Showing papers by "Claude Bouchard published in 1990"
TL;DR: Although body fat distribution is now considered as a more significant risk factor for CVD and related death rate than obesity per se, further research is clearly needed to identify the determinants of bodyfat distribution and the causal mechanisms involved in the metabolic alterations.
Abstract: Several epidemiological studies have reported that the regional distribution of body fat is a significant and independent risk factor for cardiovascular disease (CVD) and related mortality. Although these associations are well established, the causal mechanisms are not fully understood. Numerous studies have, however, shown that specific topographic features of adipose tissue are associated with metabolic complications that are considered as risk factors for CVD such as insulin resistance, hyperinsulinemia, glucose intolerance and type II diabetes mellitus, hypertension, and changes in the concentration of plasma lipids and lipoproteins. The present article summarizes the evidence on the metabolic correlates of body fat distribution. Potential mechanisms for the association between body fat distribution, metabolic complications, and CVD are reviewed, with an emphasis on plasma lipoprotein levels and plasma lipid transport. From the evidence available, it seems likely that subjects with visceral obesity represent the subgroup of obese individuals with the highest risk for CVD. Although body fat distribution is now considered as a more significant risk factor for CVD and related death rate than obesity per se, further research is clearly needed to identify the determinants of body fat distribution and the causal mechanisms involved in the metabolic alterations. It appears certain, however, that an altered plasma lipid transport is a significant component of the relation between body fat distribution and CVD.
1,309 citations
TL;DR: It is concluded that the most likely explanation for the intrapair similarity in the adaptation to long-term overfeeding and for the variations in weight gain and fat distribution among the pairs of twins is that genetic factors are involved.
Abstract: We undertook this study to determine whether there are differences in the responses of different persons to long-term overfeeding and to assess the possibility that genotypes are involved in such differences. After a two-week base-line period, 12 pairs of young adult male monozygotic twins were overfed by 4.2 MJ (1000 kcal) per day, 6 days a week, for a total of 84 days during a 100-day period. The total excess amount each man consumed was 353 MJ (84,000 kcal). During overfeeding, individual changes in body composition and topography of fat deposition varied considerably. The mean weight gain was 8.1 kg, but the range was 4.3 to 13.3 kg. The similarity within each pair in the response to overfeeding was significant (P less than 0.05) with respect to body weight, percentage of fat, fat mass, and estimated subcutaneous fat, with about three times more variance among pairs than within pairs (r approximately 0.5). After adjustment for the gains in fat mass, the within-pair similarity was particularly evident with respect to the changes in regional fat distribution and amount of abdominal visceral fat (P less than 0.01), with about six times as much variance among pairs as within pairs (r approximately 0.7). We conclude that the most likely explanation for the intrapair similarity in the adaptation to long-term overfeeding and for the variations in weight gain and fat distribution among the pairs of twins is that genetic factors are involved. These may govern the tendency to store energy as either fat or lean tissue and the various determinants of the resting expenditure of energy.
1,241 citations
01 Jan 1990
TL;DR: Part I: Consensus Statement and Introductory Addresses; Part II: Assessment and Determinants of Physical Activity, Fitness, and Health.
Abstract: Part I: Consensus Statement and Introductory Addresses. Part II: Assessment and Determinants of Physical Activity, Fitness, and Health. Part III: Human Adaptation to Physical Activity. Part IV: Physical Activity and Fitness in Disease. Part V: Physical Activity and Fitness in Growth, Reproductive Health, and Ageing. Part VI: The Risks of Exercising.
301 citations
TL;DR: In general, subjects practicing vigorous activities on a regular basis had lower subcutaneous skinfold thicknesses and waist-to-hip ratios (WHRs) than those not performing these activities.
256 citations
195 citations
TL;DR: In both studies, a higher dietary energy intake was associated with an earlier age at menarche, and body fat was not strongly related to the onset of menstruation.
Abstract: Age at menarche shows a downward secular trend and differs according to socioeconomic conditions, presumably the result of dietary variations. We report two studies conducted in Quebec City in which the relation between diet and menarche was evaluated. In 1978-1980, baseline information for these studies was obtained on girls aged 9 through 15 and included body weight, height, fatfold thickness at six sites, percent of body fat (derived from underwater weighing), and a 3-day dietary record. In a cross-sectional study of 207 girls aged 11 through 15, we compared dietary patterns between premenarcheal and menarcheal girls using logistic regression. In a 6-year follow-up study of 109 girls who had not experienced menarche at the baseline data collection, the relation between time of occurrence of menarche and dietary patterns was assessed using proportional hazards models. The results confirm the association between body weight and age at menarche. Body fat, however, was not strongly related to the onset of menstruation. In both studies, a higher dietary energy intake was associated with an earlier age at menarche. Dietary composition, and dietary fat in particular, was not related to menarche.
92 citations
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TL;DR: It is suggested that a greater EI in the form of fat influences total adiposity, as well as regional subcutaneous fat distribution, only when high fat consumers are compared to low fat consumers.
Abstract: The relationship between dietary fat intake, adiposity and regional subcutaneous fat distribution was studied in 344 men and 335 women (aged 35-55 years). Three-day food records were used to estimate total energy intake (EI) and percent intake of all macronutrients. Subjects were categorized as having an EI that was low (lower quantile) or high (upper quantile) in fat. Results showed that both men and women with a higher percent of EI in the form of fat weighed significantly (P less than 0.05) more, and had higher subcutaneous adiposity indices than subjects with a low fat intake. There was also a significant difference for both sexes between low and high fat intake groups in trunk and extremity skinfolds and trunk/extremity skinfolds ratio adjusted for the sum of skinfolds. However, this effect was not present when correlations between percent fat intake and body composition or regional fat distribution variables adjusted for total fat intake per unit of body mass were computed. These results suggest that a greater EI in the form of fat influences total adiposity, as well as regional subcutaneous fat distribution, only when high fat consumers are compared to low fat consumers.
