C Leblanc

Laval University, Québec, Quebec, Canada

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Publications (57)174.52 Total impact

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    ABSTRACT: The objective of this study was to compare changes in body composition and the metabolic profile between women taking an intermittent diet (ID) and women taking a continuous diet (CD). Twenty-five obese postmenopausal women were randomized to an ID (n = 13) or a CD (n = 12). In the ID, 5-week energy restriction periods were followed by 5-week weight stabilization periods. In the CD, 15 weeks of energy restriction was followed by 5 weeks of weight stabilization. Outcome measures before, during, and after weight loss, as well as after a 1-year follow-up, were body weight and composition, waist circumference, resting metabolic rate, and fasting lipid and glucose levels. Body weight, waist circumference, percentage fat mass, and fat mass decreased significantly and similarly in both groups (P < 0.0001). Both groups showed similar overall decreases in plasma total cholesterol and triglycerides (all P < 0.05). Low-density lipoprotein cholesterol improved significantly in the CD group only, whereas fasting glucose decreased significantly in the ID group only. High-density lipoprotein cholesterol and resting metabolic rate remained stable in both groups. Fasting plasma triglyceride and glucose levels were the only metabolic variables to further improve after the fifth week of the protocol. At the 1-year follow-up, both interventions were associated with successful and similar weight loss maintenance and improvements in fasting plasma glucose levels. The ID resulted in similar short- and long-term changes in body composition and metabolic profile compared with a CD. Most improvements occurred during the first 5 weeks of treatment in both interventions.
    Menopause (New York, N.Y.) 06/2012; 19(8):870-6. · 3.08 Impact Factor
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    ABSTRACT: Family resemblance in fatness has been studied in 481 individuals from 114 families of French descent living in the greater Quebec city area. Subjects were measured for the following fatness indicators: triceps, biceps, subscapular, suprailiac, abdominal and medial calf skinfolds. The sum of these six skinfolds as well as a prediction of percent body fat (Durnin and Rahaman 1967) were also considered. Data were standardized for appropriate age and sex classes yielding SS scores. The influence of relevant lifestyle variables (energy intake, energy expenditure and socioeconomic status) were statistically removed from SS yeilding residual scores (RS) that were then submitted to familial analyses. Analyses of variance indicate that there is a larger between family variation than within (P less than or equal to 0.01) for SS when considering either the whole nuclear family or sibships; in these instances, the intra-class correlation ranges from 0.15 to 0.26. There was, however, no significant resemblance among spouses for the SS fatness indicators. Similar values were essentially found for RS fatness indicators. Furthermore, husband-wife inter-class correlations were not significant with the exception of subscapular and calf skinfold RS. Covariations between biological relatives are however significant (0.16 less than or equal to r less than or equal to 0.24, P less than or equal to 0.01) for SS and remain essentially unchanged after statistical control over the lifestyle variables (0.16 less than or equal to r less than or equal to 0.40, P less than or equal to 0.01). The findings that spouses do not covary significantly in fatness, while biological relatives of traditional nuclear families exhibit a significant degree of resemblance even after statistical control over daily energy intake, daily energy expenditure and socioeconomic status provide evidence supporting the hypothesis that there is a substantial genetic effect in human fatness.
    Annals of Human Biology 07/2009; 10(2):111-8. · 1.48 Impact Factor
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    ABSTRACT: The technique of path analysis was used to assess inherited and environmental variance components in physical fitness indicators measured in 1630 subjects from 375 families of French descent living in the greater Québec city area. For that purpose, submaximal power output (PWC150/kg), muscular endurance, muscular strength, reaction time and movement time were evaluated during a visit of the family to the laboratory. Inter-class correlations in various types of relatives were computed from scores adjusted for linear and non-linear effects of age and sex by a regression procedure (Y = age + sex + (age X sex) + age2). Correlations were then used in the path analytic BETA model which allows the partition of transmissible variance (t2) into genetic (h2) and cultural (b2) components. Results indicated that t2 accounted for 18% (movement time) to 63% (muscular strength) of the phenotypic variance. The contribution of genetic factors was found to be negligible for PWC150/kg and movement time, and accounted for about 20% of the phenotypic variance for reaction time and muscular endurance and 30% for muscular strength, while non-transmissible variance (1 - t2) accounted for 37% (muscular strength) to 82% (movement time) of the phenotypic variance. These results suggest that biological variation observed in the physical fitness level of a healthy population is mainly associated with non-transmissible environment factors and that the contribution of heredity is moderate and clearly lower than previously reported.
