Drugs are bioactive compounds originally discovered from chemical structures present in both the plant and animal kingdoms. These have the ability to interact with molecules found in our body, blocking them, activating them, or increasing or decreasing their levels. Their actions have allowed us to cure diseases and improve our state of health, which has led us to increase the longevity of our species. Among the molecules with pharmacological activity produced by plants are the polyphenols. These, due to their molecular structure, as drugs, also have the ability to interact with molecules in our body, presenting various pharmacological properties. In addition, these compounds are found in multiple foods in our diet. In this review, we focused on discussing the bioavailability of these compounds when we ingested them through diet and the specific mechanisms of action of polyphenols, focusing on studies carried out in vitro, in animals and in humans over the last five years. Knowing which foods have these pharmacological activities could allow us to prevent and aid as concomitant treatment against various pathologies.

Background and Objectives: Skeletal muscles are considered to be the main source of circulating irisin, both at rest and during physical activity. The aim of this study was to investigate the connection between irisin, body composition, and energy metabolism in humans. Materials and Methods: Serum irisin concentrations before and after acute aerobic exercise on a treadmill in 84 healthy adults were measured and their association with body composition and energy expenditure (EE) (obtained from indirect calorimetry) was determined. Results: The total pre-exercise irisin concentrations in males and females were similar, but higher in females when expressed per body mass kg (p < 0.001). There was an association between pre-exercise irisin per body mass kg, visceral fat rating (rho = −0.52, p = 0.001), and lean tissue % (rho = 0.41, p < 0.05) in males and lean body mass index (LBMI) (rho = −0.59, p < 0.001) in females. The pre-exercise irisin concentration correlated with the resting metabolic rate (RMR) in both sexes (rho = 0.44 in males, rho = 0.36 in females; p < 0.05), but with walking, running, and the EE difference from RMR in running (Δ running EE) in males only (rho = 0.32 to 0.37, p < 0.05). There was no significant change in irisin concentration after exercise in 58% of participants, while it decreased in 23%, and increased in 19%. In male subjects with no change in irisin concentration after exercise, running (p < 0.05) and Δ running EE per body mass kg (p < 0.05) were higher than in those with decreased irisin concentration. Conclusions: These findings indicate that the association of irisin concentration with body composition and EE parameters has sex-dependent differences, and acute exercise can lead to various changes in post-exercise irisin levels.

The most recent WHO recommendations about physical activity emphasise the importance of total exercise volume above the significance of the duration of each bout. This study examined whether acute aerobic exercise changes circulating levels of IL-8 and MCP-1 and if these changes are associated with body composition and energy metabolism. Healthy adult volunteers completed a 10 min walking–running exercise on a treadmill. Indirect calorimetry was used to determine their resting metabolic rate (RMR) and energy expenditure (EE) during the exercise. Pre-exercise levels of IL-8 and MCP-1 were similar in both sexes. There were positive correlations of pre-exercise IL-8 with body mass, waist circumference, and lean body mass in men and pre-exercise MCP-1 with RMR in women. The exercise led to an increase in IL-8 of 68% and a decrease in MCP-1 of 74% of participants. An increase in post-exercise IL-8 in men was associated with greater walking EE and a greater increase in walking EE. The increase in post-exercise MCP-1 was associated with a lower RMR and running EE in women. There are both sex and individual variations in changes in chemokine secretion in response to the same exercise situation and their associations with values of metabolic parameters.

It is important to integrate knowledge about the need for physical activities (PA) in the prevention and care of human health in nursing study programs so that nurses can promote PA among their patients. This study aims to evaluate the PA habits of Latvian nursing students. Participants were students of three universities in Latvia who were enrolled in a four-year bachelor study program, “Nursing”, with a total of 341 after the data cleaning (population size n = 1554). The questionnaire contained questions about sociodemographic variables derived from the survey of the Centre for Disease Prevention and Control of Latvia “Health Behaviour among Latvian Adult Population”, habits of PA, and International Physical Activity Questionnaire-Short Form. The data were collected between September and November 2021. Both descriptive and inferential statistics (difference between groups, correlation, and association tests) were calculated to analyse the data. Of the study population, 39% did not reach the minimum WHO-recommended PA. Increased PA level in the later study years is related to more frequent engagement in work and fewer table activities in the curriculum study process, but the higher intensity and total PA could be related to the specifics of nurse and nurse assistant work, which could be especially intense due to the overloaded health care system during the COVID-19 pandemic.

An adequate amount of physical activity (PA) in adults improves cardio-respiratory fitness, metabolic health and helps maintain a normal body weight and composition. Here we examined sex- and occupation-related PA patterns and their association with body composition parameters. Healthy volunteers (n = 97) aged 21–49 years completed a self-administered PA questionnaire and characterized their occupational duties depending on the volume of the physical work involved. A bio-impedance analyser was used to determine body composition. Men reported more metabolic equivalent of task (MET) minutes/week of vigorous PA than women (p < 0.05). Participants with low occupational PA had less walking, moderate and total MET minutes/week, and more sitting time than those with moderate and vigorous occupational PA (p < 0.05), but their body composition parameters did not differ. In males, negative correlations were found between body fat percentage, visceral fat range, segmental fat mass, and moderate MET minutes/week, whereas positive associations were observed between muscle mass in legs and vigorous MET minutes/week (p<0.05). In females, negative correlations were found between visceral fat and vigorous MET minutes/week but positive – between lean body mass, trunk and leg muscle mass, and moderate PA (p < 0.05). These observed associations might be used to develop interventions to promote sex- and occupation-specific PA.

