A method for evaluating the transport and energy conversion properties of polymer biomembranes using the Kedem-Katchalsky-Peusner equations.

BACKGROUND: A basic parameter in non-equilibrium thermodynamics is the production of entropy (S-entropy), which is a consequence of the irreversible processes of mass, charge, energy, and momentum transport in various systems. The product of S-entropy production and absolute temperature (T) is called the dissipation function and is a measure of energy dissipation in non-equilibrium processes. OBJECTIVES: This study aimed to estimate energy conversion in membrane transport processes of homogeneous non-electrolyte solutions. The stimulus version of the R, L, H, and P equations for the intensity of the entropy source achieved this purpose. MATERIAL AND METHODS: The transport parameters for aqueous glucose solutions through Nephrophan® and Ultra-Flo 145 dialyser® synthetic polymer biomembranes were experimentally determined. Kedem-Katchalsky-Peusner (KKP) formalism was used for binary solutions of non-electrolytes, with Peusner coefficients introduced. RESULTS: The R, L, H, and P versions of the equations for the S-energy dissipation were derived for the membrane systems based on the linear non-equilibrium Onsager and Peusner network thermodynamics. Using the equations for the S-energy and the energy conversion efficiency factor, equations for F-energy and U-energy were derived. The S-energy, F-energy and U-energy were calculated as functions of osmotic pressure difference using the equations obtained and presented as suitable graphs. CONCLUSIONS: The R, L, H, and P versions of the equations describing the dissipation function had the form of second-degree equations. Meanwhile, the S-energy characteristics had the form of second-degree curves located in the 1st and 2nd quadrants of the coordinate system. These findings indicate that the R, L, H, and P versions of S-energy, F-energy and U-energy are not equivalent for the Nephrophan® and Ultra-Flo 145 dialyser® membranes.

Body Loading during an Intensive Yoga Exercise Routine and a Cycle Ergometer Test.

The present study compared the effects on the cardiovascular, respiratory, and metabolic functions of the practice of an intensive yoga exercise routine called Dynamic Suryanamaskar (DSN) and a cycle ergometer test (CET) of increasing intensity. The study involved 18 middle-aged volunteers who had previously practiced DSN. The study was conducted in two series (i.e., as CET and DSN with similar intensity) until complete exhaustion. At rest (R), at the ventilatory anaerobic threshold (VAT), and at the maximum workload (ML), the variables characterizing cardiovascular, respiratory, and metabolic functions were determined. In addition, the subjective intensity of both efforts was determined using the Borg test. No functional differences were observed in the cardiovascular, respiratory, and metabolic systems at similar CET and DSN intensities. Respondents experienced less subjective workload during DSN than during CET (p < 0.001). Since DSN intensifies the activity of the cardiovascular, respiratory, and metabolic systems to a similar degree to CET both at VAT and ML, but causes less subjective fatigue, this yogic practice can be used as a laboratory exercise test and as an effective training medium.

Energy conversion in Textus Bioactiv Ag membrane dressings using Peusner's network thermodynamic descriptions.

BACKGROUND: The Textus Bioactiv Ag membrane is an active dressing for the treatment of chronic wounds such as venous stasis ulcers and burns. OBJECTIVES: Determination of the transport and internal energy conversion properties of the Textus Bioactiv Ag membrane using the Kedem-Katchalsky-Peusner model. This model introduces the coefficients Lij necessary to calculate the degree of coupling (lij, QL), energy conversion efficiency (eij), dissipated energy (S-energy), free energy (F-energy), and internal energy (U-energy). MATERIAL AND METHODS: The research material was the Textus Bioactiv Ag membrane that is used as an active dressing in the treatment of difficult-to-heal wounds, and KCl aqueous solutions. The research methods employed Peusner's formalism of network thermodynamics and Kedem and Katchalsky's thermodynamics of membrane processes. To calculate the Lij coefficients, we used hydraulic conductivity (Lp), diffusion conductivity (u) and reflection (ó) coefficients to perform experimental measurements in different conditions. RESULTS: The Lp coefficient for the Textus Bioactiv Ag membrane is nonlinearly dependent on the average concentrations of the solutions. In turn, the u and ó coefficients are nonlinearly dependent on the differences in osmotic pressures (Äd). An increase in the Äd causes the Textus Bioactiv Ag membrane to become more permeable and less selective for KCl solutions. The coefficients of Peusner (Lij), couplings (lij, QL), energy conversion efficiency (eij), S-energy, F-energy, and U-energy also depend nonlinearly on Äd. Our results showed that for higher concentrations of KCl solutions transported through the Textus Bioactiv Ag membrane, the coupling and energy conversion coefficients were greater for larger Äd up to their maximum values for large Äd. Coupling of the membrane structure with the electrolyte flux through the membrane is observed for Äd greater than 10 kPa. CONCLUSIONS: Textus Bioactiv Ag membrane dressings possess the properties of a solution component separator as well as an internal energy converter.

