP) and squat jump (SJ) testing. Fifteen male combat sports athletes (27 ± 5 years, 77 ± 9 kg, 1.76 ± 0.1 m, 14 ± 6% body fat) participated in a 2-days study. The first day involved testing familiarization, while the second was dedicated to IMTP and SJ testing. Maximal isometric force (Fiso ) was obtained from IMTP, while mean force, mean velocity, jump height, and jump impulse (J) were gathered from SJ. To analyze the FVP, we calculated the linear relationship between force and velocity, which allowed us to obtain the slope of the relationship (SFV ), the theoretical velocity at zero force (V0 ), and the theoretical maximal power (Pmax ). DSI was obtained as a ratio from SJ peak force and Fiso . The convergent validity was investigated using Spearman's ρ coefficients to assess the relationships between jump height and J with Fiso , V0 , SFV , Pmax , and DSI. The intrasession reliability was assessed using intraclass correlation coefficients (ICC) and coefficient of variations (CV). All variables demonstrated acceptable reliability scores. ICC ranged from moderate to excellent, and the mean CV was <10%. We found a "very large" correlation between jump J and Pmax , while jump height was not correlated with any variable. In conclusion, the IMTP and SJ combination is a practical way to determine FVP producing capacities that can be reliably measured (intrasession). The Pmax , derived from FVP, was correlated with jump performance, which might evidence the convergent validity of the method.

• Klíčová slova
• Assessment, Dynamic strength index, Isometric midthigh pull, Linear regression, Performance, Squat jump, Two-point method,
• MeSH
• biomechanika * MeSH
• cvičení * MeSH
• dospělí MeSH
• lidé MeSH
• pohyb * MeSH
• reprodukovatelnost výsledků MeSH
• stehno fyziologie   MeSH
• Check Tag
• dospělí MeSH
• lidé MeSH
• mužské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH

Noninvasive polygraphic tracings obtained at rest and during isometric hand-grip exercise were analysed in 67 healthy subjects. The purpose of the study was to determine the response of noninvasive polygraphic parameters to isometric exercise. During the third minute of sustained squeezing of a balloon dynamometer (30% of maximal voluntary contraction) a significant increase occurred in heart rate (+16.8 +/- 10.7 beats/min) an increase in both systolic and diastolic blood pressure (+3.4 +/- 1.6 kPa and 2.6 +/- 1.7 kPa respectively), increase in apexcardiographic index 100.a/D (+14.5 +/- 15.0% "D" amplitude), decrease of diastolic amplitude time index square root 2-c/(2-0) X (a/D) (-20.1 +/- 26.5), shortening of pulse transmission time (-0.006 +/- 0.005 s) and prolongation of cardiac cycle length corrected for left ventricular ejection time (+0.011 +/- 0.010 s) discussed. All these changes were statistically significant.

• MeSH
• dospělí MeSH
• elektrokardiografie MeSH
• hemodynamika * MeSH
• isometrická kontrakce * MeSH
• kinetokardiografie MeSH
• krevní tlak MeSH
• lidé MeSH
• ruka * MeSH
• srdeční frekvence MeSH
• svalová kontrakce * MeSH
• tepový objem MeSH
• Check Tag
• dospělí MeSH
• lidé MeSH
• mužské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH

• MeSH
• dospělí MeSH
• elektroencefalografie * MeSH
• isometrická kontrakce * MeSH
• lidé MeSH
• motorické dovednosti fyziologie   MeSH
• mozková kůra fyziologie   MeSH
• ruka inervace   MeSH
• somatosenzorické evokované potenciály MeSH
• svalová kontrakce * MeSH
• Check Tag
• dospělí MeSH
• lidé MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH

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 purpose of the study was to evaluate non-invasively the response of the isovolumic relaxation period to different types of exercise--dynamic supine bicycle exercise (DSBE) and handgrip (HGP), in a selected healthy population. From simultaneous echo-polygraphic recordings, obtained in 30 young subjects at rest, during submaximal DSBE, during one minute of HGP (75% of maximal heart rate) and in the recovery period, the true isovolumic relaxation period (IRP) was determined. Systolic (SBP) and diastolic (DBP) blood pressure, aortic closing pressure (AoCP) and heart rate (HR) were also recorded. HR increased more markedly in DSBE (delta HR = +85% at peak load) than in HGP (delta HR = +29% at peak), while a greater rise of DBP (delta DBP = +25%) was observed in HGP. IRP shortened at both exercises as the workload progressively increased, with a maximum decrease by 54% in DSBE and by 42% in HGP. Moreover, at both exercises, an exponential correlation between IRP and HR was found. Correlating IRP with HR and AoCP by multiple regression analysis, it was found that IHP in HGP was equally affected by HR and AoCP, while during DSBE heart rate had a greater influence than AoCP.

