The growth in the prevalence of myopia leads to the growth of socioeconomic stress in society. It is important to detect any potential risk factors leading to myopia onset and progression. Among the potential risk factors, the lack of natural daylight exposure and the lack of the physical activity together with excess of near-work activities in children are the most prevalent. In the study, the axial length growth depending on the season and the type of behaviour was measured. The assessment was performed in 12-year-old children, 398 eyes of whom were included and measured during the winter and summer period. The children were categorized by the amount of time spent on near-work, physical, and outdoor activity. Results. Statistically significantly higher (p < 0.0001) axial length growth was observed during the winter period. Statistically significantly (p < 0.0001) more frequently, the eyeball growth has been proved during the winter season. According to the way of spending leisure time, no statistically significant difference was reported within the individual subgroups in the development of the eyeball length during the observed period. However, statistically significant differences were ascertained in the eyeball initial length within various groups. Conclusion. The lack of daylight exposure may lead to myopia progression.

The aim of the study was to assess the effects of resistance training with the use of a suspension system on exercise tolerance, evaluated through an exercise test, and the changes in selected echocardiographic parameters of patients after myocardial infarction. The study involved 44 males. The subjects were divided into two groups: Standard (20) and Suspension system (24). All the subjects had undergone an angioplasty with stent implantation. The standard and suspension system groups carried out a 24-day improvement program comprising 22 training units. Each session consisted of endurance, general stamina and resistance training. Instead of resistance training, the experimental group made multijoint exercises with a suspension system. Statistically significant changes in both groups were observed in the parameters of the echocardiographic exercise test, such as test duration (p = 0.000), distance covered (p = 0.000), MET (p = 0.000), VO2max (p = 0.000) and SBPrest (p = 0.013). Additionally, SBPmax in the suspension system group improved (p = 0.035). The echocardiographic test revealed significant improvement of Left Ventricular Ejection Fraction in both groups (SP group p = 0.001, standard group p = 0.005). The lipid profile test in the SP group revealed statistically significant improvement of TC (p = 0.003), HDL (p = 0.000) and LDL (p = 0.005). Training with the suspension system had a positive effect on the change of exercise tolerance level, left ventricular function and blood lipid profile.

Východiska: Pravidelná pohybová aktivita (PA) se jeví jako nejúčinnější faktor prevence proti civilizačním onemocněním. Období adolescence je považováno za jedno z klíčových při tvorbě a udržení správného návyku k pravidelné PA. Domníváme se, že úroveň pohybové aktivity mládeže je možné ovlivnit možností vykonávat preferované sportovní aktivity. Cíle: Hlavním cílem studie bylo, na základě zjištění celkového objemu vykonané PA a struktury sportovních preferencí u západočeských adolescentů zjistit, zda existují vztahy mezi preferovanými sportovními odvětvími a skladbou a úrovní týdenní pohybové aktivity. Metodika: Výzkum byl realizován na pěti vybraných středních školách Plzeňského kraje, přičemž se ho celkově zúčastnilo 382 chlapců a 529 děvčat. Úroveň PA a sportovních preferencí byla zjišťována pomocí dotazníku IPAQ a Dotazníku sportovních preferencí s využitím internetového systému INDARES. Ke statistickému zpracování dat byla využita Kruskal-Wallisova ANOVA, kontingenční tabulky a Spearmanova korelační analýza. Výsledky: Výsledky ukázaly, že preference kondičních aktivit jsou ve významném vztahu s vyšší úrovní PA ve volném čase u chlapců (p = 0,006) a s intenzivní PA u chlapců (p = 0,014) i děvčat (p = 0,044) oproti těm, kteří tyto aktivity nepreferují. U chlapců jsme zjistili statisticky význam-né závislosti (p = 0,022) mezi preferencí týmových sportů a PA ve škole. 51,8 % chlapců a 37,7 % děvčat preferujících kondiční aktivity plní doporučení 3 × 20 min intenzivní PA během jednoho týdne (z nepreferujících pouze 30,5 % chlapců a 18,1 % děvčat). Hlavní preferované pohybové aktivity dívek jsou individuální sporty (plavání, cyklistika, sjezdové lyžování), následují pak týmové sporty a rytmické a taneční aktivity. U chlapců se na předních místech objevují týmové sporty (fotbal, florbal, basketbal), individuální sporty a kondiční aktivity. Závěry: Plnění cílů školní tělesné výchovy s co nejvíce možným využitím preferovaných sportovních aktivit považujeme za zá-sadní pro udržení či zlepšení vztahu adolescentů k tělesné výchově jako vyučovacímu předmětu a pro prevalenci pohybově aktivního životního stylu mládeže.Klíčová slova: pohlaví, IPAQ, Dotazník sportovních preferencí, škola, tělesná výchova * Korespondenční adresa: Petr Valach, Katedra tělesné a sportovní výchovy, Fakulta pedagogická, Západočeská univerzita v Plzni, Klatovská 51, 301 00 Plzeň, Česká republika. E-mail: pvalach@ktv.zcu.cz ÚvodPohybová aktivita (PA) a zdraví jsou jedny z nejfrekventovanějších termínů v kinantropologii. Zejména v dětství a dospívání je pravidelná PA nezbytná pro zdravý vývoj kosterního systému a funkčnosti svalového aparátu (Sigmud & Sigmundová, 2011). Mnoho autorů (Ainsworth & Tudor-Lock, 2005;Bouchard, Blair, & Haskell, 2007;Dong-Hyun & Wi-Young, 2012;Goldfield et al., 2011) se ve svých studiích shodně věnují i PA adolescentů a shodují se, že PA je jedním z nejzávažnějších faktorů při řešení otázek prevence a veřejného zdraví. Období adolescence se podle nich jeví jako nejvíce rizikové, protože v něm zaznamenávají největší pokle...

