Relationship between temperament, nonresting energy expenditure, body composition, and physical activity in girls

Exercise-induced Changes in Central Adiposity During an RCT: Effect of Exercise Dose and Associations With Compensation

CONTEXT

Exercise can decrease central adiposity, but the effect of exercise dose and the relationship between central adiposity and exercise-induced compensation is unclear.

OBJECTIVE

Test the effect of exercise dose on central adiposity change and the association between central adiposity and exercise-induced weight compensation.

METHODS

In this ancillary analysis of a 6-month randomized controlled trial, 170 participants with overweight or obesity (mean ± SD body mass index: 31.5 ± 4.7 kg/m2) were randomized to a control group or exercise groups that reflected exercise recommendations for health (8 kcal/kg/week [KKW]) or weight loss and weight maintenance (20 KKW). Waist circumference was measured, and dual-energy X-ray absorptiometry assessed central adiposity. Predicted weight change was estimated and weight compensation (weight change - predicted weight change) was calculated.

RESULTS

Between-group change in waist circumference (control: .0 cm [95% CI, -1.0 to 1.0], 8 KKW: -.7 cm [95% CI, -1.7 to .4], 20 KKW: -1.3 cm [95% CI, -2.4 to -.2]) and visceral adipose tissue (VAT; control: -.02 kg [95% CI, -.07 to .04], 8 KKW: -.01 kg [95% CI, -.07 to .04], 20 KKW: -.04 kg [95% CI, -.10 to .02]) was similar (P ≥ .23). Most exercisers (82.6%) compensated (weight loss less than expected). Exercisers who compensated exhibited a 2.5-cm (95% CI, .8 to 4.2) and .23-kg (95% CI, .14 to .31) increase in waist circumference and VAT, respectively, vs those who did not (P < .01). Desire to eat predicted VAT change during exercise (β = .21; P = .03).

CONCLUSION

In the presence of significant weight compensation, exercise at doses recommended for health and weight loss and weight maintenance leads to negligible changes in central adiposity.

Early temperament and physical health in school-age children: Applying a short temperament measure in a population-based cohort

Temperament has drawn considerable attention in the understanding of behavioural problems and psychopathology across developmental stages. However, less of a focus has been placed on the role of temperament in physical aspects of health. We aimed to examine the relations between early temperament traits and physical health in school-age children. This study used longitudinal data of 18,994 children (52.4% boys) born in 2005 from the Taiwan Birth Cohort Study, in which follow-up surveys were conducted via face-to-face interviews with the child's caregiver. Temperament at 5.5 years of age was assessed using a nine-item measure, and two higher-order temperament traits, surgency and regulation, were derived through confirmatory factor analysis. Physical health outcomes at age 8 included caregiver-rated general health status and medically attended injuries. Multiple logistic regression analysis was applied, with the child's birth outcome, early health status or injury history, health behaviours and family socioeconomic status as control variables. The results indicated that higher levels of surgency and regulation, as early temperament traits, significantly predicted lower odds of caregiver-rated poor health in later years. Higher level of regulation was also associated with lower odds of injury risk. Our findings suggest that assessing early temperament traits could be useful for the promotion and management of physical health in young school-age children.

Child temperament and physical activity in young children

BACKGROUND

Children's temperament has been noted to influence their physical activity (PA) levels. Therefore, understanding the influence of temperament during the early years may be helpful for developing appropriate PA habits and tailoring interventions to align with different personality traits.

OBJECTIVE

The purpose of this study was to examine the relationship between child temperament and objectively-measured PA in preschool-aged children.

METHODS

Data were collected as part of the Supporting Physical Activity in the Childcare Environment (SPACE) and SPACE extension studies. Temperament data were collected using the validated Very Short Form of the Children's Behavior Questionnaire, which assessed three dimensions of temperament (i.e., surgency, negative affect and effortful control). Physical activity data were measured during childcare hours over the course of 5 days, using Actical® accelerometers. Total PA was summed, along with light and moderate-to-vigorous PA using age-specific cut-points. Three regression analyses were conducted to evaluate the prediction of PA by the dimensions of temperament.

RESULTS

A total of 399 participants (M_age  = 3.34 years, SD = 0.63) were retained for analyses, wearing an accelerometer an average of 7.21 h/day. Temperament significantly predicted all three PA levels (P < 0.05), with both negative affect and surgency being significantly associated with PA.