The concept of metabolism pertains to the biochemical transformation reactions of substances that generate energy required for life processes. In this Thesis, with respect to the utilisation of energy-yielding compounds within the organism and the release of energy through metabolic processes, the term ‘energy metabolism’ will be applied. Research indicates that, over recent decades, there has been a decline in humans’ basal metabolic rate. This alteration is associated with the global rise in obesity-related health problems. A comprehensive understanding of the principles underpinning energy metabolism and the factors affecting it provides a foundation for elucidating the mechanisms involved in the onset of obesity and metabolic diseases, as well as for developing potential strategies to address these significant global health challenges. The regulation of metabolic processes is complex and multifactorial, involving anatomical, genetic, neural, humoral, and molecular components. The composition of body tissues, which is considerably influenced by physical activity, interacts dynamically with energy metabolism. This bidirectional relationship implies that changes in energy metabolism induce alterations in body composition and vice versa. Particular emphasis is placed on the role of factors secreted in response to physical exercise, referred to as exerkines, and their potential application as biomarkers or therapeutic agents. Although the impact of individual regulatory factors on energy utilisation may be modest in the short term, they may, over time, precipitate adaptive responses and notable shifts in human energy balance. Therefore, investigating energy metabolism within the holistic context of the organism facilitates observation and understanding of the integrative physiological mechanisms. Present knowledge regarding energy utilisation during physical exertion is largely derived from male cohorts, underscoring the necessity for incorporating females in future studies to enhance comprehension of sex-specific metabolic nuances. The primary objective of this study was to analyse the interrelationships between body composition, habitual physical activity, exerkine levels, and gene polymorphisms, and their associations with energy metabolism at rest and during acute physical exertion in healthy males and females. This quantitative, experimental, cross-sectional study recruited 99 healthy adults (44 males and 55 females), aged 20–50 years. Data collection methods included anthropometry, body composition analysis via bioelectrical impedance, assessment of habitual physical activity through questionnaire and combined heart rate and accelerometry monitoring, measurement of metabolic rate using indirect calorimetry at rest and during brief treadmill exercise, laboratory assays for exerkine quantification and gene variant determination, and application of statistical analyses for data interpretation. Findings revealed that over one-quarter of participants exhibited habitual physical activity (PA) below the recommended health guidelines; conversely, those achieving sufficient PA level demonstrated longer durations of moderate and vigorous intensity exercise. In males, PA correlated negatively with body mass index (BMI), muscle mass, and fat mass; notably, the duration of vigorous PA exhibited a negative association with fat mass, particularly in the legs. In females, total PA was inversely correlated with visceral adiposity, while prolonged low-intensity PA duration was associated with increased fat mass; moderate-intensity PA duration correlated positively with leg muscle mass. Resting metabolic rate (RMR), in kcal/kg/day displayed considerable interindividual variation and correlated positively with lean mass percentage and negatively with body mass, height (in males only), BMI, waist and hip circumferences, and total and visceral fat mass. In both sexes, walking energy expenditure was inversely associated with body mass; however, only in males were positive correlations observed between walking and running energy expenditure with lean mass, and negative correlations with BMI, waist and hip circumferences, and adiposity. Basal exerkine concentrations did not differ significantly between sexes; however, there were significant associations between irisin and interleukin-8 (IL-8) concentrations with age and body composition exclusively in males. Post-exercise alterations in exerkine levels exhibited substantial individual variability in both direction and magnitude. Mean irisin concentrations pre- and post-exercise test did not differ significantly; however, monocyte chemoattractant protein-1 (MCP-1) decreased and IL-8 increased significantly post-exercise (p < 0.05 in females only). Analyses of single nucleotide polymorphisms within ACE, ACTN3, and HIF1A genes revealed no significant associations with energy metabolism parameters in the cohort studied. Significant interrelations among resting and exercise energy metabolism, exerkine concentrations, body constitution, and tissue composition were identified solely in males; associations with habitual physical activity were observed in a subset of participants. In females, direct correlations with RMR were confined to body phenotype and tissue composition, with no statistically robust associations for other parameters. These findings highlight sex-specific variations in determinants of energy metabolism. The persistence of individual variability within the selected healthy adult cohort underscores the multifactorial nature of metabolic regulation and the necessity for measured values in case of individually tailored solutions. The Doctoral Thesis was developed at Department of Human Physiology and Biochemistry, Rīga Stradiņš University, Latvia. Defence of the Doctoral Thesis will take place at the public session of the Promotion Council of Basic Medicine on 30 March 2026, at 15.00 in the Hippocrates...