The importance of the size of the trunk inclination angle in the early detection of scoliosis in children.

BACKGROUND: Early detection of idiopathic scoliosis is one factor in determining treatment effectiveness. Therefore, the aim of this study was to assess the importance of the size of the trunk inclination angle (ATI) for the early detection of scoliosis in preschool- and school-age children, taking into account the location and size of the spine curvature. METHODS: The study included a group of 216 children (mean age 11.54 years, standard deviation ± 3.05), who had previously untreated idiopathic scoliosis and a Cobb angle of ≥ 10°. The ATI values were compared with the corresponding Cobb angle values. The results of the ATI-Cobb correlation were compared to the ATI thresholds of 5° and 7°. RESULTS: In the age groups 6-9, 10-12 and 13-17 years, the method sensitivity for the ATI ≥ 7° criterion was low at 33.90%, 27.69% and 51.29% (p < 0.05), respectively, while for the ATI ≥ 5° criterion, it was 67.8%, 69.23% and 93.48% (p < 0.05), respectively. With respect to location, significantly more frequent misdiagnoses (p < 0.05) were related to the lumbar and thoracolumbar (regions) sections of the spine in the groups aged 6-9 and 10-12 for ATI ≥ 7°; while no significant relationship was found at ATI ≥ 5°. For both ATI levels, the most frequent cases of mis- or undiagnosed scoliosis were observed among children with a Cobb angle of 10°-14° (p = 0.004). CONCLUSION: A low predictive ATI value was demonstrated regarding scoliosis detection for the ATI 7° criterion in children aged 6-9 and 10-12 years, particularly for the lumbar and thoracolumbar locations. Adoption of the threshold of ATI 5° in screening tests for children aged 6-12 years, as well as for lower locations of scoliosis, may be more effective in the early detection of scoliosis. TRIAL REGISTRATION: This study was approved by the Jan Dlugosz University in Czestochowa Ethics Committee KE-U/7/2021, and conducted under the Declaration of Helsinki.

Indoor cycling training in rehabilitation of patients after myocardial infarction.

BACKGROUND: Standard endurance training used from the second stage of cardiac rehabilitation has many common features with indoor cycling training which is used in fitness clubs. In the study, an attempt was made to evaluate the usefulness of this form of training in a 24-day rehabilitation program for patients after myocardial infarction. The study examined a group of 64 patients (51.34 ± 8.02 years) who were divided into two groups: the IC group (32 patients aged 53.40 ± 4.31 years) with indoor cycling training instead of standard endurance training; and the ST group (32 patients aged 55.31 ± 6.45 years) performing standard training. The level of exercise tolerance (cardiopulmonary exercise testing on a treadmill-Bruce's protocol), hemodynamic indicators of the left ventricle (echocardiography) and blood lipid profile (laboratory test) were assessed. RESULTS: In the IC group there was a significant increase in the test duration (9.21 ± 2.02 vs 11.24 ± 1.26 min; p < 0.001), the MET value (9.16 ± 1.30 vs 10.73 ± 1.23; p = 0.006) and VO2max (37.27 ± 3.23 vs 39.10 ± 3.17 ml/kg/min; p < 0.001). Parallel changes were observed in the ST group, where the following parameters improved: the test duration (9.41 ± 0.39 vs 10.91 ± 2.22; p < 0.001), MET value (8.65 ± 0.25 vs 9.86 ± 1.12; p = 0.002) and VO2max (36.89 ± 6.22 vs 38.76 ± 3.44; p < 0.001). No statistically significant changes were found in the hemodynamic indices of the left ventricle and the lipid profile. Also, the intergroup analysis did not show any statistical significance. CONCLUSION: Based on the research results, it was found that indoor cycling training in the second phase of cardiac rehabilitation is a safe form of therapy and therefore may be an interesting alternative method to the classic bicycle ergometer exercise in the stage of early cardiac rehabilitation.

The Use of Artificial Hypoxia in Endurance Training in Patients after Myocardial Infarction.