CONCLUSION

Surgency is typified by a predisposition towards high activity levels; therefore, it is not surprising that it was the primary predictor of young children's PA. Future research may investigate methods of targeting PA interventions towards children with temperaments that may not predispose them to seeking out increased activity levels.

Initial Weight Change and Long-Term Changes in Weight and Compensation during Supervised Exercise Training

INTRODUCTION

Our primary aim was to investigate the association between initial weight change and longer-term changes in weight and compensation (predicted weight loss-observed weight loss) during exercise. As secondary aims, we investigated if initial weight change was related to change in cardiometabolic risk markers and energy balance modulators.

METHODS

Two 6-month randomized controlled exercise trials conducted in individuals with overweight or obesity were analyzed (study 1, n = 312; study 2, n = 102). In both studies, participants in an exercise condition (4 kcal·kg-1·wk-1 [KKW], 8 KKW, 12 KKW, or 20 KKW) were split into tertiles based on percent weight change from baseline to week 4. Tertiles 1 and 3 exhibited the least and most initial weight loss, respectively. Changes in end points were compared between tertiles.

RESULTS

At month 6, weight loss was lower in tertile 1 than tertile 3 (study 1: -3.6%, 95% confidence interval [CI] = -4.6 to -2.6; study 2: -1.8%, 95% CI = -3.1 to -0.4; P ≤ 0.034). Tertile 1 also showed greater compensation than tertile 3 in study 1 (3.0 kg, 95% CI = 2.2 to 3.9) and study 2 (1.5 kg, 95% CI = 0.3 to 2.6; P ≤ 0.048). Changes in triglycerides and, in study 1, HDL cholesterol were less favorable in tertile 1 versus tertile 3 (P ≤ 0.043); however, changes in other cardiometabolic markers were similar (P ≥ 0.209). In study 2, tertile 1 increased energy intake and exhibited maladaptive changes in eating behaviors relative to tertile 3 (P < 0.050). No between-tertile differences in cumulative exercise energy expenditure and physical activity were evident (P ≥ 0.321).

CONCLUSIONS

Less initial weight loss was associated with longer-term attenuated weight loss and greater compensation during aerobic exercise training. Individuals who display less initial weight loss during exercise may require early interventions to decrease compensation and facilitate weight loss.

Measurement of Motivation States for Physical Activity and Sedentary Behavior: Development and Validation of the CRAVE Scale

Physical activity, and likely the motivation for it, varies throughout the day. The aim of this investigation was to create a short assessment (CRAVE: Cravings for Rest and Volitional Energy Expenditure) to measure motivation states (wants, desires, urges) for physical activity and sedentary behaviors. Five studies were conducted to develop and evaluate the construct validity and reliability of the scale, with 1,035 participants completing the scale a total of 1,697 times. In Study 1, 402 university students completed a questionnaire inquiring about the want or desire to perform behaviors "at the present moment (right now)." Items related to physical activity (e.g., "move my body") and sedentary behaviors (e.g., "do nothing active"). An exploratory structural equation model (ESEM) revealed that 10 items should be retained, loading onto two factors (5 each for Move and Rest). In Study 2, an independent sample (n = 444) confirmed these results and found that Move and Rest desires were associated with stage-of-change for exercise behavior. In Study 3, 127 community-residing participants completed the CRAVE at 6-month intervals over two years- two times each session. Across-session interclass correlations (ICC) for Move (ICC = 0.72-0.95) and Rest (ICC = 0.69-0.88) were higher than when they were measured across 24-months (Move: ICC = 0.53; Rest: ICC = 0.49), indicating wants/desires have state-like qualities. In Study 4, a maximal treadmill test was completed by 21 university students. The CRAVE was completed immediately pre and post. Move desires decreased 26% and Rest increased 74%. Changes in Move and Rest desires were moderately associated with changes in perceived physical fatigue and energy. In Study 5, 41 university students sat quietly during a 50-min lecture. They completed the CRAVE at 3 time points. Move increased 19.6% and Rest decreased 16.7%. Small correlations were detected between move and both perceived energy and tiredness, but not calmness or tension. In conclusion, the CRAVE scale has good psychometric properties. These data also support tenets of the WANT model of motivation states for movement and rest (Stults-Kolehmainen et al., 2020a). Future studies need to explore how desires to move/rest relate to dynamic changes in physical activity and sedentarism.

