Jérémy Vanhelst

Comparison of two ActiGraph accelerometer generations in the assessment of physical activity in free living conditions

BackgroundThe aim of this study was to compare physical activity measured using GT1M ActiGraph and GT3X ActiGraph accelerometers in free living conditions.FindingsTwenty-five adults wore GT1M and GT3X Actigraph accelerometers simultaneously during a typical weekday of activity. Data were uploaded from the monitor to a computer at the end of test (one day). Previously established thresholds were used for defining time spent at each level of physical activity, physical activity was assessed at varying intensities comparing data from the two accelerometers by ANOVA and Bland and Altman statistical analysis. The concordance correlation coefficient between accelerometers at each intensity level was 0.99. There were no significant differences between accelerometers at any of the activity levels. Differences between data obtained in minutes with the GT1M accelerometer and the GT3X monitor were to 0.56, 0.36, 0.52 and 0.44% for sedentary, light, moderate and vigorous, respectively. The Bland and Altman method showed good agreement between data obtained for the two accelerometers.ConclusionsFindings suggest that the two accelerometers provided similar results and therefore the GT3X may be used in clinical and epidemiological studies without additional calibration or validation studies.

Muscular fitness, fatness and inflammatory biomarkers in adolescents

Metabolic and cardiovascular diseases involve an inflammatory process that begins early in life. Muscular fitness has been inversely associated with cardiometabolic risk factors in adolescents, including inflammatory biomarkers. More research is needed to evaluate whether the influence of muscular fitness on chronic inflammation is independent of cardiorespiratory fitness and fatness.

Calibration of the RT3 accelerometer for various patterns of physical activity in children and adolescents

Abstract The aim of this study was to determine thresholds for various intensities of physical activity in children and adolescents using the RT3 accelerometer. Forty healthy participants aged 10–16 years were recruited to the study. To validate the RT3 accelerometer data, an independent sample of 20 children and adolescents aged 10–16 years performed the same activities. Accelerometer data, heart rate, and oxygen consumption were measured at nine levels of physical activity, which varied in intensity: sedentary, light, moderate, and vigorous. Age and sex did not affect thresholds. The activity categories and accelerometer counts were: sedentary activity, 0–40 counts · min−1; light activity, 41–950 counts · min−1; moderate activity, 951–3410 counts · min−1; and vigorous activity, >3410 counts · min−1, respectively. These thresholds were considered valid as the difference between threshold values obtained using two independent groups of children was not significant. This study has established threshold values for various physical activities and enables the RT3 accelerometer to be used to quantify the duration of various levels of activity in adolescents under free-living conditions.

Prevalence of overweight in adolescents with intellectual deficiency. Differences in socio-educative context, physical activity and dietary habits §

The study investigates the prevalence of overweight and obesity in a population of intellectually disabled (ID) adolescents. An observational study was conducted on a group of 410 ID children, living in France. Overweight and obesity, defined according to international standards, were analyzed and related to demographic and sociological parameters, educational care, physical activity and dietary habits. The study highlighted a high prevalence of overweight and obesity (19.0%) in ID adolescents and 22.5% in oldest teenagers, age 15-20 y. This observation was more likely in medico-educative institutes (25.1%) than in general schools (12.3%). Average time spent in physical activity was 4.5 h/week, compared with 3.5 h/week in obese subjects. Time spent in sedentary behavior was 26.6 h/week for the whole population, compared with 18.6 h/week in obese adolescents. Meals were ingested regularly, and adherence to eating breakfast was good. However, snacks and soft drinks were consumed between and during meals by 66.5% of subjects. Overweight in young ID appeared to be related to parental overweight. Even though ID adolescents receive a balanced diet and practice sport regularly, they exhibit a high prevalence for overweight and obesity. In subjects more than 15 years of age, enrollment in medico-educative institutes and parental overweight were contributory factors to poor weight status.

Comparison of uniaxial and triaxial accelerometry in the assessment of physical activity among adolescents under free-living conditions: the HELENA study

BackgroundDifferent types of devices are available and the choice about which to use depends on various factors: cost, physical characteristics, performance, and the validity and intra- and interinstrument reliability. Given the large number of studies that have used uniaxial or triaxial devices, it is of interest to know whether the different devices give similar information about PA levels and patterns. The aim of this study was to compare physical activity (PA) levels and patterns obtained simultaneously by triaxial accelerometry and uniaxial accelerometry in adolescents in free-living conditions.MethodsSixty-two participants, aged 13-16 years, were recruited in this ancillary study, which is a part of the Healthy Lifestyle in Europe by Nutrition in Adolescence (HELENA). All participants wore a uniaxial accelerometer (ActiGraph GT1M®, Pensacola, FL) and a triaxial accelerometer (RT3®, Stayhealthy, Monrovia, CA) simultaneously for 7 days. The patterns were calculated by converting accelerometer data output as a percentage of time spent at sedentary, light, moderate, and vigorous PA per day. Analysis of output data from the two accelerometers were assessed by two different tests: Equivalence Test and Bland & Altman method.ResultsThe concordance correlation coefficient between the data from the triaxial accelerometer and uniaxial accelerometer at each intensity level was superior to 0.95. The ANOVA test showed a significant difference for the first three lower intensities while no significant difference was found for vigorous intensity. The difference between data obtained with the triaxial accelerometer and the uniaxial monitor never exceeded 2.1% and decreased as PA level increased. The Bland & Altman method showed good agreement between data obtained between the both accelerometers (p < 0.05).ConclusionsUniaxial and triaxial accelerometers do not differ in their measurement of PA in population studies, and either could be used in such studies.