    Annals of Human Biology 07/2009; 14(5):425-34. · 1.48 Impact Factor
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    ABSTRACT: The aim of this study was to determine the independent contribution of previously reported risk factors for adult overweight and obesity. A cross-sectional (n=537) and a longitudinal (n=283; 6-year follow-up period) analysis was performed for nine risk factors for overweight and obesity assessed in adult participants (aged 18-64 years) of the Quebec Family Study (QFS). The main outcome measure was overweight/obesity, defined as a BMI>or=25 kg/m2. Using logistic regression analysis adjusted for age, sex, and socioeconomic status, short sleep duration, high disinhibition eating behavior, low dietary calcium intake, high susceptibility to hunger behavior, nonparticipation in high-intensity physical exercise, high dietary restraint behavior, nonconsumption of multivitamin and dietary supplements, high dietary lipid intake, and high alcohol intake were all significantly associated with overweight and obesity in the cross-sectional sample. The analysis of covariance adjusted for age, socioeconomic status, and all other risk factors revealed that only individuals characterized by short sleep duration, high disinhibition eating behavior, and low dietary calcium intake had significantly higher BMI compared to the reference category in both sexes. Over the 6-year follow-up period, short-duration sleepers, low calcium consumers, and those with a high disinhibition and restraint eating behavior score were significantly more likely to gain weight and develop obesity. These results show that excess body weight or weight gain results from a number of obesogenic behaviors that have received considerable attention over the past decade. They also indicate that the four factors, which have the best predictive potential of variations in BMI, be it in a cross-sectional or a longitudinal analytical design, do not have a "caloric value" per se.
    Obesity 05/2009; 17(10):1964-70. · 3.92 Impact Factor
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    ABSTRACT: Topiramate (TPM) has been reported to reduce body weight beyond a placebo in the treatment of obese participants, but the effect of this agent on components of energy balance has not yet been established in humans. Thus, the aim of this study was to study the impact of TPM on food preferences, measures of satiety, food intake, resting metabolic rate (RMR), and 24-h energy expenditure. The study design consisted of a 6-month, single-center, randomized, double-blind, parallel group, placebo-controlled trial with a 6-month open-label extension. The study included 68 sedentary men with abdominal obesity (waist circumference > or = 100 cm), of between 25 and 55 years of age, with a dyslipidemic profile and a body mass index (BMI) > or = 27 and < or = 40 kg/m(2). Treatment with TPM produced significant changes in anthropometric variables and body composition compared with placebo. However, at the end of the 1-year study, the placebo/TPM group showed similar weight loss and reduction in body fatness compared with the TPM/TPM group. For instance, at the end of the 12-month intervention, mean percentage of body weight loss from baseline was about -5% in both groups (-4 kg fat loss). Topiramate treatment reduced energy intake, be it in the context of an ad libitum buffet-type meal or under free living conditions. The 24-h daily energy expenditure (DEE) assessed by whole-body indirect calorimetry adjusted for body weight and age was not altered by TPM treatment. Topiramate treatment produced significantly greater weight loss than placebo and the majority of this loss was explained by a decrease in body fat stores. Most of the weight loss effect produced by TPM therapy was observed within a period of 6 months. Finally, TPM treatment had an impact on energy balance through a reduction in food intake that appears to have created an energy deficit of about 30,000-40,000 kcal compared with treatment with the placebo over 6 months.