Effect of different doses of supervised exercise on food intake, metabolism, and non-exercise physical activity: The E-MECHANIC randomized controlled trial

BACKGROUND

Exercise is recommended for weight management, yet exercise produces less weight loss than expected, which is called weight compensation. The mechanisms for weight compensation are unclear.

OBJECTIVE

The aim of this study was to identify the mechanisms responsible for compensation.

METHODS

In a randomized controlled trial conducted at an academic research center, adults (n = 198) with overweight or obesity were randomized for 24 wk to a no-exercise control group or 1 of 2 supervised exercise groups: 8 kcal/kg of body weight/wk (KKW) or 20 KKW. Outcome assessment occurred at weeks 0 and 24. Energy intake, activity, and resting metabolic rate (RMR) were measured with doubly labeled water (DLW; with and without adjustments for change in RMR), armband accelerometers, and indirect calorimetry, respectively. Appetite and compensatory health beliefs were measured by self-report.

RESULTS

A per-protocol analysis included 171 participants (72.5% women; mean ± SD baseline body mass index: 31.5 ± 4.7 kg/m2). Significant (P < 0.01) compensation occurred in the 8 KKW (mean: 1.5 kg; 95% CI: 0.9, 2.2 kg) and 20 KKW (mean: 2.7 kg; 95% CI: 2.0, 3.5 kg) groups, and compensation differed significantly between the exercise groups (P = 0.01). Energy intake by adjusted DLW increased significantly (P < 0.05) in the 8 KKW (mean: 90.7 kcal/d; 95% CI: 35.1, 146.4 kcal/d) and 20 KKW (mean: 123.6 kcal/d; 95% CI: 64.5, 182.7 kcal/d) groups compared with control (mean: -2.3 kcal/d; 95% CI: -58.0, 53.5 kcal/d). Results were similar without DLW adjustment. RMR and physical activity (excluding structured exercise) did not differentially change among the 3 groups. Participants with higher compared with lower compensation reported increased appetite ratings and beliefs that healthy behaviors can compensate for unhealthy behaviors. Furthermore, they increased craving for sweet foods, increased sleep disturbance, and had worsening bodily pain.

CONCLUSIONS

Compensation resulted from increased energy intake and concomitant increases in appetite, which can be treated with dietary or pharmacological interventions. Compensation was not due to activity or metabolic changes. This trial was registered at clinicaltrials.gov as NCT01264406.

Child temperament predicts the adiposity rebound. A 9-year prospective sibling control study

METHODS

We repeatedly examined 25889 siblings within the Norwegian Mother and Child Cohort Study, following them from the mothers' pregnancy through child age 8 years. Information on the children's height and weight was collected by means of health registries and maternal reports. Information on the siblings' temperament was collected by questionnaires completed when they were 1.5, 3, and 5 years old. We examined the associations of temperament at different child ages with the timing of the adiposity rebound among siblings and controls by means of growth curve and multilevel analyses.

RESULTS

Within siblings, high scores on the approach trait of sociability predicted an earlier adiposity rebound and high scores on the avoidance trait of shyness predicted a later adiposity rebound with timing differences ranging between 6 and 16 weeks. Surprisingly, negative emotionality did not predict the adiposity rebound. The associations between temperament and the adiposity rebound increased with increasing child age. The results within controls-comparing siblings with the population, broadly paralleled those within siblings.

CONCLUSIONS

The findings encourage the notion that child temperament functions as an early marker for the adiposity rebound. Future studies may advance our knowledge by including measures of child personality along the taxonomy of the adult Five Personality Factors.

Role of parental and environmental characteristics in toddlers' physical activity and screen time: Bayesian analysis of structural equation models

Background

Guided by the Socialization Model of Child Behavior (SMCB), this cross-sectional study examined direct and indirect associations of parental cognitions and behavior, the home and neighborhood environment, and toddlers’ personal attributes with toddlers’ physical activity and screen time.

