Publications (59)257.21 Total impact
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Article: Genetic and environmental sources of variation in physical fitness.
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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. · 1.98 Impact Factor -
Article: Linkage of the Na,K-ATPase alpha 2 and beta 1 genes with resting and exercise heart rate and blood pressure: cross-sectional and longitudinal observations from the Quebec Family Study.
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ABSTRACT: To investigate whether genetic variations in the genes encoding the alpha and beta subunits of the Na,K-ATPase are linked with hemodynamic phenotypes. Cross-sectional data based on 533 subjects (no antihypertensive medication) were obtained from 150 families of phase 2 of the Quebec Family Study, together with longitudinal data from 338 subjects (105 families) who had been measured 12 years earlier in phase 1 of the Quebec Family Study. Restriction fragment length polymorphisms were examined at the alpha 2 (exon 1 and exon 21-22 with BglII) and beta 1 (Msp I and Pvu II) loci of Na,K-ATPase. Hemodynamic phenotypes measured included systolic and diastolic blood pressure, heart rate and rate-pressure product at rest and during low-intensity exercise. Sib-pair analysis revealed relatively strong linkages (P = 0.0003-0.002) between the resting heart rate and rate-pressure product and the alpha 2 exon 21-22 marker and alpha 2 haplotype. Moreover, the alpha 2 exon 21-22 marker showed suggestive linkages (P = 0.01 to 0.043) with resting systolic blood pressure and exercise diastolic blood pressure, heart rate and rate-pressure product, and the alpha 2 haplotype with exercise diastolic blood pressure and rate-pressure product and the 12-year change in resting systolic blood pressure (P = 0.03 to 0.05). Both the beta 1 Msp I marker and the beta 1 haplotype were linked with the resting rate-pressure product (P = 0.007 and 0.003, respectively), and all beta 1 markers showed linkage with the change in resting systolic blood pressure (P = 0.00005 to 0.024). In men, there was a significant (P = 0.01) interaction between the alpha 2 exon 21-22 genotype and the postglucose plasma insulin level with regard to resting systolic blood pressure. These data suggest that the alpha 2 and beta 1 genes of Na,K-ATPase contribute to the regulation of hemodynamic phenotypes in healthy subjects.Journal of Hypertension 04/1999; 17(3):339-49. · 4.02 Impact Factor -
Article: Golf injuries. An overview.
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ABSTRACT: Over the years, golf has become an increasingly popular sport, attracting new players of almost all ages and socioeconomic groups. Golf is practised by up to 10 to 20% of the overall adult population in many countries. Beyond the enjoyment of the sport itself, the health-related benefits of the exercise involved in walking up to 10 km and of relaxing in a pleasant natural environment are often reported to be the main motives for adhering to this activity by recreational golfers. Golf is considered to be a moderate risk activity for sports injury; however, excessive time spent golfing and technical deficiencies lead to overuse injuries. These are the 2 main causes of injuries among golfers, and each has specific differences in the pattern in which they occur in professional and amateur golfers. Golf injuries originate either from overuse or from a traumatic origin and primarily affect the elbow, wrist, shoulder and the dorsolumbar sites. Professional and weekend golfers, although showing a similar overall anatomical distribution of injuries by body segment, tend to present differences in the ranking of injury occurrence by anatomical site; these differences can be explained by their playing habits and the biomechanical characteristics of their golf swing. Many of these injuries can be prevented by a preseason, and year-round, sport-specific conditioning programme including: (i) muscular strengthening, flexibility and aerobic exercise components; (ii) a short, practical, pre-game warm-up routine; and (iii) the adjustment of an individual's golf swing to meet their physical capacities and limitations through properly supervised golf lessons. Finally, the correct selection of golf equipment and an awareness of the environmental conditions and etiquette of golf can also contribute to making golf a safe and enjoyable lifetime activity.Sports Medicine 08/1998; 26(1):43-57. · 5.16 Impact Factor -
Article: Regional variation in adipose tissue insulin action and GLUT4 glucose transporter expression in severely obese premenopausal women.
