To assess perceptions of fitness, intensity and frequency of habitual physical activity as predictors of cardiovascular function, metabolic health and obesity.Cross-sectional correlational, with covariance adjustment of data for age and socio-economic status.An urban community of some 250,000 people.Convenience sample of healthy but relatively sedentary subjects, 172 males and 178 females aged 14-68 years.Self-reports of perceived fitness, habitual activity, intensity and frequency of exercise; standard laboratory tests of cardiovascular function (resting heart rate, PWC 150/kg, systolic and diastolic blood pressure), metabolic health (blood glucose, total cholesterol, HDL-cholesterol, triglycerides and uric acid), obesity (body mass index, skinfolds, hydrostatic body fat, and abdominal circumferences) and socio-economic status (education, job classification and income).In men, the strongest associations of fitness markers were with peer comparisons of fitness and activity. In women, such comparisons also yielded significant positive associations, but the most consistent relationships of fitness were with Godin questionnaire ratings of sweat-inducing and frequent heavy activity. Perceptions of intense activity were associated more with cardiovascular than with metabolic health. Perceptions of frequent activity (peer activity ratings, occupational walking, and the number of activities reported) were associated with control of body fat, and to a lesser extent with cardiovascular function, but were unrelated to markers of metabolic health.Perceptions of personal fitness, intensity and frequency of habitual activity are all associated with markers of health-related fitness after allowance for effects of gender, age and socio-economic status. The public should thus be encouraged to pursue activity that they perceive as frequent, intense and improving their fitness.
Six skinfold measurements for male and female athletes (N=456) at the 1976 Montreal Olympic Games were analyzed to identify principal components of fatness and anatomical distribution of fat, i.e., fat patterning. As in non-athletes, two principal components were evident among the athletes. All skinfolds were correlated positively with the first component, which was termed fatness, while extremity fat measurements were correlated positively and trunk measurements were correlated negatively with the second principal component, which was termed an extremity/trunk ratio component. The two principal components accounted for about 85% of the variance. The first component was related to control variables in order of descending contribution to its variance as follows: sex (21–31%), sport (19%), ethnicity (3%), and age (1–3%). Likewise, the second component (extremity/trunk ratio) was related to the control variables: sex (20–35%), age (4–7%), ethnicity (2%), and sport (2%). Fatness is more influenced by sport and by inference training than is the anatomical distribution or patterning of fat on the extremities relative to the trunk. The latter characteristic may be more dependent on biological or environmental factors unrelated to sport and training.
No abstract is provided for this article.
No abstract is provided for this article.
Studies of monozygotic twins in the context of overfeeding and energy deficit experiments have shown that gene–environment interactions affect energy balance. From a clinical standpoint, this implies that some individuals are more susceptible to body-weight gain or loss than others because of genetic differences. This opens new perspectives in predictive medicine. In the future, health professionals should be able to count on early diagnosis of individuals at risk for developing long-term metabolic problems and obesity or for not responding adequately to clinical interventions. However, before predictive medicine is in a position to contribute significantly to prevention or treatment of patients, an enormous amount of work has to be done to identify all genetic and environmental factors of relevance, and their network of interactions.
No abstract is provided for this article.
This brief review constitutes a synthesis of some of the research conducted in our laboratory about the role of inheritance in human variation observed for subcutaneous fat, total fat mass and subcutaneous fat distribution. Our first studies were of the genetic epidemiology type and were conducted on a cohort of 1,698 subjects from 409 families of French descent living in the greater Québec city area. These studies have shown that heritability of the amount of subcutaneous fat was almost zero, while the additive genetic effect reached about 25% of human variation, after statistical control over the effects of age and gender, for total fat mass and regional subcutaneous fat distribution. On the other hand, there are considerable individual differences in the response to overfeeding and those that pertain to body weight and body composition, and the various components of daily energy expenditure in subjects kept inactive, are mainly determined by the genotype. These findings come from a study on the response to chronic overfeeding, sustained for 22 consecutive days, undertaken with 6 pairs of identical twins. In general, our research shows that there are individuals who are more at risk of becoming obese because of undetermined genetic characteristics but that are apparently associated somehow with the various components of habitual energy expenditure.
A growing body of evidence indicates that genotype-by-physical activity interactions on various health-related outcomes do exist. Observational studies have shown that relationships between DNA sequence variants and risk factors are significantly different between sedentary and physically active individuals, while exercise intervention studies have demonstrated that genetic variation contributes significantly to interindividual variation in responsiveness to exercise training. The knowledge base on gene–activity interactions will grow considerably within a few years when large observational genome-wide association study (GWAS) consortia will report their findings. Progress with exercise intervention studies will be slower because of resource requirements. However, such studies are desperately needed to fully understand the genetics as well as the exercise biology of complex traits and to confirm the gene–exercise interactions derived from observational studies. Furthermore, development of personalized exercise medicine applications will be difficult or even impossible without a proper understanding of gene–exercise interactions.
A large body of evidence suggests that the environment plays an important role in the development of obesity. The hormone-sensitive lipase (encoded by the LIPE gene) is an intracellular enzyme that mobilises fat stores in a hormone-stimulated manner. The aim of the present study was to determine the effects of the LIPE C-60G polymorphism on body fat and plasma lipid and lipoprotein concentrations, and to test for its interaction with physical activity. The LIPE C-60G polymorphism was genotyped in 862 subjects from the Quebec Family Study. Body mass index (BMI), fat mass, percentage body fat, abdominal fat areas assessed by computed tomography, and detailed fasting plasma lipid and lipoprotein profiles were measured. Levels of physical activity were estimated using a three-day diary, and a moderate to strenuous physical activity score was retained for this study. The main effects of the LIPE C-60G polymorphism, physical activity and their interaction were determined by regression analyses separately in men and women using the MIXED model procedure. In men, we observed significant gene-physical activity interactions for BMI (p = 0.006), fat mass (p = 0.04), abdominal visceral fat area (p = 0.005) and plasma cholesterol (C) high-density lipoprotein cholesterol (HDL-C) ratio (p = 0.003). A high level of physical activity was associated with reduced adiposity and a lower plasma-C/HDL-C ratio, but only in non-carriers of the genetic variant (G-60 allele). In women, no evidence of a gene by physical activity interaction was observed, except for subcutaneous abdominal fat (p = 0.05). These results suggest that the associations between physical activity and body fat and plasma lipoprotein/lipid concentrations in men are dependent on the LIPE C-60G polymorphism, and highlight the importance of taking into account the role of gene-physical activity interactions in candidate gene studies of obesity and obesity-related traits.