Methods

Participants included 193 toddlers (1.6 ± 0.2 years) from the Parents’ Role in Establishing healthy Physical activity and Sedentary behavior habits (PREPS) project. Toddlers’ screen time and personal attributes, physical activity- or screen time-specific parental cognitions and behaviors, and the home and neighborhood environment were measured via parental-report using the PREPS questionnaire. Accelerometry-measured physical activity was available in 123 toddlers. Bayesian estimation in structural equation modeling (SEM) using the Markov Chain Monte Carlo algorithm was performed to test an SMCB hypothesized model. Covariates included toddlers’ age, sex, race/ethnicity, main type of childcare, and family household income.

Results

In the SMCB hypothesized screen time model, higher parental barrier self-efficacy for limiting toddlers’ screen time was associated with higher parental screen time limiting practices (β = 0.451), while higher parental negative outcome expectations for limiting toddlers’ screen time was associated with lower parental screen time limiting practices (β = − 0.147). In turn, higher parental screen time limiting practices was associated with lower screen time among toddlers (β = − 0.179). Parental modeling of higher screen time was associated with higher screen time among toddlers directly (β = 0.212) and indirectly through the home environment. Specifically, higher screen time among parents was associated with having at least one electronic device in toddlers’ bedrooms (β = 0.146) and, in turn, having electronics in the bedroom, compared to none, was associated with higher screen time among toddlers (β = 0.250). Neighborhood safety was not associated with toddlers’ screen time in the SEM analysis. No significant correlations were observed between the SMCB variables and toddlers’ physical activity; thus, no further analyses were performed for physical activity.

Conclusions

Parents and their interactions with the home environment may play an important role in shaping toddlers’ screen time. Findings can inform family-based interventions aiming to minimize toddlers’ screen time. Future research is needed to identify correlates of toddlers’ physical activity.

Does Childhood Temperamental Activity Predict Physical Activity and Sedentary Behavior over a 30-Year Period? Evidence from the Young Finns Study

PURPOSE

We examined associations between childhood temperamental activity, physical activity (PA), and television (TV) viewing over a 30-year period.

METHOD

The participants (1220 boys and 1237 girls) were aged 3, 6, 9, and 12 years in 1980 and were followed until 2011. Temperamental activity was evaluated by participants' mothers at baseline. The PA was assessed based on maternal ratings of the child from ages 3 to 6 and via self-report age from the age of 9 across all measurements. TV viewing was assessed using self-reports taken from 2001 to 2011. The associations between temperamental activity and the level and change of PA and TV viewing were determined using linear growth modeling stratified by gender and age group.

RESULTS

High temperamental activity assessed from ages 9 to 12 was associated with high levels of childhood PA in both genders, but with a steeper decline in PA levels during the first 9 years of follow-up in boys. High temperamental activity assessed from ages 3 to 6 was associated with the decline of PA from childhood to youth in girls. High childhood temperamental activity was associated with decreased levels of PA in adulthood in men, but not in women. The associations between childhood temperamental activity and TV viewing during adulthood seemed to be positive but not consistently significant in all age and gender groups.

CONCLUSION

High temperamental activity may contribute to the development of a physically inactive lifestyle. More evidence is needed with regard to gender differences among participants in similar study settings.

Temperament and Physical Activity in Childhood

BACKGROUND

Temperament activity level can serve as a proxy for nondeliberate activity and an important part of overall energy expenditure. However, little is known about any association between temperament activity level and children's levels of moderate- to vigorous-intensity physical activity. We examined whether temperament activity level in young children is associated with moderate- to vigorous-intensity physical activity later in childhood and midadolescence. We also assessed if parenting behaviors moderate any association.

METHODS

Data were obtained from 799 children and their mothers involved in the National Institute of Child Health and Human Development Study of Early Child Care and Youth Development. Growth curve analyses were used to examine the relationships over time, controlling for child and parent characteristics.

RESULTS

High temperament activity level at age 4.5 was associated with higher moderate- to vigorous-intensity physical activity at age 9 (β = 5.15; SE =2.47; P < .001). The association became no longer significant after 10.2 years of age. The association was moderated by parental support for physical activity (β = -2.56; SE = 1.01; P = .01).

CONCLUSIONS

Low temperament activity level in early childhood was a risk factor for low physical activity in later childhood and adolescence. Parental support for physical activity may be beneficial for children whose temperament activity level is low.