    European Journal of Clinical Pharmacology 03/2007; 63(2):123-34. · 2.74 Impact Factor
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    ABSTRACT: Activity level and energy intake were estimated from 3-day records, including a weekend day, in parents and children from families of French descent. Subcutaneous fat from the summation of six skinfolds, fasting serum triglycerides, total and high-density lipoprotein cholesterol, and submaximal power output (PWC150) derived from a cycle ergometer test also were determined in these subjects. Dependent variables were normalized through log10 or squre-root transformation, and scores were adjusted by generation for the effects of age and gender. Correlations with residual scores were performed with pairs of natural parents and child (N ≧ 1057) and pairs of foster parent and adopted child (N ≧ 283). Coefficients were generally little affected by statistical control over current activity level and energy intake. Pairs of biological relatives were classified as either very similar (25% of pairs) or very dissimilar (25% of pairs) in terms of energy intake or activity level. Correlations revealed that similarity or discordance in energy intake or activity level had only a slight effect on parent-child resemblance. In addition, duration of cohabitation had little influence on parent-child covariation. It was concluded that parent-child resemblance in subcutaneous fat, work capacity, and blood lipids are not significantly affected by current patterns of energy intake, activity level, or duration of cohabitation.
    American Journal of Human Biology 05/2005; 1(2):209 - 215. · 2.34 Impact Factor
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    ABSTRACT: Dietary patterns play an important role in the control of body weight. The aim of this study was to verify whether changes in some dietary patterns over a 6-y follow-up period would be associated with weight changes. A sample of 248 volunteers of the Québec Family Study were measured twice (visit 1: 1989-1994; visit 2: 1995-2000). Body weight, percentage body fat, subcutaneous skinfold thicknesses, and waist circumference measurements as well as 3-d dietary and physical activity records were obtained at each visit. At visit 2, all participants filled out a food-based questionnaire examining changes in the consumption of 10 food categories. To further investigate the relation between changes in food-group consumption and body-weight changes, a total of 51 food subcategories were identified from dietary records. A self-reported decrease in the consumption of food in the fat group or an increase in consumption in the fruit group from the food-based questionnaire predicted a lower increase in body weight and adiposity indicators over time. A more detailed examination of the change in food groups between diet records revealed that increases in the consumption of whole fruit as well as skimmed milk and partly skimmed milk were the 2 food patterns that negatively correlated with the changes of each body weight-related indicator. These results show that changes in the consumption of some specific food groups are associated with body-weight changes. Such specific eating patterns could help to improve obesity treatment and prevention.
    American Journal of Clinical Nutrition 08/2004; 80(1):29-37. · 6.50 Impact Factor
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    ABSTRACT: Subjects with occupational asthma (OA) often report nasal symptoms, but nasal reactions to inhalation challenges with occupational agents have not been well characterized. Fifteen subjects with OA (eight due to high-molecular-weight agents--flour and guar gum--and seven due to isocyanates) underwent inhalational challenges using closed-circuit devices (dry particles for high-molecular-weight agents and gas generator for isocyanates) on two occasions, 2-4 weeks apart in a random fashion. On one occasion, they inhaled through the nose and, on another, through the mouth. The FEV1 was monitored for up to 8 h afterward, and symptoms were documented with a standardized questionnaire on nasal symptomatology, assessment of nasal resistance by rhinomanometry, and nasal lavage for the examination of cells and mediators. Inhaling through the mouth and through the nose: 1) yielded similar asthmatic responses (25+/-8% and 22+/-10% maximum changes in FEV1) 2) more than doubled the peak nasal symptoms and nasal resistance when the maximum daily response was compared with prechallenge results. This increase occurred on the days of inhalational challenges through the mouth and through the nose. There were some significant responses assessed by nasal lavage in terms of cells and mediators, again with no differences between the days of challenges through the mouth and through the nose. Inhaling occupational agents of high or low molecular weight, including isocyanates, whether through the mouth or nose: 1) results in a similar asthmatic response 2) causes a significant nasal response in terms of symptoms and an increase in nasal resistance 3) causes some significant changes in inflammatory cells and mediators.