• MeSH
• dospělí MeSH
• isometrická kontrakce * MeSH
• kontrakce myokardu * MeSH
• lidé MeSH
• mladiství MeSH
• svalová kontrakce * MeSH
• zátěžový test * MeSH
• Check Tag
• dospělí MeSH
• lidé MeSH
• mladiství MeSH
• mužské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH

BACKGROUND: Considering the important roles of porphyrins in biological systems and their promising use in photodynamic therapy (PDT), the present work investigated the photophysical properties of palladium(II) 5,10,15,20-tetrakis-(4-sulfonatophenyl)-porphyrin (PdTSPP) and the effects of non-activated by light form of this porphyrin on contractile behaviour of isolated healthy endothelium-denuded human mesenteric arteries. METHODS: The photophysical characterisation of PdTSPP: the formation of the triplet states and the singlet oxygen were studied using laser flash photolysis. The effect of PdTSPP on the isometric contraction of artery segments from human mesentery was assessed utilising the precise method of artery isometric tension recording using Mulvany-Halpern wire myograph. RESULTS: We found that PdTSPP had a high lifetime of the triplet states τT=270μs. The calculated Stern Volmer rate constant kq=1.7×10(9)M(-1)s(-1) showed an efficient quenching by oxygen that indicated formation of singlet oxygen, O2((1)Δg). The photophysical parameters of PdTSPP, in particular its ability to generate O2((1)Δg) has defined it as an exceptionally interesting molecule for PDT. The results of the contraction study showed that PdTSPP applied in increasing concentrations (1-100μM) had no effect on the basal tone of human mesenteric artery under isometric condition. Furthermore, PdTSPP failed to potentiate or to attenuate the isometric contraction of the artery preparations precontracted with high extracellular potassium (42mM KCl) or with 1nM endothelin-1. CONCLUSIONS: The excellent photophysical properties of PdTSPP as well as the lack of an effect on the contractility of human vasculature in vitro characterise PdTSPP as a suitable compound for potential medical applications.

• Klíčová slova
• Human mesenteric artery, Isometric contraction, Laser kinetics, Palladium(II) 5,10,15,20-tetrakis-(4-sulfonatophenyl)-porphyrin, Photophysical properties,
• MeSH
• arteriae mesentericae účinky léků   fyziologie   MeSH
• cévní rezistence účinky léků   fyziologie   MeSH
• dospělí MeSH
• fotochemoterapie metody   MeSH
• hladké svalstvo účinky léků   fyziologie   MeSH
• isometrická kontrakce účinky léků   fyziologie   MeSH
• lidé středního věku MeSH
• lidé MeSH
• porfyriny aplikace a dávkování   MeSH
• radiosenzibilizující látky aplikace a dávkování   MeSH
• senioři nad 80 let MeSH
• senioři MeSH
• techniky in vitro MeSH
• vztah mezi dávkou a účinkem léčiva MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• senioři nad 80 let MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• 5,10,15,20-tetrakis(4-sulfonatophenyl)-21,23-dithiaporphyrin MeSH Prohlížeč
• porfyriny MeSH
• radiosenzibilizující látky MeSH

100 rats were randomly divided into a sham-operated group and middle cerebral artery occlusion (MCAO) modeling groups. The sham group after surgery was observed for 14 days. After MCAO, some rats received isometric contraction training (ICT) which was as follows: an atraumatic tourniquet was placed around left or right hind limb to achieve hind limb ischemia for 5 min, followed by 5 min of reperfusion, 4 cycles for one time, once a day, and five days per week. The MCAO modeling groups included the following four groups: i) a group only received MCAO, and was observed for seven days (MCAO-7d), ii) a group only received MCAO, and was observed for 14 days (MCAO-14d), iii) a group, after MCAO, received ICT for seven days (ICT-7d), and iv) a group, after MCAO, received ICT for 14 days (ICT-14d). Brain infarct area, behavioral outcomes, the number of neurons, apoptosis, cerebral edema and cerebral water content were assessed, respectively. The mRNA expression of vascular endothelial growth factor (VEGF) was assayed with RT-PCR, and protein expression of VEGF was quantified with western blot. compared with MCAO controls, cerebral infarction, neurological deficits and neuronal apoptosis were reduced significantly in the ICT groups, while the number of neurons was increased. Moreover, the mRNA expression of VEGF and protein expression of VEGF were enhanced after 1 and 2 weeks of ICT. ICT may promote angiogenesis and neuroprotection after ischemic stroke and this new remodeling method provide a novel strategy for rehabilitation of stroke patients.