Childhood temperament predictors of adolescent physical activity

Background

Physical inactivity is a leading cause of mortality worldwide. Many patterns of physical activity involvement are established early in life. To date, the role of easily identifiable early-life individual predictors of PA, such as childhood temperament, remains relatively unexplored. Here, we tested whether childhood temperamental activity level, high intensity pleasure, low intensity pleasure, and surgency predicted engagement in physical activity (PA) patterns 11 years later in adolescence.

Methods

Data came from a longitudinal community study (N = 206 participants, 53% females, 70% Caucasian). Parents reported their children’s temperamental characteristics using the Child Behavior Questionnaire (CBQ) when children were 4 & 5 years old. Approximately 11 years later, adolescents completed self-reports of PA using the Godin Leisure Time Exercise Questionnaire and the Youth Risk Behavior Survey. Ordered logistic regression, ordinary least squares linear regression, and Zero-inflated Poisson regression models were used to predict adolescent PA from childhood temperament. Race, socioeconomic status, and adolescent body mass index were used as covariates.

Results

Males with greater childhood temperamental activity level engaged in greater adolescent PA volume (B = .42, SE = .13) and a 1 SD difference in childhood temperamental activity level predicted 29.7% more strenuous adolescent PA per week. Males’ high intensity pleasure predicted higher adolescent PA volume (B = .28, SE = .12). Males’ surgency positively predicted more frequent PA activity (B = .47, SE = .23, OR = 1.61, 95% CI: 1.02, 2.54) and PA volume (B = .31, SE = .12). No predictions from females’ childhood temperament to later PA engagement were identified.

Conclusions

Childhood temperament may influence the formation of later PA habits, particularly in males. Boys with high temperamental activity level, high intensity pleasure, and surgency may directly seek out pastimes that involve PA. Indirectly, temperament may also influence caregivers’ perceptions of optimal activity choices for children. Understanding how temperament influences the development of PA patterns has the potential to inform efforts aimed at promoting long-term PA engagement and physical health.

Diet-induced obesity resistance of adult female mice selectively bred for increased wheel-running behavior is reversed by single perinatal exposure to a high-energy diet

Female mice from independently bred lines previously selected over 50 generations for increased voluntary wheel-running behavior (S1, S2) resist high energy (HE) diet-induced obesity (DIO) at adulthood, even without actual access to running wheels, as opposed to randomly bred controls (CON). We investigated whether adult S mice without wheels remain DIO-resistant when exposed - via the mother - to the HE diet during their perinatal stage (from 2 weeks prior to conception until weaning on post-natal day 21). While S1 and S2 females subjected to HE diet either perinatally or from weaning onwards (post-weaning) resisted increased adiposity at adulthood (as opposed to CON females), they lost this resistance when challenged with HE diet during these periods combined over one single cycle of breeding. When allowed one-week access to wheels (at week 6-8 and at 10 months), however, tendency for increased wheel-running behavior of S mice was unaltered. Thus, the trait for increased wheel-running behavior remained intact following combined perinatal and post-weaning HE exposure, but apparently this did not block HE-induced weight gain. At weaning, perinatal HE diet increased adiposity in all lines, but this was only associated with hyperleptinemia in S lines irrespective of gender. Because leptin has multiple developmental effects at adolescence, we argue that a trait for increased physical activity may advance maturation in times of plenty. This would be adaptive in nature where episodes of increased nutrient availability should be exploited maximally. Associated disturbances in glucose homeostasis and related co-morbidities at adulthood are probably pleiotropic side effects.

Temperament and Objectively Measured Physical Activity and Sedentary Time among Canadian Preschoolers

This study sought to assess the influence of preschoolers' temperament on their objectively measured physical activity and sedentary time. Actical™ accelerometers were used to measure preschoolers' from London, Canada's (n = 216; 2.5–5 years) physical activity and sedentary levels during childcare hours (5 consecutive days; 15 s epoch). The Child Temperament Questionnaire (CTQ) was used to assess child temperament via parent/guardian report. The six subscales of the CTQ (i.e., reaction to food, soothability, attention span, activity, sociability, and emotionality) were correlated with Actical data (i.e., sedentary time, moderate-to-vigorous physical activity, and total physical activity). The five items of the activity subscale were correlated with these three measures of sedentary time and physical activity. Pearson product–moment correlation coefficients were employed for both sets of analyses. Of the correlations examined, few had an absolute value greater than 0.10, and none were statistically significant after taking multiple comparison bias into account. The results of this work might provide additional indirect support for the conclusion that the childcare environment should be a primary focus with regard to the promotion of increased physical activity and decreased sedentary time among preschoolers. Additional research is required to confirm the relationship between preschoolers' temperament and levels of physical activity and sedentary time.