    Allergy 10/1998; 53(9):840-8. · 5.88 Impact Factor
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    ABSTRACT: Occupational asthma (OA) is a useful model for the study of asthma in humans. The possibility that inhaled corticosteroids, in addition to withdrawal from the workplace, could improve clinical and functional recovery from OA can be hypothesized. We assessed clinical, functional, and behavioral characteristics of 32 subjects (22 male, 10 female), in all but one of whom OA was confirmed by specific inhalation challenges induced by either high- (n=13) or low-molecular-weight (n=19) agents within 3 mo after cessation of exposure. In this randomized, crossover, double-blind study, subjects (paired for baseline PC20 and duration of symptoms after exposure) received either placebo or 1,000 micrograms of inhaled beclomethasone daily for 1 yr, followed by the alternate medication for 6 mo. Various clinical, functional, and behavioral parameters were examined at each 3-mo visit. Significant improvement in clinical (nocturnal symptoms, cough), functional (morning and evening peak expiratory flow rates), and behavioral (quality of life) parameters were detected in the active-treatment period, although the magnitude of the improvement was relatively small. Side effects (oropharyngeal, reduced cortisol) were similar in the placebo and treatment groups. Distinguishing subjects who started with the active preparation from those who were given placebo first showed that most clinical and behavioral parameters improved in the former instance, whereas there was no significant difference in the latter. We conclude that inhaled corticosteroids induce a small but significant overall improvement of the asthmatic condition in subjects with occupational asthma caused by high- and low-molecular-weight agents after withdrawal from exposure. The beneficial effect is, however, more pronounced if inhaled steroids are given early after diagnosis.
    American Journal of Respiratory and Critical Care Medicine 04/1996; 153(3):953-60. · 11.04 Impact Factor
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    ABSTRACT: High doses of inhaled corticosteroids (ICS) (budesonide and beclo-methasone > or = 800 micrograms.day-1) are commonly used in the treatment of asthma. Some investigators have presented evidence for cutaneous effects (bruising), which suggests systemic absorption. This study aimed to assess the prevalence of skin bruising, relate the occurrence of skin bruising to adrenocortical function, and determine the risk factors for skin bruising. One hundred adult asthmatic subjects taking high doses (800-2,000 micrograms.day-1) of ICS for 3 months or more were recruited in an asthma clinic, and 100 control subjects paired for sex and age were recruited from an ophthalmology out-patient clinic. A detailed questionnaire on asthma, general habits and cutaneous lesions was administered. A cutaneous examination was performed. Urine cortisol levels were assessed on two consecutive days. Blood cortisol level and the response to Cortrosyn injection (60 min test) were evaluated. One hundred adult asthmatics (66 females and 34 males), 73 on beclomethasone and 27 on budesonide, were included. The prevalence of skin bruising was 71% based on the questionnaire (32% in controls) and 48% (39 out of 81 subjects) based on direct examination of the skin. We found a satisfactory association between the response to questionnaire and examination of the skin. Adrenocortical function testing showed that a minority of subjects (14 with at least one abnormal test) had lower urinary or blood cortisol levels. These low cortisol levels occurred in subjects who reported skin bruising. By multiple logistic regression, being a female (odds ratio (OR) = 20; 95% confidence interval (95% CI) = 13-33) and taking ICS for asthma (OR = 12; 95% CI = 8-18) were significantly (t = 5.4) related to the likelihood of developing skin bruising. In addition, among the asthmatic subjects, being older (OR = 1.6; 95% CI = 1.1-2.4/10 yrs interval) (t = 2.3) and being a female (OR = 22; 95% CI = 7-75) (t = 5.0) influenced the occurrence of skin bruising as documented by questionnaire. In asthmatic subjects, taking high doses of ICS is associated with: 1) increased occurrence of skin bruising by comparison with controls, particularly in older subjects; and 2) a generally normal adrenocortical function, although this function is significantly lower in subjects reporting skin bruising.
