Marie-Eve Mathieu

Associations of sedentary behavior, sedentary bouts and breaks in sedentary time with cardiometabolic risk in children with a family history of obesity.

Background Although reports in adults suggest that breaks in sedentary time are associated with reduced cardiometabolic risk, these findings have yet to be replicated in children. Purpose To investigate whether objectively measured sedentary behavior, sedentary bouts or breaks in sedentary time are independently associated with cardiometabolic risk in a cohort of Canadian children aged 8–11 years with a family history of obesity. Methods Data from 286 boys and 236 girls living in Quebec, Canada, with at least one biological parent with obesity (QUALITY cohort) were collected from 2005–2008, and analyzed in 2013. Sedentary behavior, light and moderate-to-vigorous physical activity were measured over 7 days using accelerometry. Leisure time computer/video game use and TV viewing over the past 7 days were self-reported. Outcomes included waist circumference, body mass index Z-score, fasting insulin, fasting glucose, triglycerides, HDL-cholesterol, C-reactive protein and a continuous cardiometabolic risk score. Results After adjustment for confounders, breaks in sedentary time and the number of sedentary bouts lasting 1–4 minutes were associated with reduced cardiometabolic risk score and lower BMI Z-score in both sexes (all p<0.05). The number of sedentary bouts lasting 5–9 minutes was negatively associated with waist circumference in girls only, while the number of bouts lasting 10–14 minutes was positively associated with fasting glucose in girls, and with BMI Z-score in boys (all p<0.05). Leisure time computer/video game use was associated with increased cardiometabolic risk score and waist circumference in boys, while TV viewing was associated with increased cardiometabolic risk, waist circumference, and BMI Z-score in girls (all p<0.05). Conclusions These results suggest that frequent interruptions in sedentary time are associated with a favourable cardiometabolic risk profile and highlight the deleterious relationship between screen time and cardiometabolic risk among children with a family history of obesity.

Physical activity vs. sedentary time: independent associations with adiposity in children

To investigate the independent associations between objectively measured levels of movement intensity (i.e. time spent sedentary and at light, moderate and vigorous intensities) and indicators of adiposity in a cohort of Canadian children.

Combined associations between moderate to vigorous physical activity and sedentary behaviour with cardiometabolic risk factors in children.

The objective of this study was to examine the combined associations between time spent in moderate- to vigorous-intensity physical activity (MVPA) and time spent sedentary in relation to cardiometabolic risk factors in a cohort of Canadian children. A cross-sectional study was conducted on 536 white children aged 8-10 years with at least 1 obese biological parent. Time spent in MVPA and sedentary behaviour over 7 days was measured using accelerometry and participants were stratified by tertiles. Daily screen time over 7 days was also self-reported by the child. Outcomes included waist circumference, systolic and diastolic blood pressure, fasting triglycerides, high-density lipoprotein cholesterol, and glucose concentrations. Analyses of covariance comparing tertiles of sedentary time/MVPA showed that higher levels of MVPA were associated with lower waist circumference, fasting triglycerides and diastolic blood pressure, and higher high-density lipoprotein (HDL) cholesterol, irrespective of sedentary time. In linear regression, MVPA was inversely associated with waist circumference and diastolic blood pressure and positively associated with HDL cholesterol, independent of covariates including sedentary time. In contrast, sedentary time was positively associated with diastolic blood pressure but after adjustment for MVPA the association was no longer statistically significant. Self-reported screen time was positively associated with waist circumference and negatively associated with HDL cholesterol independent of covariates including MVPA. Overall, a high level of MVPA was associated with reduced cardiometabolic risk in this sample of children, regardless of their amount of sedentary behaviour. The type of sedentary behaviour (i.e., screen time) might be more important than overall sedentary time in relation to cardiometabolic risk.

Contribution of the lean body mass to insulin resistance in postmenopausal women with visceral obesity : a Monet study.