The presence of a well-developed collateral circulation in the area of the artery responsible for the infarction improves the prognosis of patients and leads to a smaller area of infarction. One of the factors influencing the formation of collateral circulation is hypoxia, which induces angiogenesis and arteriogenesis, which in turn cause the formation of new vessels. The aim of this study was to assess the effect of endurance training conducted under normobaric hypoxia in patients after myocardial infarction at the level of exercise tolerance and hemodynamic parameters of the left ventricle. Thirty-five patients aged 43-74 (60.48 ± 4.36) years who underwent angioplasty with stent implantation were examined. The program included 21 training units lasting about 90 min. A statistically significant improvement in exercise tolerance assessed with the cardiopulmonary exercise test (CPET) was observed: test duration (p < 0.001), distance covered (p < 0.001), HRmax (p = 0.039), maximal systolic blood pressure (SBPmax) (p = 0.044), peak minute ventilation (VE) (p = 0.004) and breathing frequency (BF) (p = 0.044). Favorable changes in left ventricular hemodynamic parameters were found for left ventricular end-diastolic dimension LVEDD (p = 0.002), left ventricular end-systolic dimension LVESD (p = 0.015), left ventricular ejection fraction (LVEF) (p = 0.021), lateral e' (p < 0.001), septal e' (p = 0.001), and E/A (p = 0.047). Endurance training conducted in hypoxic conditions has a positive effect on exercise tolerance and the hemodynamic indicators of the left ventricle.

Eight Days of Water-Only Fasting Promotes Favorable Changes in the Functioning of the Urogenital System of Middle-Aged Healthy Men.

The aim of this study was to determine whether, after 8 days of water-only fasting, there are changes in the efficiency of the lower urinary tract, the concentration of sex hormones, and the symptoms of prostate diseases in a group of middle-aged men (n = 14). For this purpose, before and after 8 days of water-only fasting (subjects drank ad libitum moderately mineralized water), and the following somatic and blood concentration measurements were made: total prostate specific antigen (PSA-T), free prostate specific antigen (PSA-F), follicle stimulating hormone (FSH), luteotropic hormone (LH), prolactin (Pr), total testosterone (T-T), free testosterone (T-F), dehydroepiandrosterone (DHEA), sex hormone globulin binding (SHGB), total cholesterol (Ch-T), ß-hydroxybutyrate (ß-HB). In addition, prostate volume (PV), volume of each testis (TV), total volume of both testes (TTV), maximal urinary flow rate (Qmax), and International Prostate Symptom Score (IPSS) values were determined. The results showed that after 8 days of water-only fasting, Qmax and IPSS improved but PV and TTV decreased significantly. There was also a decrease in blood levels of PSA-T, FSH, P, T-T, T-F, and DHEA, but SHGB concentration increased significantly. These results indicate that 8 days of water-only fasting improved lower urinary tract functions without negative health effects.

Body composition and nutrition of female athletes

Background: The somatic features of the athletes' bodies partially determine their sporting level and are conditioned to a large extent by the state of nutrition. Objective: The aim of this paper is to present nutritional status and its correlation with the somatic determinants of training athletes and physical education students. Material and methods: This study involved 12 weightlifting players (subgroup-WL), 15 soccer players (subgroup-SP), 12 table tennis players (subgroup-TT) and 12 female students of physical education (subgroup-C). In all subjects, the age and somatic variables were recorded and the daily intake of energy, water, proteins, fats and carbohydrates was determined by 24-h dietary recalls. Results: Although the analysis of variance did not show significant differences in somatic variables and nutrition data, post hoc analysis showed significant differences between some subgroups in terms of age, BMI, fat content (BF), fat-free mass (FFM) and the amount of water, protein and carbohydrates consumed during the day. It was also shown that somatic variables correlated with relatively expressed amounts of energy, proteins and carbohydrates consumed in individual subgroups, as well as in the whole group formed from all subgroups of studied women. In addition, there were significant correlations between somatic variables and the total amount of water consumed in the whole group and the total amount of protein consumed in subgroup C (p<0.05), as well as the total amount of fat consumed in subgroup WL. Conclusions: In summary, it was found that the examined women used an abnormal hypoenergetic diet with too low carbohydrate content in which were more useful relative than absolute amounts of consumed proteins, fats and carbohydrates. In this unfavorable situation, dietary education of the respondents seems to be necessary.

Three-Year Chronic Consumption of Low-Carbohydrate Diet Impairs Exercise Performance and Has a Small Unfavorable Effect on Lipid Profile in Middle-Aged Men.