Post-activation potentiation (PAP) is a phenomenon which can improve force performance executed after a previous conditioning activity. PAP is usually evoked through heavy resistance, but many new methods are being suggested that acutely improve performance in post-activation potentiation protocols. The purpose of this study was to examine the effect of simultaneous application of Smith machine back squats (BS) with electromyostimulation (EMS) on sprint performance. Sixteen male (age = 22.9 ± 2.3 years, body mass = 79.9 ± 13.8 kg, BS one-repetition maximum (1 RM) = 120.5 ± 17.3) amateur football and rugby players volunteered for this study. Participants randomly performed PAP protocols (CON = no load, BS = 3 × 85% of 1 RM BS, EMS = 3 × weightless squat with electric current and BS + EMS = 3 × 85% 1 RM BS with electric current) on four different days with at least 48 h intervals. Participants rested passively for 7 min after preloads and performed the 30 m sprint test. Sprint times for 10 and 30 m were recorded for each condition. As a result, no significant difference was found in the 10 m (p = 0.13) and 30 m (p = 0.10) sprint performance between the preload protocols. The effect size was found to be trivial (ηp2: 0.13 for 10 m; ηp2: 0.11 for 30 m). In individual results, the 10 m sprint performance of five participants and 30 m sprint performance of two participants decreased in BS, EMS, or BS + EMS conditions compared with CON. No PAP effect in other participants was observed. In conclusion, preloads did not affect 10 m and 30 m sprint performance of football and rugby players. It can be said that the applied PAP protocols or physical exertion alone may cause fatigue in some individuals.

The purpose of this study was to determine the impact of a 30 min nap (N30) on the Running-Based Anaerobic Sprint Test (RAST) both during and after Ramadan. Ten physically active kickboxers (age: 21.20 ± 1.61 years, height: 174.80 ± 4.34 cm, body mass: 73.30 ± 7.10 kg and body mass index (BMI): 24.00 ± 2.21 kg/m2) voluntarily performed the RAST test after an N30 and in a no-nap condition (NN) during two experimental periods: the last ten days of Ramadan (DR) and ∼3 weeks after Ramadan (AR). During each DR-NN, DR-N30, AR-NN and AR-N30 protocol, kickboxers performed RAST performance. A statistically significant difference was found between Ramadan periods (DR vs. AR) in terms of max power (W) (F = 80.93; p1 < 0.001; η2p = 0.89), minimum power (W) (F = 49.05; p1 < 0.001; η2p = 0.84), average power (W) (F = 83.79; p1 < 0.001; η2p = 0.90) and fatigue index (%) results (F = 11.25; p1 = 0.008; η2p = 0.55). In addition, the nap factor was statistically significant in terms of the max power (W) (F = 81.89; p2 < 0.001; η2p = 0.90), minimum power (W) (F = 80.37; p2 < 0.001; η2p = 0.89), average power (W) (F = 108.41; p2 < 0.001; η2p = 0.92) and fatigue index (%) results (F = 16.14; p2 = 0.003; η2p = 0.64). Taking a daytime nap benefits subsequent performance in RAST. The benefits of napping were greater after an N30 opportunity for DR and AR.

In recent decades, the prevalence of myopia has increased worldwide as well as in European countries, and it has become an important medical and socioeconomic problem. Our prospective single-center study analysed the changes in ocular axial length (AXL) in a population of Central European schoolchildren from 2016 to 2019. The study included 528 eyes of 264 children with a mean age of 12.2 years at the beginning of the study. Visual acuity, ocular AXL, anterior chamber depth, and the questionnaire were examined at 6-month intervals (in spring and autumn, following the winter and summer periods, respectively). The average ocular AXL was 23.329 mm (median: 23.315 mm) at the beginning of the study and 23.525 mm (median: 23.505 mm) at the end of the study. The change in ocular AXL per month was significantly higher ( p < 0.0001 ) during the winter period (average: 0.013 mm, median: 0.011 mm) than during the summer period (average: −0.001 mm, median: 0.000 mm). We observed a significantly higher increase in ocular AXL in a Caucasian population during the winter period (with lower daylight exposure) than the summer period.

The individual, the same as a bio-psycho-social unit, is influenced by a number of exogenous factors influencing his/her development. In our investigation, we compared the physical condition of 6 to 8 year old children from selected primary schools in Pilsen. According to the regional location of a school within the Pilsen -City district, we determined only two categories of social status, namely the socially powerful and socially underprivileged groups. The socially powerful group consisted of 197 children (n = 197), and the underprivileged group consisted of 66 children (n = 66). Their physical condition was tested using the German test battery DMT6-18 (Bös). The Mann-Whitney test was used to compare data. Statistically significant differences (α ≤ 0.01) were found both in the level of somatic prerequisites (body height and weight), and in the results of all tests, with the exception of the deep forward bend bent test and Walking backwards on a beam with a diameter of 3 cm. The performances of children were similar in this particular tests.

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