Some insulin‐resistant obese postmenopausal (PM) women are characterized by an android body fat distribution type and higher levels of lean body mass (LBM) compared to insulin‐sensitive obese PM women. This study investigates the independent contribution of LBM to the detrimental effect of visceral fat (VF) levels on the metabolic profile. One hundred and three PM women (age: 58.0 ± 4.9 years) were studied and categorized in four groups on the basis of their VF (higher vs. lower) and lean BMI (LBMI = LBM (kg)/height (m2); higher vs. lower). Measures included: fasting lipids, glucose homeostasis (by euglycemic/hyperinsulinemic clamp technique and 2‐h oral glucose tolerance test (OGTT)), C‐reactive protein (CRP) levels, fat distribution (by computed tomography (CT) scan), and body composition (by dual‐energy X‐ray absorptiometry). Women in the higher VF/higher LBMI group had lower glucose disposal and higher plasma insulin levels compared to the other groups. They also had higher plasma CRP levels than the women in the lower VF/lower LBMI group. VF was independently associated with insulin levels, measures of glucose disposal, and CRP levels (P < 0.05). LBMI was also independently associated with insulin levels, glucose disposal, and CRP levels (P < 0.05). Finally, significant interactions were observed between LBMI and VF levels for insulin levels during the OGTT and measures of glucose disposal (P < 0.05). In conclusion, VF and LBMI are both independently associated with alterations in glucose homeostasis and CRP levels. The contribution of VF to insulin resistance seems to be exacerbated by increased LBM in PM women.

Cohort Profile: The Quebec Adipose and Lifestyle Investigation in Youth Cohort

Departement de pediatrie, Universite de Montreal, Montreal, Quebec, Canada, Centre de recherche du Centre Hospitalier Universitaire (CHU) Sainte-Justine, Montreal, Quebec, Canada, Departement de medecine sociale et preventive, Universite de Montreal, Montreal, Quebec, Canada, Centre de Recherche du Centre Hospitalier de l’Universite de Montreal, Montreal, Quebec, Canada, Division of Kinesiology, Faculty of Medicine, Universite Laval, Quebec, Canada, Departement d’education physique, Universite Laval, Quebec, Canada, Departement de radiologie, CHU Sainte-Justine, Montreal, Quebec, Canada, School of Dietetics and Human Nutrition, McGill University, Montreal, Quebec, Canada, Department of Epidemiology, Biostatistics and Occupational Health, McGill University, Montreal, Quebec, Canada, Department of Psychiatry, McGill University, Montreal, Quebec, Canada, Office of Senior Medical Advisor, First Nations Inuit Health Branch, Health Canada, Vancouver, British-Columbia, Canada, Departement de kinesiologie, Universite de Montreal, Montreal, Quebec, Canada, School of Public Health, University of Alberta, Edmonton, Alberta, Canada, Department of Psychology, Concordia University, Montreal, Quebec, Canada, Epidemiology and Biostatistics Unit, INRS-Institut Armand-Frappier, Laval, Quebec, Canada, Institut universitaire de cardiologie et de pneumologie de Quebec, Faculte de pharmacie, Universite Laval, Quebec, Canada, Department of Kinesiology and Physical Education, McGill University, Montreal, Quebec, Canada, McGill University Health Center Research Institute, Montreal, Quebec, Canada and Institut national de sante publique du Quebec, Montreal, Quebec, Canada

Physical Activity and Obesity: Biomechanical and Physiological Key Concepts

Overweight (OW) and obesity (OB) are often associated with low levels of physical activity. Physical activity is recommended to reduce excess body weight, prevent body weight regain, and decrease the subsequent risks of developing metabolic and orthopedic conditions. However, the impact of OW and OB on motor function and daily living activities must be taken into account. OW and OB are associated with musculoskeletal structure changes, decreased mobility, modification of the gait pattern, and changes in the absolute and relative energy expenditures for a given activity. While changes in the gait pattern have been reported at the ankle, knee, and hip, modifications at the knee level might be the most challenging for articular integrity. This review of the literature combines concepts and aims to provide insights into the prescription of physical activity for this population. Topics covered include the repercussions of OW and OB on biomechanical and physiological responses associated with the musculoskeletal system and daily physical activity. Special attention is given to the effect of OW and OB in youth during postural (standing) and various locomotor (walking, running, and cycling) activities.

Consumption of Added Sugars from Liquid but Not Solid Sources Predicts Impaired Glucose Homeostasis and Insulin Resistance among Youth at Risk of Obesity