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ABSTRACT: Insulin action and GLUT4 expression were examined in adipose tissue of severely obese premenopausal women undergoing gastrointestinal surgery. Fat samples were taken from three different anatomical regions: the subcutaneous abdominal site, the round ligament (deep abdominal properitoneal fat), and the greater omentum (deep abdominal intraperitoneal fat). The stimulatory effect of insulin on glucose transport and the ability of the hormone to inhibit lipolysis were determined in adipocytes isolated from these three adipose depots. Insulin stimulated glucose transport 2-3 times over basal rates in all adipocytes. However, round ligament adipose cells showed a significantly greater responsiveness to insulin when compared to subcutaneous and omental adipocytes. Round ligament fat cells also displayed the greatest sensitivity and maximal antilipolytic response to insulin. We also investigated whether regional differences in fat cell insulin-stimulated glucose transport were linked to a differential expression of the GLUT4 glucose transporter. GLUT4 protein content in total membranes was 5 and 2.2 times greater in round ligament adipose tissue than in subcutaneous and omental fat depots, respectively. Moreover, GLUT4 mRNA levels were 2.1 and 3 times higher in round ligament than in subcutaneous or omental adipose tissues, respectively. Adipose tissue GLUT4 protein content was strongly and negatively associated (r = -0.79 to -0.89, p < 0.01) with the waist-to-hip ratio but not with total adiposity. In conclusion, these results demonstrate the existence of site differences in adipose tissue insulin action in morbidly obese women. The greater insulin effect on glucose transport in round ligament adipocytes was associated with a higher expression of GLUT4 when compared to subcutaneous abdominal and omental fat cells. Moreover, despite the regional variation in GLUT4 expression, an increased proportion of abdominal fat was found to be associated with lower levels of GLUT4 in all adipose regions investigated.Diabetologia 06/1997; 40(5):590-8. · 6.81 Impact Factor -
Article: Negative energy balance with exercise in identical twins: plasma glucose and insulin responses.
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ABSTRACT: The effects of long-term (93 days) negative energy balance on plasma glucose and insulin were investigated by means of exercise with constant energy intake in seven pairs of young sedentary male identical twins. Results showed a significant decrease in fasting (-24%, P < 0.02) and postprandial insulin (-16%, P < 0.05). Fasting and postprandial plasma glucose and glucagon were not modified. Mean glucose disposal rate measured during a euglycemic-hyperinsulinemic clamp performed in five twin pairs was increased by 34% (P = 0.13). No significant intrapair similarity was found for the responses of fasting and postprandial insulin levels and of glucose disposal rate. Changes in glucose disposal rate were significantly greater in high compared with low losers for computerized tomography-measured abdominal visceral fat (3.0 +/- 1.1 vs. 0.3 +/- 0.5 mg x kg(-1) x min(-1), P < 0.05) despite similar losses in total body fat. We conclude that 1) a long-term negative energy balance generated by exercise training significantly reduces plasma insulin levels, whereas insulin sensitivity tends to be improved; 2) training-induced changes in insulin sensitivity are associated with changes in abdominal visceral fat; and 3) data from this experiment conducted with a small number of twin pairs suggest that the genotype does not seem to be a major determinant of the changes in insulin levels and sensitivity brought about by negative energy balance with exercise.The American journal of physiology 02/1997; 272(2 Pt 1):E248-54. -
Article: Associations between 12 year changes in body fatness and lipoprotein-lipid levels in men and women of the Québec Family Study.
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ABSTRACT: To investigate the associations between 12 year changes in body composition, subcutaneous fat distribution vs changes in plasma lipoprotein-lipid levels. 12 year prospective study. A sample of 95 women and 93 men of the Québec Family Study initially tested in 1980. Various body fatness variables as well as fasting plasma lipoprotein-lipid concentrations performed both in 1980 and 1992. In both 1980 and 1992, a high body fat mass and an elevated accumulation of subcutaneous trunk fat were associated with a significant deterioration in the plasma lipoprotein-lipid profile. Furthermore, correlation analysis performed on differences noted during the 12 years follow-up revealed significant associations between changes in body fat mass and in plasma cholesterol [r = 0.52, P < 0.0005] in women. In both men and women, an increased body fat mass was associated with an increased CHOL/HDL-cholesterol ratio [r = 0.37, P < 0.01 (men) and r = 0.54, P < 0.0005 (women)]. Correlations between changes in fat mass and plasma lipids were generally of higher magnitude in women than in men. Changes in subcutaneous trunk fat were associated with changes in plasma HDL-chol levels (r = -0.22, P < 0.05) in men whereas in women, changes in trunk adiposity were related to changes in both plasma CHOL (r = 0.25, P < 0.05) and TG (r = 0.32, P < 0.005) levels. These results support the notion that the increased adiposity observed among aging adult men and women is a significant component of the deterioration in the plasma lipoprotein-lipid profile noted over a 12 year follow-up period.International Journal of Obesity 12/1996; 20(12):1081-8. · 4.69 Impact Factor -
Article: Overfeeding in identical twins: 5-year postoverfeeding results.