• MeSH
• cévní mozková příhoda * terapie   MeSH
• infarkt arteria cerebri media MeSH
• ischemie mozku * metabolismus   MeSH
• isometrická kontrakce * MeSH
• kondiční příprava zvířat * MeSH
• krysa rodu Rattus MeSH
• messenger RNA MeSH
• modely nemocí na zvířatech MeSH
• neuroprotekce MeSH
• potkani Sprague-Dawley MeSH
• vaskulární endoteliální růstový faktor A metabolismus   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• messenger RNA MeSH
• vaskulární endoteliální růstový faktor A MeSH

BACKGROUND: The study aimed to assess the acute effects of overcoming isometric split squats on subsequent single-leg drop jump (DJ) performance and the contralateral effect in volleyball players, considering training status differences. METHODS: Ten male elite (ELI) and ten amateur (AMA) volleyball players took part in two experimental sessions in which they performed conditioning activity (CA) consisted of 3 sets of overcoming isometric 3-second split squats, differing in the limb used: dominant (DL) or non-dominant (ND-L). Single-leg DJ was performed before and at the 4th and 8th minute post-CA for both limbs. The best post-CA attempt in terms of jump height (JH) was analyzed. RESULTS: Results revealed a significant increase in jump height (JH) in the non-dominant limb (ND-L) from 13.7 ± 2.6 cm to 15.5 ± 2.7 cm after CA performed by the ND-L (p = 0.001; Hedge's g = 0.65). Similarly, the reactive strength index (RSI) of the ND-L improved from 0.40 ± 0.06 to 0.45 ± 0.08 (p = 0.008; g = 0.58). Additionally, contact time in the ND-L increased significantly from 342 ± 36 ms to 375 ± 42 ms after CA performed by the dominant limb (p = 0.001; g = 0.66). In the elite (ELI) group, JH significantly increased from 16.4 ± 2.4 cm to 18.3 ± 3.3 cm (p < 0.001; g = 0.79), while RSI in the dominant limb (DL) improved from 0.47 ± 0.06 to 0.53 ± 0.07 (p = 0.011; g = 0.68). CONCLUSIONS: Results suggest that the examined CA effectively induces the post-activation performance enhancement in DJ among elite volleyball players, with a predominantly local impact on the limb executing the CA. TRIAL REGISTRATION: NCT06459050 (Retrospectively registered).

• Klíčová slova
• Explosive strength, Isometric exercise, Neuromuscular performance, Plyometric training, Post-activation potentiation, Unilateral movement,
• Publikační typ
• časopisecké články MeSH

The effectiveness of isometric conditioning activity (CA) is not well described in terms of the level of performance enhancement and the presence of a stretch and shortening cycle in subsequent explosive tasks. Therefore, the aim of this study was to evaluate the effect of a maximum isometric squat as the CA and a subsequent squat jump (SJ) and countermovement jump (CMJ) height. A total of 31 semi-professional handball and soccer players were randomly assigned to two different conditions: (i) 3 sets of 3 repetitions (each lasting 3 s) of maximum isometric back squats (EXP), and (ii) no CA (CTRL). The jump height measurements were performed 5 min before the CA and approximately at the 4th and 8th minute following the completion of the CA. Due to the high inter-individual variability in the potentiation responses, the best value obtained post-CA was also analyzed. The SJ height significantly increased from baseline to the 8th minute post-CA (p = 0.004; ES = 0.31; Δ = +3.1 ± 5.0%) in the EXP condition. On the other hand, the CMJ height was significantly higher in the 4th (p = 0.001; ES = 0.23; Δ = +2.7 ± 3.7%) and 8th minute post-CA (p = 0.005; ES = 0.32; Δ = +3.6 ± 5.7%) in comparison to baseline during the EXP condition. Furthermore, SJ height significantly increased from baseline to the best time-point during the EXP (p < 0.001; ES = 0.47; Δ = +4.9 ± 4.9%) and CTRL (p = 0.038; ES = 0.21; Δ = +2.5 ± 5.8%) condition. Moreover, the CMJ height was significantly higher at the best time-points than at the baseline during EXP (p < 0.001; ES = 0.53; Δ = +5.6 ± 4.7%) and CTRL (p = 0.002; ES = 0.38; Δ = +3.1 ± 5.2%) condition. The findings from this study indicate that a maximum isometric squat, used as a CA, effectively improved SJ and CMJ height. This suggests that the presence or absence of a stretch and shortening cycle in both CA and post-CA tasks does not significantly impact the post-activation performance enhancement response.

• Klíčová slova
• PAPE, complex training, countermovement jump, post-activation potentiation, squat jump,
• MeSH
• fotbal * MeSH
• lidé MeSH
• postura těla MeSH
• sporty * MeSH
• svalová síla fyziologie   MeSH
• tělesná výška MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH