The effect of voluntary hypoventilation on physical performance and selected parameters of physiological function in athletes - a systematic review

Title: The effect of voluntary hypoventilation on physical performance and selected parameters of physiological function in athletes - a systematic review Objectives: The aim of this thesis is to summarize the results of selected studies dealing with voluntary hypoventilation technique and from the obtained data determine the possibility and extent of using this technique to improve sports performance. Methods: The bachelor thesis was conducted in the form of a systematic review, according to the recommendations of the PRISMA statement. Relevant scientific articles and studies were retrieved using four internet databases, namely Web of Science, Pub Med, Scopus and EBSCOhost, followed by literature research of the retrieved publications. Results: A total of 129 potential studies were retrieved from which 16 relevant publications were selected and included in the systematic review. In all cases, these were cohort studies, seven of them focused on investigating the acute response of hypoventilation training and nine on its long-term effect. Together, these studies collected data from 270 actively exercising probands. Conclusions: The results of selected scientific studies over the last twenty years suggest that hypoventilation training could be a beneficial and affordable training method to improve...Název: Vliv dobrovolné hypoventilace na výkon a vybrané ukazatele fyziologických funkcí u sportovců - přehledová studie Cíl: Cílem práce je shrnout výsledky vybraných studií zabývajících se technikou dobrovolné hypoventilace a ze získaných dat určit možnost a míru využití této techniky ke zlepšení sportovního výkonu. Metody: Bakalářská práce byla realizována formou přehledové studie, dle doporučení PRISMA statement. Relevantní vědecké články a studie byly vyhledávány pomocí čtyř internetových databází, konkrétně: Web of Science, Pub Med, Scopus a EBSCOhost a následným průzkumem literárních zdrojů vyhledaných publikací. Výsledky: Celkově bylo vyhledáno 129 potenciálních studií, ze kterých bylo vybráno 16 relevantních publikací, jež byly zařazeny do systematického přehledu. Ve všech případech se jednalo o kohortové studie, sedm z nich se zaměřovalo na zjišťování akutní odezvy hypoventilačního tréninku a devět na jeho dlouhodobý efekt. Tyto studie dohromady shromažďují data 270 aktivně sportujících probandů. Závěry: Výsledky vybraných vědeckých studií z posledních dvaceti let naznačují, že by hypoventilační trénink mohl být přínosnou a dostupnou tréninkovou metodou pro zlepšení sportovní výkonnosti a navození podobných efektů, jaké způsobuje expozice hypoxickému prostředí, na úrovni moře. Klíčová...Department of Biomedical Foundation in KinanthropologyKatedra biomedicínského základu v kinantropologiiFaculty of Physical Education and SportFakulta tělesné výchovy a sport

Influence of linear low density polyethylene on flow of recycled polyethylene

Práce se zabývá studiem reologických vlastností tavenin recyklovaného polyetylénu (rPE) a vlivem přídavku velmi nízko hustotního polyetylénu (LLD). Přídavek LLD, který se k rPE přidává za účelem úpravy indexu toku taveniny a zpracovatelských vlastností rPE, činil 5–20 %. K charakterizaci složení výchozího recyklátu byla použita metoda termogravimetrické analýzy a diferenční kompenzační kalorimetrie. Reologická měření byla provedena za použití geometrie deska-deska v módu oscilačním při deformaci 0,25 %, rozsahu frekvencí 0,01–100 Hz a teplotě 140, 170, 180 a 190 °C a v módu tokovém (smykovém) při teplotě 190 °C v rozsahu smykových rychlostí 0,001–100 1/s. Recyklovaný materiál byl složený z nízko hustotního polyetylénu a LLD v poměru asi 1 : 1 a obsahoval malé množství vápence a polypropylénu. Z oscilačních měření byla u rPE, směsí a čistých složek směsí vyhodnocována viskozita a smykový modul a posouzena změna mikrostruktury, molekulové hmotnosti a její distribuce. Ze smykového módu byla vyhodnocená stabilita tavenin v čase, nulová smyková viskozita a elasticita tavenin. Z obou módů byla vyhodnocena mísitelnost směsí. Bylo zjištěno, že přídavkem 5–15 % LLD se chování recyklátu postupně blíží chování čistého LLD, zatímco přídavek 20 % LLD nemá na reologické vlastnosti recyklátu vliv. Důvodem zde není změna v obsahu dlouhých a krátkých větví, ale specifická interakce makromolekul. Tento poznatek může v budoucnu usnadnit nastavení nejvhodnějších podmínek pro další zpracování rPE s ohledem na jeho složení.The work deals with the study of rheological behavior of recycled polyethylene (rPE) and the influence of linear low density polyethylene (LLD). The addition of LLD, which is added into rPE in order to set melt flow index and processing conditions, was 5–20 %. The received rPE was characterized by Thermogravimetry and Differential Scanning Calorimetry. Rheological measurements were performed on a reometer with plate-plate geometry in oscillatory mode (deformation of 0.25%, frequency range 0.01–100 Hz and temperature of 140, 170, 180 and 190 °C) and in flow mode (shear) at 190 °C and the shear rate 0,001–100 1/s. The recycled material contained low density polyethylene and LLD in a range approx. 1 : 1 and small amount of chalk and polypropylene. Complex viscosity and complex shear modulus together with their components were evaluated from oscillatory measurements of rPE, blends and neat polymer components. The change of microstructure, molecular weight and its distribution was evaluated as well. The melt stability in time was evaluated from flow measurements together with zero shear viscosity and melt elasticity. Miscibility of melt blends was evaluated from both type of measurements. It was found that the addition of 5–15% of LLD shifted rheological behavior of rPE into that of LLD but rheological behavior of the blend with the addition of 20% of LLD is the same as that of rPE. The reason is not different content of short and long branches but specific interaction of macromulecules. This knowledge may facilitate to set proper conditions of further processing of rPE regarding its composition.

