Miera stāvokļa un fiziskas slodzes enerģētisko metabolismu ietekmējošie faktori pieaugušajiem

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.