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This is the first study to explore preschoolers' temperament and physical activity.

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Temperament was not predictive of preschoolers' physical activity or sedentary time.

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The lack of association could be a result of the tool used (e.g., CTQ).

Examination of mechanisms (E-MECHANIC) of exercise-induced weight compensation: study protocol for a randomized controlled trial

BACKGROUND

Weight loss induced only by exercise is frequently less than expected, possibly because of compensatory changes in energy intake and/or energy expenditure. The purpose of the Examination of Mechanisms (E-MECHANIC) of Exercise-Induced Weight Compensation trial is to examine whether increased energy intake and/or reduced spontaneous activity or energy expenditure (outside of structured exercise) account for the less than expected, exercise-associated weight loss.

METHODS/DESIGN

E-MECHANIC is a three-arm, 6-month randomized (1:1:1) controlled trial. The two intervention arms are exercise doses that reflect current recommendations for (1) general health (8 kcal/kg body weight per week (8 KKW), about 900 kcal/wk) and (2) weight loss (20 KKW, about 2,250 kcal/wk). The third arm, a nonexercise control group, will receive health information only. The sample will include a combined total of 198sedentary, overweight or obese (body mass index: ≥25 kg/m² to ≤45 kg/m²) men and women ages 18 to 65 years. The exercise dose will be supervised and tightly controlled in an exercise training laboratory. The primary outcome variables are energy intake, which will be measured using doubly labeled water (adjusted for change in energy stores) and laboratory-based food intake tests, and the discrepancy between expected weight loss and observed weight loss. Secondary outcomes include changes in resting metabolic rate (adjusted for change in body mass), activity levels (excluding structured exercise) and body composition. In an effort to guide the development of future interventions, the participants will be behaviorally phenotyped and defined as those who do compensate (that is, fail to lose the amount of weight expected) or do not compensate (that is, lose the amount of weight expected or more).

DISCUSSION

In this study, we will attempt to identify underlying mechanisms to explain why exercise elicits less weight loss than expected. This information will guide the development of interventions to increase exercise-induced weight loss and maximize weight loss retention and related health benefits.

TRIAL REGISTRATION

ClinicalTrials.gov ID: NCT01264406 (registration date: 20 December 2010).

Learning Environments' Activity Potential for Preschoolers (LEAPP): Study Rationale and Design

BACKGROUND

The purpose of this paper is to provide an overview of the study protocol for the Learning Environments' Activity Potential for Preschoolers (LEAPP) study, the goal of which is to describe the activity levels of preschoolers attending various early learning venues and explore which attributes of these facilities (e.g. curriculum, policies, equipment, etc.) support activity participation.

DESIGN AND METHODS

This cross-sectional study aimed to recruit approximately 30 early learning environments requesting participation from preschoolers aged 2.5-5 years. Data collection included: Actical accelerometers (MiniMitter, Oregon, USA) to measure the activity levels of children for five consecutive days (15-second epoch length) while in care; the Environment and Policy Assessment and Observation tool to explore the early learning environment's impact on activity; anthropometric data; the Child Temperament Questionnaire to assess the influence of preschoolers' temperament on physical activity; and demographic information from parents/guardians and early learning staff. ANOVA and linear regression analyses will be conducted to assess variances in activity levels among preschoolers attending different early learning types and to explore the impact of early learning environments on their activity levels. Independent sample t-tests will be used to examine differences in activity levels based on sex and weight status.