Key factors of selected tensides used for full notch creep test of high density polyethylene

The thesis deals with the study of surface-active properties, zeta potential, particle size and adhesion of surfactants (Arkopal N110, Igepal CO-520, Igepal CO-890, Dehyton PL, sodium dodecyl sulfate and dodecyltrimethylammonium bromide) selected for full notch creep test method. To determine the surface phenomena occuring in a solution due to their presence at 25, 50 and 80 °C, the Du Noüy ring method of surface tension measurement was used. The importance of factors such as concentration, ionic character and the molecular structure of the surfactants, temperature and dispersion media (pH, purity) were analysed. Dynamic light scattering measurements were performed in order to evaluate the particle size and the electrophoresis method was used to determine the zeta potential. The results were compared to the contact angle measurements, i. e. adhesion tendency between surfactant solutions and the surface of selected types of high density polyethylene. The optical analysis was used to evaluate the contact angle. The negative impact of water purity was negated. The temperature dependecy was specific for each of the examined surfactant species, however the relationship between temperature and the length of hydrophilic chain was discovered. Alkaline pH was less convenient for amphoteric surfactant than acid or neutral environment, but this might have been caused by components contained in the buffer. The character of surfactant solutions was mostly monodisperse. The only exceptions were 1mM Igepal CO-520 and 3mM Dehyton PL. Further investigation led to conclusion that the molecules tend to form agglomerates. Adhesion was in accordance with surfactant effectiveness of surface reduction and adsorption. However, this theory did not match the data obtained from testing acid and neutral Dehyton PL solutions' adhering to polyethylene species containing carbon black

Influence of linear low density polyethylene on flow of recycled polyethylene

The work deals with the study of rheological behavior of recycled polyethylene (rPE) and the influence of linear low density polyethylene (LLD). The addition of LLD, which is added into rPE in order to set melt flow index and processing conditions, was 5–20 %. The received rPE was characterized by Thermogravimetry and Differential Scanning Calorimetry. Rheological measurements were performed on a reometer with plate-plate geometry in oscillatory mode (deformation of 0.25%, frequency range 0.01–100 Hz and temperature of 140, 170, 180 and 190 °C) and in flow mode (shear) at 190 °C and the shear rate 0,001–100 1/s. The recycled material contained low density polyethylene and LLD in a range approx. 1 : 1 and small amount of chalk and polypropylene. Complex viscosity and complex shear modulus together with their components were evaluated from oscillatory measurements of rPE, blends and neat polymer components. The change of microstructure, molecular weight and its distribution was evaluated as well. The melt stability in time was evaluated from flow measurements together with zero shear viscosity and melt elasticity. Miscibility of melt blends was evaluated from both type of measurements. It was found that the addition of 5–15% of LLD shifted rheological behavior of rPE into that of LLD but rheological behavior of the blend with the addition of 20% of LLD is the same as that of rPE. The reason is not different content of short and long branches but specific interaction of macromulecules. This knowledge may facilitate to set proper conditions of further processing of rPE regarding its composition