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ABSTRACT: From a total of 12 pairs of young male identical twins who were overfed by an estimated 84,000 kcal over a period of 100 days, several pairs (eight to 11, depending on variables) were remeasured for body weight, body composition with the underwater weighing technique, regional fat distribution from skinfolds, girths, computed tomography (CT) fat areas in the abdominal region, and fasting plasma glucose, insulin, total cholesterol, high-density lipoprotein (HDL) cholesterol, and triglycerides 4 months and 5 years after completion of the overfeeding protocol. At 4 months, the twins had lost approximately 7 of 8 kg that they had gained with overfeeding. However, 5 years later, body weight had increased by 5 kg over the preoverfeeding level. Fluctuations in fat mass were greater than those in fat-free mass. The younger twins gained approximately twice as much as the older twins in the late recovery period, a difference attributed to the late phase of growth in body mass in the former. Upper-body fat was reduced at 4 months of follow-up study, but was increased in the late recovery phase. All blood values were normalized in the postoverfeeding periods. A within-pair resemblance was generally observed for the changes noted in the recovery periods, but it was more striking when variations between preoverfeeding and 4-month or 5-year values were considered. We conclude from these observations that there were no persistent effects of exposure to the overfeeding protocol over the expected age-associated increases in body mass, body fat, upper-body fat, abdominal visceral fat (AVF), and metabolic variables predictive of risk for common diseases in individuals of normal body weight and with no family history of obesity. The intrapair resemblance suggests that the genotype contributes to the alterations observed in the recovery from overfeeding and in the age-associated changes.Metabolism 09/1996; 45(8):1042-50. · 2.66 Impact Factor -
Article: Golf Injury Characteristics: A Survey From 528 Golfers 389
Medicine & Science in Sports & Exercise 04/1996; 28(5):65. · 4.43 Impact Factor -
Article: Electrical stimulation-induced changes in performance and fiber type proportion of human knee extensor muscles.
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ABSTRACT: The purpose of the present study was to look at the changes in the performance of human knee extensor muscles (KEM) induced by 6 weeks of low-frequency (8 Hz) electrical stimulation (LFES). KEM performance of 20 sedentary (before and after stimulation), ten active, and five endurance-trained subjects was evaluated during 25 consecutive 10-s isometric contractions, each separated by a rest period of 5 s. The mean force maintained during six consecutive 10-s contractions was expressed as a relative percentage of that of the first contraction. The mean performance of the first series of six contractions was not altered in response to stimulation, whereas that of the other four series was significantly increased. No significant difference was noted among the three groups in terms of KEM performance during the first series of six contractions. However, after the first series of six contractions, KEM performance of endurance-trained subjects was better in comparison to the other groups. Citrate synthase (CS) activity, capillary number per type IIA and IIB fibers, and the percentage of type IIA muscle fibers determined from vastus lateralis samples were significantly increased in response to the stimulation protocol. No significant change was observed in the proportion or capillary number of type I fibers, or in the areas of type I, IIA, and IIB fibers. The present study provides evidence that resistance to fatigue of human skeletal muscle can be significantly altered in response to 6 weeks of transcutaneous low-frequency electrical stimulation. The improvement in KEM resistance to fatigue of the sedentary subjects was such that, at the end of the stimulation protocol, resistance to fatigue was similar to that of active subjects. However, the ability of endurance-trained subjects to withstand fatigue was still superior compared to that of the other untrained or active subjects.European Journal of Applied Physiology and Occupational Physiology 02/1996; 74(4):311-7. -
Article: Body fatness in active individuals reporting low lipid and alcohol intake.