EXPECTED IMPACT OF THE STUDY FOR PUBLIC HEALTH

This research will provide the first Canadian data to address environmental influences on preschoolers' activity levels in differing early learning environments. Additionally, this work will highlight the extent to which activity levels vary among preschoolers enrolled in full-day kindergarten, centre-, and home-based childcare. Significance for public healthThis study represents the first examination of the differences in physical activity levels among preschoolers attending various early learning environments. As such, it is important that the methodology undertaken be shared in the event that other researchers doing comparable work want to adopt a similar approach. Results of this research may inform the work of health promotion, public health, and early learning stakeholders. Specifically this work may impact early learning curricula, policies, and practices in service of helping Canada's preschool cohort become sufficiently physically active.

Disparate effects of feeding on core body and adipose tissue temperatures in animals selectively bred for Nervous or Calm temperament

In addition to homeostatic regulation of body mass, nonhomeostatic factors impact on energy balance. Herein we describe effects of temperament on adipose and core body temperatures in sheep. Animals were genetically selected for Nervous or Calm traits. We characterized the effects of 1) high- and low-energy intake and maintenance feeding, 2) meal anticipation, and 3) adrenocorticotropin challenge on core body and adipose temperatures. Temperature measurements (5 min) were made using a thermistor inserted into the carotid artery (core body) and a probe in the retroperitoneal fat. An imposed feeding window was used to establish postprandial elevations in temperature. Fat tissue was taken from retroperitoneal and subcutaneous regions for real-time PCR analyses. We demonstrate that innate differences in temperament impact on adipose and core body temperatures in response to various dietary and evocative stimuli. In response to homeostatic cues (low-energy intake and maintenance feeding) core body temperature tended to be higher in Calm compared with Nervous animals. In contrast, in response to nonhomeostatic cues, Nervous animals had higher anticipatory thermogenic responses than Calm animals. Expression of uncoupling protein (UCP)-1 and -2 mRNA were higher in retroperitoneal tissue than in subcutaneous tissue, but UCP3 and leptin mRNA levels were similar at both sites; expression of these genes was similar in Nervous and Calm animals. There were no differences in stress responsiveness. We conclude that temperament differentially influences adipose thermogenesis and the regulation of core body temperature in responses to both homeostatic and nonhomeostatic stimuli.

Infant temperament and eating style predict change in standardized weight status and obesity risk at 6 years of age

OBJECTIVE

Little research has addressed the relationships among infant temperament, eating styles and obesity risk. To address this gap, we tested whether infant temperament and eating patterns at the age of 1 year are associated with a greater increase in standardized weight status, and greater obesity risk at 6 years of age.

DESIGN

A secondary, prospective analysis of the Colorado Adoption Study was conducted. The main predictor variables were infant temperament (that is, emotionality, activity, attention span-persistence, reaction to food and soothability) and eating domains (that is, reactivity to food, predictable appetite and distractability at mealtime) at the age of 1 year, along with the body mass index (BMI) of biological mothers. The outcome measures were child weight and height (length) assessed at ages 1 through 6 years, from which weight-for-length and BMI were computed along with the standardized indexes (z-scores) and percentiles. Overweight/obesity status was computed at each year as well.

PARTICIPANTS

A primarily White sample of 262 boys and 225 girls, assessed at ages 1 through 6 years, along with their mothers.

RESULTS

Among boys, greater attention span-persistence was associated with reduced standardized weight status gain (β=-0.15, P<0.05) and reduced obesity risk (odds ratio (OR)=0.46, P=0.06). Among girls, greater soothability and negative reaction to food were associated with greater standardized weight status gain (β=0.19, P<0.01; and β=0.16, P<0.05, respectively) and increased obesity risk (OR=3.72, P=0.03; and OR=2.81, P=0.08, respectively). Biological mothers' obesity status predicted obesity risk in boys (OR=3.07, P=0.01) and girls (OR=5.94, P=0.03).

CONCLUSIONS

Male infants with less attention span, and female infants with greater soothability or a more negative food reaction, showed greater increases in standardized weight and were more likely to be overweight/obese at the age of 6 years. The role of infant temperament in pediatric obesity onset warrants greater research.

Environmental influences on children's physical activity: quantitative estimates using a twin design

BACKGROUND

Twin studies offer a 'natural experiment' that can estimate the magnitude of environmental and genetic effects on a target phenotype. We hypothesised that fidgetiness and enjoyment of activity would be heritable but that objectively-measured daily activity would show a strong shared environmental effect.