    European Respiratory Journal 02/1996; 9(2):226-31. · 6.36 Impact Factor
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    ABSTRACT: In order to determine 1) the features of airway inflammation after removal from exposure to high (HMW) and low (LMW) molecular weight agents 2) if there are any differences in the pattern of inflammation induced by these two types of agents, we studied 18 subjects with a recently confirmed diagnosis of occupational asthma (OA) due to HMW (n = 11) and LMW (n = 7) agents. The duration of asthma symptoms varied from 2 to 108 months (mean 33 months), and withdrawal from exposure to the sensitizing agent from 3 to 24 weeks (mean 10 weeks). All subjects underwent measurements of expiratory flow rates, methacholine inhalation tests, and a flexible bronchoscopy with bronchoalveolar lavage (BAL) and bronchial biopsies. Endoscopic findings were compared with a group of 10 normal subjects. At the time of the bronchoscopy, asthma symptoms were minimal in most subjects. Although 15/18 subjects had normal forced expiratory volume in one second (FEV1 > 80% pred), all subjects had increased airway responsiveness to methacholine (provocation concentration producing a 20% fall in FEV1 = 0.2-10.0 mg.ml-1). BAL analysis showed similar median percentages of the total number of cells and differentials in control subjects and those exposed to HMW and LMW agents. Bronchial biopsies showed that mean inflammatory cell count, both epithelial and sub-epithelial, was similarly raised in OA subjects exposed to either HMW or LMW agents, compared to controls, except for epithelial lymphocyte count. In contrast to the controls, bronchial biopsy of both groups with OA also showed other changes such as extensive epithelial desquamation, ciliary abnormalities of the epithelial cells, smooth muscle hyperplasia and subepithelial fibrosis.(ABSTRACT TRUNCATED AT 250 WORDS)
    European Respiratory Journal 09/1994; 7(9):1567-75. · 6.36 Impact Factor
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    ABSTRACT: The aims of the study conducted on lawn cutters were: (1) to evaluate exposure to pollens and molds; and (2) to assess the prevalence rate of IgE sensitization and symptoms in relation to exposure to pollens and molds. Environmental assessment was done with the use of personal samplers on eight workers. Our population consisted of 181 municipal park workers, including 128 lawn cutters and 67 control subjects (blue-collar workers in the hospital). A questionnaire was administered, as well as skin prick tests with seven common inhalants including pollens and eight grass molds. The main outcome variables were grass or mold sensitization (at least one of eight molds) and work-related rhinitis, conjunctivitis, and rhinoconjunctivitis. Atopy and exposure to park-related allergens, as well as sensitization to grass pollens, were considered as explanatory factors. Smoking was taken into consideration as a covariant. Both presence and duration of occupational exposure to park-related allergens were considered as parameters of exposure. Duration of exposure (months x years of exposure as lawn cutters) was used as a continuous or as a categorical variable. Environmental monitoring showed that the concentration of pollens and molds decreased in magnitude from samples collected close to lawn cutters faces, short distance away in parks, and in the general environment. There was no difference in the prevalence rates for atopy between lawn cutters (32%) and control subjects (37%). Sensitization rates to grass pollen were also similar in lawn cutters (18%) and in control subjects (22%). However, there was a tendency for prevalence rates of sensitization to molds to be greater among lawn cutters (12% to Alternaria) compared with control subjects (5%). In the logistic model atopy was significantly related to grass sensitization (odds ratio [OR] = 7.2), mold sensitization (OR = 9.3), and sensitization to Alternaria (OR = 5.8). Grass sensitization was a significant risk factor for park-related rhinitis (OR = 5.8), conjunctivitis (OR = 5.0), and rhinoconjunctivitis (OR = 9.4). Exposure for 12 years or more was associated with rhinoconjunctivitis with an OR of 4.1 (95% confidence interval, 1.0-16.7). Smoking was not significantly related to any outcome. We conclude that among lawn cutters exposure to pollens and molds is higher than in the general population, atopy is the main determinant of sensitization to these aeroallergens, and sensitization and, to a much lesser extent, exposure to grass are determinants of symptoms.