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ABSTRACT: To evaluate body fatness in subjects complying with common public health guidelines for lipid and alcohol intake as well as physical activity participation. A sample of 358 male subjects who participated in phase 1 of the Quebec Family Study. The association between adiposity, lipid and alcohol intake and physical activity participation was analyzed in the overall sample. A comparison of body fatness in individuals adhering or not to public health recommendations was also performed. Significant positive correlations were observed between the percentage of dietary energy as lipid and adiposity indicators. Accordingly, subjects classified as low-fat consumers displayed significantly lower levels of fat mass and subcutaneous adiposity compared to high-fat consumers. When subjects reporting low lipid and alcohol intake and regular participation in vigorous physical activities were compared to those exhibiting opposite behaviors, the between-group difference in subcutaneous adiposity was doubled and this was essentially explained by an increase in the difference for truncal subcutaneous adiposity. These results indicate that the adherence to a lifestyle characterized by high-fat and alcohol intake as well as sedentariness promotes fat gain, particularly in the trunk area.European Journal of Clinical Nutrition 12/1995; 49(11):824-31. · 2.46 Impact Factor -
Article: Regional variation in adipose tissue metabolism of severely obese premenopausal women.
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ABSTRACT: Lipolytic and lipoprotein lipase (LPL) activities were studied in isolated human adipocytes obtained from two intraabdominal depots (round ligament and omental) and from the subcutaneous abdominal region of nine severely obese premenopausal women (with body mass indices ranging from 37 to 51 kg/m2), aged 36 +/- 3 yr, undergoing gastrointestinal surgery. Both fat cell weight and LPL activity were significantly greater in round ligament adipose cells than in subcutaneous abdominal or in omental adipocytes (P < 0.05). The antilipolytic effect of insulin and the sensitivity to this hormone were also higher in round ligament adipose cells than in omental adipocytes (P < 0.05). Although epinephrine initiated a similar biphasic profile of response in all cell types, the catecholamine promoted a weaker inhibition of lipolysis in omental adipocytes than in subcutaneous abdominal adipose cells (P < 0.05). In addition, a lack of regional variation was found in the maximal antilipolysis initiated by UK 14304 and the alpha 2-adrenoceptors was higher in both subcutaneous abdominal and round ligament fat cells than in omental adipocytes. Moreover, the maximal lipolytic response to isoproterenol or to agents acting at post-receptor levels was not different among fat depots. Finally, a lower beta-adrenergic lipolytic sensitivity associated with a reduced beta-adrenoceptor density was observed in round ligament as compared to omental adipose cells. These data suggest that in massively obese premenopausal women, omental and round ligament adipose tissues show distinct metabolic properties that may contribute to limit the impact of intraabdominal obesity.The Journal of Lipid Research 05/1995; 36(4):672-84. · 5.56 Impact Factor -
Article: Changes in plasma electrolytes and muscle substrates during short-term maximal exercise in humans.
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ABSTRACT: This study compared the effects of 3 short-term maximal exercise tests lasting 10, 30, and 90 sec upon blood volume, plasma electrolytes, glucose, glycerol, lactate and skeletal muscle ATP, PC, glycogen, and lactate concentrations. Seven sedentary male subjects were recruited and 5 of them were randomly assigned to each of the 3 protocols. The tests were performed on a modified ergocycle at workloads of 0.9, 0.075, and 0.05 kp.kg-1 body mass, respectively. Muscle biopsies were taken from the vastus lateralis before and immediately after each exercise. Venous blood samples were collected before, immediately after, and during the recovery (5, 20, 60, and 120 min). Plasma volume decreased during the 30- and 90-sec tests and was increased in all tests after 60 min of recovery. Plasma K+ increased during all tests and returned to normal values 5 min postexercise, except after the 90-sec test where it fell below resting values. Plasma Na+ and Cl- were unaffected. Blood lactate increased in all tests, glucose increased after the 90-sec test, and glycerol increased after the 30- and 90-sec tests. All 3 tests brought relatively similar changes in muscle ATP, PC, and glycogen while muscle lactate changes were related to exercise duration. These results suggest that a normal hydration status is important for a subject undergoing short training bouts, and that high-intensity tests of short duration do not require a special nutritional regimen to enhance glycogen reserves.Canadian journal of applied physiology = Revue canadienne de physiologie appliquée 04/1995; 20(1):89-101. · 1.30 Impact Factor -
Article: Plasma glucose, insulin, and glucagon before and after long-term overfeeding in identical twins.