The objective of this research was to determine whether chronic (average 3.58 ± 1.56 years) deliberate adherence to low carbohydrate diets (LCDs) is associated with selected markers of metabolism, risk factors of cardiovascular disease (CVD), body mass and physical performance in apparently healthy middle-aged men (n = 12). The control group comprised age, body mass and height matched men using mixed diets (MDs). The diets used were registered for 7 days and analyzed in terms of the energy, carbohydrate, fat and protein contents. It was found that the diets used were isoenergetic, yet varied considerably in carbohydrate and fat content. The LCDs significantly intensified the ketogenesis process, increased resting blood total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), and heart rate, (HR) and decreased respiratory exchange ratio (RER) in relation to MD subjects. An exercise trial revealed significant impairment of exercise in subjects following the LCDs. The results showed that in the case where the subjects of two investigated groups did not differ in their somatic variables, long-term adherence to the LCDs was associated with substantially reduced exercise performance in apparently healthy subjects, along with an association with a small unfavorable effect on their lipid profile.

A nutritional evaluation of dietary behaviour in various professional sports.

BACKGROUND: The types of physical exertion undertaken by weightlifters and race walkers markedly differ. This difference should also be reflected in their respective diets. OBJECTIVES: The aim of the study was to investigate and assess the diets of professional weightlifters and race walkers, along with a comparison to the diets of those students studying physical education (PE). Materials and Methods. Subjects were respectively 12 weightlifters, 12 race walkers and 12 physical education students whose body composition and nutrition were determined by weighing the foods that were both eaten and drunk. RESULTS: The study groups showed body differences, which may have arisen through dietary differences. Higher calorie diets were observed for race walkers according to body mass whilst weightlifters showed no difference with the other groups. Dietary intakes of protein, fat, and carbohydrates were however inappropriate for all groups. Vitamin and mineral intakes in weightlifters and students were within tolerable limits, but the rather aggressive taking of supplements by race walkers resulted in standard/recommended consumption levels being greatly exceeded in some cases. CONCLUSIONS: The diets of the study groups of weightlifters and race walkers need to be corrected. KEY WORDS: nutrition in sport, weightlifting, race walking, food supplementation.

Health benefits and risk associated with adopting a vegetarian diet.

A vegetarian diet may be adopted for various reasons that can include ecological, economic, religious, ethical and health considerations. In the latter case they arise from the desire to lose weight, in tackling obesity, improving physical fitness and/or in reducing the risk of acquiring certain diseases. It has been shown that properly applied vegetarian diet is the most effective way of reducing body mass (expressed as BMI), improving the plasma lipid profile and in decreasing the incidence of high arterial blood pressure, cardiovascular disease, stroke, metabolic syndrome and arteriosclerosis. In addition, improved insulin sensitivity together with lower rates of diabetes and cancer has been observed. Some studies have however found that a vegetarian diet may result in changes adversely affecting the body. These could include; hyperhomocysteinaemia, protein deficiency, anaemia, decreased creatinine content in muscles and menstrual disruption in women who undertake increased physical activity. Some of these changes may decrease the ability for performing activities that require physical effort. Nevertheless, on balance it can be reasonably concluded that the beneficial effects of a vegetarian diet significantly, by far, outweigh the adverse ones. It should also be noted that the term 'vegetarian diet' is not always clearly defined in the literature and it may include many dietary variations.

In aged men, central vessel transmural pressure is reduced by brief Valsalva manoeuvre during strength exercise.

A brief Valsalva manoeuvre, lasting 2-3 s, performed by young healthy men during strength exercise reduces transmural pressure acting on intrathoracic arteries. In this study, we sought to verify this finding in older men. Twenty normotensive, prehypertensive and moderately hypertensive otherwise healthy men 46-69 years old performed knee extensions combined with inspiration or with brief Valsalva manoeuvre performed at 10, 20 and 40 mmHg mouth pressure. Same respiratory manoeuvres were also performed at rest. Non-invasively measured blood pressure, knee angle, respiratory airflow and mouth pressure were continuously registered. In comparison to inspiration, estimated transmural pressure acting on thoracic arteries changed slightly and insignificantly during brief Valsalva manoeuvre at 10 and 20 mmHg mouth pressure. At 40 mmHg mouth pressure, transmural pressure declined at rest (-8·8 ± 11·4 mmHg) and during knee extension (-12·1 ± 11·9 mmHg). This decline ensued, as peak systolic pressure increase caused by this manoeuvre, was distinctly <40 mmHg. Only a main effect of mouth pressure was revealed (P<0·001) and neither exercise nor interaction between these factors, what suggests that transmural pressure decline, depended mainly on intrathoracic pressure developed during brief Valsalva manoeuvre. Resting blood pressure did not influence the effect of brief Valsalva manoeuvre on transmural pressure.