    Journal of Allergy and Clinical Immunology 03/1994; 93(2):437-45. · 12.05 Impact Factor
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    ABSTRACT: The objective of the study was to determine whether exposure to domestic animals plays a significant role, beyond atopy, in the development of immediate sensitization to animal-derived antigens. To test this hypothesis, 200 subjects with asthma (85 male subjects and 115 female subjects; mean age, 37 +/- 16 years) seen consecutively in an asthma clinic were enrolled in a cross-sectional survey. Each subject answered a questionnaire about allergy symptoms and past and current exposure to domestic animals. Skin prick testing with extracts of common inhalant allergens including antigens from eight species of animal (cat, dog, horse, rabbit, rat, mouse, guinea pig, and hamster) were also carried out. Seventy-nine percent of subjects were atopic, and 91% had kept animals at home at some point (figures were 80% for dogs, 68% for cats, 23% for rabbits, and 20% for rodents). Using two-by-two tables, we showed that skin reactivity to at least one animal antigen was strongly linked to atopy (86% of atopic subjects had skin reactions as compared with 34% of nonatopic subjects: p < 0.001) but not to previous and current exposure to domestic animals (78% of both exposed and never exposed subjects). However, with the use of logistic regression, the determinants of skin reactivity to animals were atopy (p < 0.001), followed by cumulative duration of exposure to domestic animals (p < 0.01). The number of animals times the number of species times the duration of exposure was also a significant determinant of skin reactivity (p = 0.05). We conclude that beyond the predominant role of atopy, cumulative duration of exposure to domestic animals is a significant determinant for immediate sensitization to animal-derived antigens in subjects with asthma.
    Journal of Allergy and Clinical Immunology 06/1993; 91(5):979-86. · 12.05 Impact Factor
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    ABSTRACT: One hundred thirty-four women, aged 36 +/- 4 (mean +/- SD) y, BMI 20 +/- 3 kg/m2, perceiving themselves as having either a low or high energy intake (EI), participated in a study to determine variations in EI. Information on EI and activity level was obtained from repeated 7-d records. The 40 subjects with the lowest EI (in kcal/kg body wt) were categorized as small eaters (SEs); the 40 subjects with the highest EI were considered to be large eaters (LEs). The absolute (in kcal) and relative (in kcal/kg body wt) EIs of the SE and LE groups were 1488 +/- 312 and 27 +/- 4 for the SE group, respectively and 2393 +/- 509 and 47 +/- 6 for the LE group, respectively. There was no significant difference in activity level or fat-free mass (FFM) between the groups. However, LEs weighed significantly less (51 vs 55 kg) and were leaner (22% body fat vs 33%) than were SEs. Individuals with similar FFM and activity level can vary significantly in EI needs.
    American Journal of Clinical Nutrition 03/1991; 53(2):425-9. · 6.50 Impact Factor
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    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.
    International Journal of Obesity 01/1991; 14(12):1085-94. · 5.22 Impact Factor
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    ABSTRACT: To evaluate the effect of intensity of physical activity on body fatness and fat distribution, observations of 1366 women and 1257 men who participated in the 1981 Canada Fitness Survey were analyzed. Subjects were tested for energy expenditure of leisure-time activities and estimated maximal oxygen uptake (VO2max), body fatness was measured by subcutaneous skinfold thicknesses, and anthropometric measurements were made. Subjects of both sexes were categorized into four subgroups on the basis of their participation in leisure-time activities of various intensities. 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. These differences remained statistically significant after a covariance analysis was used to remove the effect of total energy expenditure of leisure-time activities on subcutaneous fat and fat distribution. Moreover, the WHR remained significantly lower in subjects performing high-intensity exercise after the effect of subcutaneous fat on fat distribution was adjusted for.
    American Journal of Clinical Nutrition 03/1990; 51(2):153-7. · 6.50 Impact Factor
  • C Bouchard, L Pérusse, C Leblanc
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    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.
    Acta geneticae medicae et gemellologiae 02/1990; 39(1):85-9.