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ABSTRACT: Plasma glucose, insulin, and glucagon levels were measured before and after long-term overfeeding (4.2 MJ/d during a 100-day period) in 24 lean adults (12 pairs of monozygotic twins). Fasting plasma glucose, insulin, and glucagon were significantly increased by overfeeding. During a 75-g oral glucose tolerance test (OGTT), no major alteration in glucose tolerance was observed and insulin area under the curve was increased. During a meal test, insulin and glucagon areas under the curve were increased. The pre-overfeeding values for glucose, insulin, and glucagon (fasting and areas) were not correlated with the gains in body weight and in fat mass. However, fasting glucagon before overfeeding was positively correlated with the gains in abdominal visceral fat and in femoral fat. The changes with overfeeding in insulin area during the OGTT were positively correlated with the changes in total subcutaneous fat, even after adjustment for total body fat gain. Significant twin intrapair similarity was observed for fasting plasma glucagon before overfeeding and for the changes in fasting insulin and glucagon with overfeeding. These results indicate that (1) in response to long-term overfeeding, both fasting insulin and glucagon are increased; (2) initial levels of glucose, insulin, and glucagon do not predict the gains in body weight and total body fat during overfeeding, but are related to changes in indicators of fat topography; (3) the changes in total subcutaneous fat represent an important correlate of insulin changes with overfeeding; and (4) the genotype could be an important determinant of insulin and glucagon responses to a prolonged positive-energy-balance period.Metabolism 02/1995; 44(1):96-105. · 2.66 Impact Factor -
Article: Human skeletal muscle adaptation in response to chronic low-frequency electrical stimulation.
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ABSTRACT: The purpose of the study was to verify the influence of several weeks of chronic low-frequency electrical stimulation (LFES) on the metabolic profile and functional capacity of human skeletal muscle. Knee extensor muscles (KEM) of eight subjects were electrically stimulated at 8 Hz for 8 h/day and 6 days/wk. Vastus lateralis muscle samples were taken before, after 4 wk, and after 8 wk of LFES, and activities of anaerobic (creatine kinase, phosphofructokinase, glyceraldehyde-3-phosphate dehydrogenase) and aerobic-oxidative (citrate synthase, 3-hydroxyacyl-CoA dehydrogenase, cytochrome-c oxidase) enzyme markers were determined. KEM dynamic performance was also assessed before, after 4 wk, and after 8 wk of LFES. Activity levels of anaerobic enzymes were not altered, whereas the activity levels of citrate synthase (29%),3-hydroxyacyl-CoA dehydrogenase (22%), and cytochrome-c oxidase (25%) were significantly increased after 4 wk of LFES but were not further increased after 4 additional wk of LFES. KEM performance was also improved (P < 0.05) but leveled off after 4 wk of LFES. Although significant changes were observed, the results of the present study suggest that the muscle characteristics investigated in the current study have a limited capacity of adaptation in response to this form of chronic LFES.Journal of Applied Physiology 10/1994; 77(4):1885-9. · 3.75 Impact Factor -
Article: The response to exercise with constant energy intake in identical twins.
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ABSTRACT: Seven pairs of young adult male identical twins completed a negative energy balance protocol during which they exercised on cycle ergometers twice a day, 9 out of 10 days, over a period of 93 days while being kept on a constant daily energy and nutrient intake. The total energy deficit caused by exercise above the estimated energy cost of body weight maintenance reached 244 +/- 9.8 MJ (Mean +/- SEM). Baseline energy intake was estimated over a period of 17 days preceding the negative energy balance protocol. Mean body weight loss was 5.0 kg (SEM = 0.6) (p < 0.001) and it was entirely accounted for by the loss of fat mass (p < 0.001). Fat-free mass was unchanged. Body energy losses reached 191 MJ (SEM = 24) (p < 0.001) which represented about 78% of the estimated energy deficit. Subcutaneous fat loss was slightly more pronounced on the trunk than on the limbs as estimated from skinfolds, circumferences, and computed tomograply (CT). The reduction in CT-assessed abdominal visceral fat was quite striking, from 81 cm2 (SEM = 5) to 52 cm2 (SEM = 6) (p < 0.001). At the same submaximal power output level, subjects oxidized more lipids than carbohydrates after the program as indicated by the changes in the respiratory exchange ratio (p < or = 0.05). Intrapair resemblance was observed for the changes in body weight (p < 0.05), fat mass (P < 0.01), percent fat (p < 0.01), body energy content (p < 0.01), sum of 10 skinfolds (p < 0.01), abdominal visceral fat (p < 0.01), fasting plasma triglycerides (p < 0.05) and cholesterol (p < 0.05), maximal oxygen uptake (p < 0.05), and respiratory exchange ratio during submaximal work (p < 0.01). We conclude that even though there were large individual differences in response to the negative energy balance and exercise protocol, subjects with the same genotype were more alike in responses than subjects with different genotypes particularly for body fat, body energy, and abdominal visceral fat changes. High lipid oxidizers and low lipid oxidizers during submaximal exercise were also seen despite the fact that all subjects had experienced the same exercise and nutritional conditions for about three months.Obesity research 09/1994; 2(5):400-10. · 4.95 Impact Factor -
Article: Thyroid hormones and thyrotropin variations during long term overfeeding in identical twins.