Little is known about longitudinal associations between added sugar consumption (solid and liquid sources) and glucose-insulin homeostasis among youth. Caucasian children (8-10 y) with at least one obese biological parent were recruited in the QUébec Adipose and Lifestyle InvesTigation in Youth (QUALITY) cohort (n = 630) and followed-up 2 y later (n = 564). Added sugars were assessed by 3 24-h dietary recalls at baseline. Two-year changes were examined in multivariate linear regression models, adjusting for baseline level, age, sex, Tanner stage, energy intake, fat mass (dual-energy X-ray absorptiometry), and physical activity (7 d accelerometer). Added sugar intake in either liquid or solid sources was not related to changes in adiposity measures (fat mass, body mass index, or waist circumference). However, a higher consumption (10 g/d) of added sugars from liquid sources was associated with 0.04 mmol/L higher fasting glucose, 2.3 pmol/L higher fasting insulin, 0.1 unit higher homeostasis model assessment of insulin resistance (HOMA-IR), and 0.4 unit lower Matsuda-insulin sensitivity index (Matsuda-ISI) in all participants (P < 0.01). No associations were observed with consumption of added sugars from solid sources. Overweight/obese children at baseline had greater increases in adiposity indicators, fasting insulin, and HOMA-IR and decreases in Matsuda-ISI during those 2 y than normal-weight children. Consumption of added sugars from liquid or solid sources was not associated with changes in adiposity, but liquid added sugars were a risk factor for the development of impaired glucose homeostasis and insulin resistance over 2 y among youth at risk of obesity.

How are physical activity, fitness, and sedentary behavior associated with insulin sensitivity in children?

OBJECTIVE To describe the associations among moderate-to-vigorous physical activity (MVPA), fitness, sedentary behavior (SB), and insulin sensitivity (IS). RESEARCH DESIGN AND METHODS Data were drawn from the baseline assessment of the QUALITY cohort, which included 630 white youth (aged 8–10 years at recruitment), with at least one obese biological parent. IS was measured by two fasting indices (insulin, homeostasis model assessment of insulin resistance) and an oral glucose tolerance test (OGTT)–based index (Matsuda IS index [Matsuda-ISI]). Fitness was measured by Vo2peak; percent fat mass (PFM) was measured by dual-energy X-ray absorptiometry; 7-day MVPA was measured with accelerometry. SB indicators included average hours daily of self-report screen time (SBst), and average minutes daily at <100 counts/min from accelerometry (SBacc). Multivariable linear regression models were adjusted for age, sex, season, and puberty. RESULTS MVPA and SBacc were independently associated with IS, but this was no longer statistically significant after accounting for PFM. SBst was negatively associated with IS in girls only, even after controlling for physical activity (PA), fitness, and adiposity; for each additional hour of SBst daily, IS decreased by 4.6–5.6% across all IS indices. Fitness was positively associated with IS (measured by Matsuda-ISI) after accounting for PA, SB, and PFM; for every 1 unit increase in Vo2peak, Matsuda-ISI increased by approximately 1.0% (P < 0.05). CONCLUSIONS In children with an obese parent, PA and SBacc are associated with IS, but this association is mediated by adiposity. SBst is negatively associated with IS in girls, beyond its known impact on adiposity. Finally, fitness is independently associated with better IS measured by OGTT.

Globalization and modernization: an obesogenic combination

Animal research has well established that a link exists between variations in corticosteroids and the proneness to excess body fat accumulation. Accordingly, it is known that adrenalectomy is an efficient approach to counteract weight gain in most animal models of obesity. In humans, the association between variations in corticosteroids, its stress‐related environmental effects and the predisposition to obesity is more difficult to demonstrate. In this paper, we propose that this relationship is accentuated by globalization and modernization which favour a labour context imposing additional stress and changes in life habits promoting a positive energy balance. Our main hypothesis is that the increase in knowledge‐based work, and the decrease of quality and duration of sleep both induce an increase in cortisolaemia and glycaemia instability, which results in an increase in food intake, a reduction in energy expenditure and body fat gain. The authors of this paper believe that, from a socioeconomic perspective, globalization leads every nation of the world in conflict with itself and may consequently represent a real problem. On one hand, there are preoccupations related to productivity and money making. On the other hand, people have to adopt a daily lifestyle leading to hyperphagia and decreased energy expenditure in order to maintain their economic competitiveness.

Parental Misperception of Their Child's Body Weight Status Impedes the Assessment of the Child's Lifestyle Behaviors.

Objectives. To examine if distinct characteristics are associated with parental misclassification of underweight (UW), normal weight (NW), and overweight or obese (OWOB) children and the implications of misclassification on the parental evaluation of the childs lifestyle habits. Methods. Cross-sectional analysis (2004 sample) of the Quebec Longitudinal Study of Child Development (1998–2010) (n = 1,125). Results. 16%, 55%, and 77% of NW, UW and OWOB children were perceived inaccurately, respectively. Misperception was significantly higher in nonimmigrant parents of UW children, in highly educated parents of NW children and in NW and OWOB children with lower BMI percentiles. Erroneous body weight status identification impedes the evaluation of eating habits of all children as well as physical activity and fitness levels of UW and OWOB children. Conclusion. Parental misclassification of the childs body weight status and lifestyle habits constitutes an unfavorable context for healthy body weight management.