87 citations
56 citations
TL;DR: The aim of the present study was to investigate the associations between total adiposity, body fat distribution, and plasma lipoprotein levels within groups of women defined on the basis of apolipoprotein E phenotypes, in order to verify whether apoE polymorphism could modify these associations.
TL;DR: This work proposes a design that involves submitting both members of several MZ twin pairs to an ethically acceptable experimental treatment capable of inducing an adaptative response, and finds that this design with MZ twins may be helpful in the study of human variation for multifactorial phenotypes.
Abstract: Despite some evidence that genotype-environment interaction (G x E) effects may be involved in the variation observed in behavioral and biological traits, few attempts have been made to detect and quantify this component of genetic variation in humans. We propose that one way to achieve this goal is to challenge several genotypes in a similar manner, submitting both members of several MZ twin pairs to an ethically acceptable experimental treatment capable of inducing an adaptative response. In this situation, the G x E effect can be assessed with a two-way analysis of variance for repeated measures on one factor, the treatment effect. In this design, twins are considered nested within the pair, whereas the treatment effect is considered a fixed variable. The intrapair resemblance in the response to the treatment is quantified with an intraclass correlation coefficient computed with between-sibhips and within-sibhips means of squares. To illustrate this approach, changes induced by long-term endurance training were studied in 10 MZ twin pairs. Significant intrapair resemblance in the response of maximal oxygen uptake was observed, with about 7 to 8 times more variance between pairs than within pairs. This design with MZ twins may be helpful in the study of human variation for multifactorial phenotypes.
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TL;DR: It is possible that there is a real major gene effect on SBP but that the genotype for elevated SBP has not yet expressed itself in the offspring as they have not yet gone through the risk period, and this possibility needs to be evaluated further in additional studies involving older offspring.
Abstract: Commingling and segregation of age-sex-adjusted systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean arterial blood pressure (MBP) were examined in 1,560 individuals from 374 French-Canadian nuclear families. After correction for skewness, evidence in favor of two commingled distributions was found for SBP in the combined data (parents and offspring) and in parents, but not in offspring. Segregation analysis (using the computer program POINTER) suggested that a multifactorial contribution to all three phenotypes was greater in offspring than in parents, which could be the result of either polygenic or shared environmental components relevant to sibships, or both. Statistical evidence was found for a major effect on SBP. However, Mendelian transmission of the major effect was rejected, and no transmission of the major effect (equal tau's) was not. This is just the opposite to what would be expected if the major effect was due to a major gene, and it would ordinarily be considered as sufficient evidence to refute a major gene effect on SBP. However, the commingling in parents but not in offspring (who are all below 26 years of age), and the finding of equal transmission probabilities (nearly equal to 1), are compatible with an alternative interpretation. It is possible that there is a real major gene effect on SBP but that the genotype for elevated SBP has not yet expressed itself in the offspring as they have not yet gone through the risk period. Accordingly, this possibility needs to be evaluated further in additional studies involving older offspring.
TL;DR: The results indicate that knee extensor muscles of sedentary Black and White males have similar anaerobic performance power and capacities, however, the results reveal that sedentaryBlack subjects experience a greater degree of fatigue than sedentary Whites during an an aerobic exercise lasting longer than 30 s.
Abstract: The anaerobic performance characteristics of 15 Black males of African ancestry (25 +/- 2 yr; mean +/- SD) and 17 White males of French Canadian ancestry (22 +/- 2 yr) were compared. All subjects were sedentary. Morphological characteristics and body composition were similar in both groups. They were tested for maximal force during voluntary isometric contraction of the knee extensors and for total work output during 10 s, 30 s, and 90 s of maximal and repetitive knee extensions. Results indicated no significant differences between Blacks and Whites in maximal force of the knee extensors (736 +/- 78 N vs 722 +/- 11 N, respectively) and in total work output during the 10-s (1134 +/- 246 J vs 1124 +/- 207 J) and 30-s (2735 +/- 519 J vs 2779 +/- 647 J) tests. There was a difference of about 400 J between Blacks and Whites in the total work output during the 90-s test, but this difference was not statistically significant. However, significant differences were found between Blacks and Whites in the peak power output decrement during the last 60 s of the 90-s anaerobic test. These differences in peak power output between the two groups ranged between 7 and 10 W during the last 30 s of the 90-s test. The results indicate that knee extensor muscles of sedentary Black and White males have similar anaerobic performance power and capacities. However, the results reveal that sedentary Black subjects experience a greater degree of fatigue than sedentary Whites during an anaerobic exercise lasting longer than 30 s.
TL;DR: Stepwise multiple regression analyses indicated that once the variance explained by plasma LPL activity and by the insulin area was considered, no other metabolic variable could account for the variation in VLDL-CHOL and VLDl-apo B levels, whereas fasting FFA levels explained a further 5% of the V LDL-TG variance.
Abstract: Potential correlates of plasma very-low-density lipoprotein (VLDL) concentration and composition were studied in a sample of 75 premenopausal women. Fasting plasma free fatty acid (FFA) levels, as well as plasma glucose and insulin levels in the fasting state and during an oral glucose tolerance test, displayed significant positive correlations with plasma triglyceride (TG) and VLDL-TG levels ( P P P P
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