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ABSTRACT: The aim of this study was to evaluate variations in plasma thyroid hormones and TSH during a standardized long term overfeeding protocol (4.2 megajoules/day [corrected] during a 100-day period) in 24 lean adults (12 pairs of monozygotic twins) and to assess their relationships with body composition and resting metabolic rate (RMR) changes. Compared to preoverfeeding values, basal plasma T3 concentrations were increased on day 25, but not later; basal plasma T4 and free T4 (FT4) concentrations were unchanged; basal plasma rT3 concentrations were persistently decreased throughout the entire protocol; and the TSH response to TRH stimulation was persistently enhanced. The TSH response to TRH before overfeeding was positively correlated with the changes in RMR with overfeeding (r = -0.53; P < 0.01). No association was found between changes in basal plasma T3 concentrations and changes in RMR. However, changes in basal T3 were positively related to changes in body weight (r = 0.46; P < 0.05). A significant within-pair similarity was found for changes in T4 and FT4 with overfeeding (P < 0.05). We conclude that 1) during overfeeding, the early increase in T3 concentrations is a transitory phenomenon, whereas the decrease in rT3 concentrations and the increased TSH response to TRH are more sustained; 2) the TSH responsiveness to TRH stimulation could be a predictor of the changes in RMR during times of increased energy intake; 3) there is no evidence for a direct role of T3 in the adaptation of resting energy expenditure during a long term overfeeding protocol; and 4) the genotype could be involved in the changes in T4 and FT4 during a prolonged positive energy balance period.Journal of Clinical Endocrinology & Metabolism 08/1994; 79(2):547-53. · 6.50 Impact Factor -
Article: Are gender differences in cardiovascular disease risk factors explained by the level of visceral adipose tissue?
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ABSTRACT: It has been suggested that the lower prevalence of cardiovascular disease in women before menopause in comparison with men may be explained by differences in body fat distribution, plasma lipoprotein levels and indices of plasma glucose-insulin homeostasis. Thus, gender differences in visceral adipose tissue accumulation measured by computed tomography and metabolic variables were studied in 80 men and 69 pre-menopausal women, aged 23-50 years. Despite the fact that women had higher levels of total body fat (p < 0.0001), they displayed lower areas of abdominal visceral adipose tissue (p < 0.06) and a lower ratio of abdominal visceral to mid-thigh adipose tissue areas than men (p < 0.0001). After adjustment for body fat mass, women generally displayed a more favourable risk profile than men which included higher plasma HDL2-cholesterol and lower plasma insulin, apolipoprotein B and triglyceride levels (p < 0.01). Metabolic variables adjusted for body fat mass were then compared between genders after control for differences in abdominal visceral adipose tissue area. After such controls, variables related to plasma glucose-insulin homeostasis were no longer significantly different between men and women. Gender differences for plasma concentrations of triglyceride, apolipoprotein B and the ratio of HDL2-cholesterol/HDL3-cholesterol also disappeared, whereas plasma concentrations of HDL-cholesterol, HDL2-cholesterol as well as the ratio of HDL-cholesterol/total cholesterol remained significantly higher in women than in men (p < 0.01). These results suggest that abdominal visceral adipose tissue is an important correlate of gender differences in cardiovascular disease risk. However, additional factors are likely to be involved in gender differences in plasma HDL-cholesterol levels.Diabetologia 08/1994; 37(8):757-64. · 6.81 Impact Factor -
Article: Evidence for a role of insulin in the regulation of abdominal adipose tissue lipoprotein lipase response to exercise training in obese women.
