Obesity, physical activity and cardiorespiratory fitness in young adulthood : Studies in Finnish twins
Year: 2012
Type: dissertation
Study design: Observational Study
Abstract: Background: Obesity is one of the leading causes of ill-health in the Western world, and physical inactivity is a known risk factor for obesity. Obesity as well as physical activity and cardiorespiratory fitness are influenced by both genetic and environmental factors. However, whether they share the same genetic vs. environmental etiology has rarely been studied. Aims: To explore the relative contributions of genetic and environmental factors on body mass index (BMI), waist circumference, physical activity and cardiorespiratory fitness, to explore whether physical activity modifies the relative contribution of genetic factors on BMI and waist circumference and to assess the effects of obesity on cardiorespiratory fitness and expression of genes of mitochondrial oxidative phosphorylation in young adult twins. Subjects: 4,798 twins born in 1975 - 1979 (FinnTwin16 cohort) and followed up from the ages of 16 to 23 - 27 years; two subsamples of the FinnTwin16 cohort: one consisting of 24 monozygotic (MZ) pairs concordant and discordant for obesity and the other consisting of 152 MZ and DZ (dizygotic) twin pairs selected to represent a wide range of intra-pair differences in BMI; 1,294 twins born in 1983 - 1987 and followed up from the ages of 11 - 12 to 20 - 25 years (FinnTwin12 cohort). Measures: Cohorts: Self-reported height, weight and waist circumference, a physical activity index calculated from the product of self-reported physical activity intensity, duration and frequency, the Baecke physical activity questionnaire. Subsamples: Measured height, weight and waist circumference, measured body composition and insulin sensitivity, cardiorespiratory fitness, gene expression in adipose tissue. Results: Physical activity decreased the influence of genetic factors on BMI and waist circumference. The association between sports activity and obesity and of that between sports activity and cardiorespiratory fitness was largely due to genetic factors influencing both traits. Genetic factors contributed significantly to individual differences in physical activity, with genetic factors explaining between 41% and 64% of the variance in four physical activity indexes. Acquired obesity was associated with poor cardiorespiratory fitness and lowered transcript levels of genes involved in mitochondrial function in adipose tissue. Conclusions: The influence of genetic factors on obesity measures was smaller in physically active subjects as compared to inactive subjects indicating a geneenvironment association between physical activity and genes predisposing to obesity. This suggests that the individuals at greatest genetic risk for obesity would benefit most from physical activity. Genetic factors influence both would benefit most from physical activity. Genetic factors influence both physical activity and obesity traits and explain a major part of their relationships. Acquired obesity causes poor cardiorespiratory fitness, insulin resistance and downregulation of genes involved in mitochondrial function.
Source: Työväentutkimus Vuosikirja
Author: Linda Mustelin
Language: English
Subfield: Genetics
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W1568674623