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    ABSTRACT: A group of 206 subjects (30-55 years) were studied with the objective of quantifying the relationships between fitness indicators (relative body weight (BMI), aerobic power, muscular endurance), health indicators and risk factors, (appraised age, cost of health services consumed, blood pressure (SBP and DBP), blood lipids (CHO and HDL), cigarette smoking). BMI was significantly correlated with the risk indicators in the male sample (.302 less than or equal to r less than or equal to .364) and in the female sample (.217 less than or equal to r less than or equal to .521). All coefficients were in the direction of the established biological assumption as concerns hazards to health. The discriminant analysis revealed that in the total group of men, 77% (p less than or equal to .001) of the subjects could be classified either in high or low BMI (greater than Q75 or less than or equal to Q25) on the basis of the scores in SBP, HDL, HDL/CHO. In the subgroup of women greater than or equal to 40 years, statistically significant classification occurred in 100% of the cases (p less than or equal to .001) on the basis of DBP, CHO, HDL/CHO, NCIG. The results indicate that BMI is a fitness determinant which is valid, convenient and easy to use in the detection of unfavorable health indices and when clinical intervention is justified.
    The Journal of sports medicine and physical fitness 10/1989; 29(3):253-61. · 0.73 Impact Factor
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    ABSTRACT: In order to quantify genetic and environmental determinants of physical activity level, 1,610 subjects from 375 families who lived in the greater Québec city area completed a three-day activity record in 1978-1981. Level of habitual physical activity, which includes all the usual activities of life, and exercise participation, which includes activities requiring at least five times the resting oxygen consumption and more, were derived from this record. Familial correlations were computed in several pairs of biologic relatives and relatives by adoption after adjustment for the effects of age, sex, physical fitness, body mass index, and socioeconomic status, and analyzed with a model of path analysis that allows the separation of the transmissible effect between generations (t2) into genetic (h2) and cultural (b2) components of inheritance. The transmission was found to be statistically significant, but was accounted for by genetic factors for level of habitual physical activity (t2 = h2 = 29%), and by cultural factors for exercise participation (t2 = b2 = 12%). Although non-transmissible environmental factors remain the major determinants of these two physical activity indicators in this population, the results suggest that children can acquire from their parents certain customs regarding exercise behavior and that the propensity toward being spontaneously active could be partly influenced by the genotype.
    American Journal of Epidemiology 06/1989; 129(5):1012-22. · 4.78 Impact Factor
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    ABSTRACT: Two studies dealing with the contribution of the genotype in individual differences for resting metabolic rate (RMR), thermic effect of a 4.2 MJ carbohydrate meal (TEM), and energy cost of submaximal exercise are reported. The genetic effect for RMR and TEM was studied in 31 pairs of parent-child, 21 pairs of dizygotic (DZ) twins, and 37 pairs of monozygotic (MZ) twins, whereas the heritability of the energy cost of submaximal exercise was determined from data on 22 pairs of DZ twins and 31 pairs of MZ twins. The heritability of RMR reached approximately 40% of the variance remaining after adjustment for age, gender, and fat-free mass, (FFM). The genetic effect for TEM was equivalent to at least 40% to 50% of the variation in the energy expended during four hours after the meal test. A highly significant genetic effect was found for fasting plasma glucose (greater than .72), but the results for fasting plasma insulin are unclear. No significant genetic variance was seen for the glucose and insulin response to the carbohydrate meal. Finally, heritability for the metabolic rate during cycle exercise was high (greater than or equal to .46) at low power output, but it became nonsignificant when the energy cost reached about 6 times the RMR.
    Metabolism 05/1989; 38(4):364-70. · 3.10 Impact Factor

Publication Stats

2k Citations
174.52 Total Impact Points

Institutions

  • 1979–2009
    • Laval University
      • Department of Social and Preventive Medicine
      Québec, Quebec, Canada
  • 1998
    • Centre hospitalier de l'Université de Montréal (CHUM)
      Montréal, Quebec, Canada
  • 1993–1998
    • Hôpital du Sacré-Coeur de Montréal
      • Center for Advanced Research in Sleep Medicine
      Montréal, Quebec, Canada
  • 1978
    • Université du Québec
      Québec, Quebec, Canada