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ABSTRACT: Abdominal and femoral adipose tissue lipoprotein lipase (AT-LPL) activities were measured in ten obese premenopausal women (mean age 35 +/- 5 years) who took part in a six month endurance exercise training programme. The programme involved four to five 90 min training sessions per week at about 50 to 55% of maximal endurance power (VO2max). Before training, the ratio of insulin to glucose area measured during an oral glucose tolerance test (OGTT) was significantly correlated with fat mass (r = 0.72, P < 0.05) as well as with abdominal AT-LPL activity (r = 0.69, P < 0.05). The training programme induced a significant increase in VO2max (P < 0.05) whereas no significant change in the mean body composition was observed. Abdominal as well as femoral AT-LPL activities were significantly reduced after the exercise training programme (P < 0.05) whereas plasma post-heparin (PH) LPL activity was significantly increased by training (P < 0.05). No significant association was observed between changes in VO2max and in body composition parameters and changes in abdominal or femoral AT-LPL activities. However, changes in insulin sensitivity, as estimated by changes in the insulin area/glucose area ratio were positively correlated with changes in abdominal AT-LPL activity expressed on a per cell (r = 0.72, P < 0.05) or per surface area (r = 0.81, P < 0.01) basis. These results suggest that the reduction in AT-LPL activity in both fat depots following endurance training in obese women can occur despite the lack of significant decrease in body weight and average fat cell size.(ABSTRACT TRUNCATED AT 250 WORDS)International Journal of Obesity 05/1993; 17(5):255-61. · 4.69 Impact Factor -
Article: Electrical stimulation-induced changes in skeletal muscle enzymes of men and women.
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ABSTRACT: The purpose of the present study was to determine the effects of low-frequency electrical stimulation (LFES) on the skeletal muscle metabolic profile of men and women. The knee extensor muscles of sedentary men (N = 16) and women (N = 10) were submitted to 3 h.d-1 of 8-Hz neuromuscular electrical stimulation with the use of a portable stimulator (Respond II, Medtronic), 6 d.wk-1 for 6 wk. Enzyme activity levels of creatine kinase (CK), hexokinase (HK), glyceraldehydephosphate dehydrogenase (GAPDH), 3-hydroxyacyl CoA dehydrogenase (HADH), citrate synthase (CS), phosphofructokinase (PFK), and cytochrome c oxidase (COX) were determined in vastus lateralis muscle samples taken before and after the LFES protocol. The analyses of variance revealed no change in CK and in GAPDH. However, a small decrease in PFK activity, the rate-limiting enzyme of glycolysis, was observed in female (8%) and in male subjects (10%), but it reached significance in males only (P < 0.05). The activity level of HK, a regulatory enzyme of the skeletal muscle glucose phosphorylation (HK), increased significantly in female subjects only (36%; P < 0.01) in response to the stimulation protocol. Activity level of marker enzymes of the Krebs cycle (CS) and of the electron-transfert chain (COX) significantly increased in males (18% and 16%; P < 0.05) as well as in females (31% and 19%; P < 0.05). Increment in the marker enzyme activity of the fatty acid oxidation (HADH) was significant in female subjects (30%; P < 0.01) and, although significant, rather modest in male subjects (12%; P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)Medicine & Science in Sports & Exercise 12/1992; 24(11):1252-6. · 4.43 Impact Factor -
Article: Overfeeding and energy expenditure in humans.
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ABSTRACT: The effect of overfeeding on energy expenditure was investigated in 23 young men subjected to a 353-MJ energy intake surplus over 100 d. The major part of this excess (222 MJ) was stored as body energy. The increase in energy cost of weight maintenance amounted to 52 MJ and was proportional to body weight gain. When it was added to the obligatory cost of fat and fat-free mass gains, the overall increase in energy expenditure amounted to a mean of 100 MJ. Four months after overfeeding, subjects had lost 82%, 74%, and 100% of the overfeeding gain in body weight, fat mass, and fat-free mass, respectively. We conclude that 1) in response to overfeeding, two-thirds of the excess energy intake is stored as body energy; 2) overfeeding induces an increase in energy cost of weight maintenance proportional to body weight gain, and 3) preoverfeeding energy balance tends to be restored when nonobese individuals return to their normal daily-life habits.American Journal of Clinical Nutrition 12/1992; 56(5):857-62. · 6.67 Impact Factor
Top co-authors
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Institutions
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1987–2009
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University Laval
- • Département d'Education Physique
- • Faculté de Médecine
- • Département de Médecine
Québec, Quebec, Canada
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1997
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Hôtel-Dieu de Paris – Hôpitaux universitaires Paris Centre
Paris, Ile-de-France, France
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1989
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University of Vermont
- College of Medicine
Burlington, VT, USA
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