Reliability of the RT3 accelerometer for measurement of physical activity in adolescents

Abstract The aim of this study was to assess the reliability of the RT3 accelerometer under conditions of normal physical activity. Sixty healthy individuals (30 boys, 30 girls) aged 10–16 years wore two accelerometers while performing different structured physical activities. The accelerometers were synchronized and data were recorded every minute during nine 15-min sessions of physical activity that varied in intensity from sedentary (watching television, playing video games) to vigorous (running on a treadmill at different speeds). Intra-instrument coefficients of variation (CV) were assessed using the formula CV = standard deviation of the measure × 100/mean of the measure. The intra-instrument coefficient of variation was higher for sedentary (17%) and light activity (16.2%) than moderate (9.3%) and vigorous activity (6.6%). These results confirmed the poor reliability of the RT3 for activity of low magnitude and frequency that was demonstrated in studies using a shaker.

New validated thresholds for various intensities of physical activity in adolescents using the Actigraph accelerometer.

The aim of this study was to determine and validate the new thresholds for various intensities of physical activity in adolescents using the Actigraph accelerometer. Sixty healthy participants aged 10–16 years were recruited. Forty participants participated in the calibration study whereas the others participated in the validation study. Accelerometer data, heart rate, and oxygen consumption were measured at nine levels of physical activity which varied in intensity: sedentary, light, moderate and vigorous. The activity categories and accelerometer counts were sedentary activity, 0–400 counts/min; light activity, 401–1900 counts/min; moderate activity, 1901–3918 counts/min; and vigorous activity, greater than 3918 counts/min, respectively. This study establishes new threshold values for various physical activities that can be used for population-based studies in adolescents.

Clustering of Multiple Lifestyle Behaviors and Health-related Fitness in European Adolescents

OBJECTIVE To explore the clustering of different lifestyle behaviors and whether this clustering differs by gender, age, and health-related fitness. DESIGN Healthy Lifestyle in Europe by Nutrition in Adolescence (HELENA) cross-sectional study. SETTING Ten European cities. PARTICIPANTS A total of 2,084 adolescents (12.5-17.5 years). MAIN OUTCOME MEASURES Four lifestyle behaviors were assessed by self-administered questionnaires: moderate to vigorous physical activity, homework time, screen time, and diet. Health-related fitness components (aerobic capacity, strength, speed-agility, and body composition) were assessed. ANALYSIS Hierarchical method and κ-means cluster analysis. Analysis of variance tests. RESULTS Five clusters were identified: Healthy diet and Active, Healthy diet and Academic, Healthy diet and Inactive, Unhealthy diet and Screen user, and Unhealthy diet and Active. Younger adolescents were more active and followed a healthier diet than older adolescents. Older boys devoted more time to screen use, whereas older girls devoted more time to homework. Boys in the Healthy diet and Active cluster presented higher aerobic capacity and speed-agility, whereas girls presented higher aerobic capacity, strength, and speed-agility. CONCLUSIONS AND IMPLICATIONS Clustering of different lifestyle behaviors is observed. Different healthy lifestyles do not always come together and clusters are associated with gender, age, and health-related fitness, but not with body composition. These differences need to be considered when developing intervention strategies for the prevention of unhealthy habits.

Overweight in intellectually-disabled population: physical, behavioral and psychological characteristics.

Intellectually disabled (ID) people are at high risk of overweight and obesity. Prevalence and risk factors were assessed in a French population of ID adults attending specialized institutions, using a questionnaire focusing on demographic characteristics, physical activities, food habits and self-awareness about body and health. Data analysis included descriptive statistics, univariate and multivariate regression. Overall, 570 participants were included in the analysis (59% male), aged 19-59 years. The mean body mass index (BMI) was 24.9 kg/m(2); 45.6% of participants were overweight (BMI ≥ 25), including 17.2% who were obese (BMI ≥ 30). Participants practiced sports for 5.7h/week on average and were sedentary for 21.8h/week (time spent in front of some kind of screen). Most participants had food and self-care habits usually regarded as healthy. Eighty percent of them felt unhappy with their body and their physical capacities, but otherwise expressed a rather good opinion of themselves. Bivariate and multivariate analyses showed that some behavioral habits were associated with a reduced incidence of overweight and/or obesity, such as regular sport practice outside the institution, good personal body care or alcohol avoidance. The strongest risk factor was gender. Women were much more at risk than men of being overweight (53.9% versus 39.9%) and obese (28.2% versus 9.5%). Results suggest numerous ways to improve the health of institutionalized ID adults, related to sports education, nutrition and self-care, with particular attention paid to women.

Effect of child health status on parents’ allowing children to participate in pediatric research

BackgroundTo identify motivational factors linked to child health status that affected the likelihood of parents’ allowing their child to participate in pediatric research.MethodsParents were invited to return their completed questionnaires anonymously to assess motivational factors and factors that might improve participation in pediatric research.ResultsOf 573 eligible parents, 261 returned the completed questionnaires. Of these, 126 were parents of healthy children (group 1), whereas 135 were parents of sick children who were divided into two groups according to the severity of their pathology, i.e., 99 ambulatory children (group 2) and 36 nonambulatory children (group 3). The main factor motivating participation in a pediatric clinical research study was “direct benefits for their child” (87.7%, 100%, and 100% for groups 1, 2, and 3, respectively). The other factors differed significantly between the three groups, depending on the child’s health status (all p < 0.05). Factors that might have a positive impact on parental consent to the participation of their child in a pediatric clinical research study differed significantly (χ2 test, all p ≤ 0.04), depending on the child’s health status. The main factor was “a better understanding of the study and its regulation” for the healthy children and ambulatory sick children groups (31.2% and 82.1%, respectively), whereas this was the third factor for the nonambulatory sick children group (50%).ConclusionsInnovative strategies should be developed based on a child’s health status to improve information provision when seeking a child’s participation in pediatric research. Parents would like to spend more time in discussions with investigators.