METHODOLOGY/PRINCIPAL FINDINGS

In a sample of 9-12 year-old same-sex twin pairs (234 individuals; 57 MZ, 60 DZ pairs) we assessed three dimensions of physical activity: i) objectively-measured physical activity using accelerometry, ii) 'fidgetiness' using a standard psychometric scale, and iii) enjoyment of physical activity from both parent ratings and children's self-reports. Shared environment effects explained the majority (73%) of the variance in objectively-measured total physical activity (95% confidence intervals (CI): 0.63-0.81) with a smaller unshared environmental effect (27%; CI: 0.19-0.37) and no significant genetic effect. In contrast, fidgetiness was primarily under genetic control, with additive genetic effects explaining 75% (CI: 62-84%) of the variance, as was parent's report of children's enjoyment of low 74% (CI: 61-82%), medium 80% (CI: 71-86%), and high impact activity (85%; CI: 78-90%), and children's expressed activity preferences (60%, CI: 42-72%).

CONCLUSIONS

Consistent with our hypothesis, the shared environment was the dominant influence on children's day-to-day activity levels. This finding gives a strong impetus to research into the specific environmental characteristics influencing children's activity, and supports the value of interventions focused on home or school environments.

Injury risk from popular childhood physical activities: results from an Australian primary school cohort

BACKGROUND

Children engage in various physical activities that pose different injury risks. However, the lack of adequate data on exposure has meant that these risks have not been quantified or compared in young children aged 5-12 years.

OBJECTIVES

To measure exposure to popular activities among Australian primary school children and to quantify the associated injury risks.

METHOD

The Childhood Injury Prevention Study prospectively followed up a cohort of randomly selected Australian primary and preschool children aged 5-12 years. Time (min) engaged in various physical activities was measured using a parent-completed 7-day diary. All injuries over 12 months were reported to the study. All data on exposure and injuries were coded using the International classification of external causes of injury. Injury rates per 1000 h of exposure were calculated for the most popular activities.

RESULTS

Complete diaries and data on injuries were available for 744 children. Over 12 months, 314 injuries relating to physical activity outside of school were reported. The highest injury risks per exposure time occurred for tackle-style football (2.18/1000 h), wheeled activities (1.72/1000 h) and tennis (1.19/1000 h). Overall, boys were injured more often than girls; however, the differences were non-significant or reversed for some activities including soccer, trampolining and team ball sports.

CONCLUSION

Although the overall injury rate was low in this prospective cohort, the safety of some popular childhood activities can be improved so that the benefits may be enjoyed with fewer negative consequences.

Childhood Obesity: The Infancy Connection

The prevalence of overweight has risen to 19% in children aged 6 to 11 years and 17% in adolescents aged 12 to 19 years. This paper examines gestational and infancy factors that influence the risk of overweight in childhood. Important factors to eliminate the infancy connection to childhood obesity include the following: (a) maternal lifestyle patterns, (b) infant feeding transitions, and (c) environmental factors. Prevention efforts need to focus on practice, research, and public policy.

Compliance with the Australian national physical activity guidelines for children: relationship to overweight status

Childhood obesity incidence has increased substantially and it has been argued that decreasing physical activity levels, coinciding with an increase in sedentary behaviours, are responsible. Australian guidelines were published in 2004, recommending that children participate in a minimum of 60 min of physical activity daily and spend no more than 2h a day using electronic media for entertainment. We aimed to compare compliance with these guidelines amongst children of differing weight status. The Childhood Injury Prevention Study (CHIPS) collected data from a randomly selected sample of Brisbane primary and preschool children aged 5-12 years. The following data were available for 518 participants: age, gender, measured height and weight and estimated time per week from a parent-completed 7 days diary in physical activity out of school and sedentary leisure activities including television viewing and computer use. Using age standardised body mass index estimates, approximately 20% of the cohort were overweight. Non-compliance with guidelines was 14.7% for out of school physical activity participation, and 30.9% for excess electronic media entertainment use. There was a 63% increase in the odds of overweight status amongst children who were non-compliant with the electronic entertainment recommendations than those who were compliant (adjusted odds ratio=1.63; 95% CI=1.05-2.54). Female gender and school level socioeconomic category were also independently associated with overweight status. Non-compliance with the minimal physical activity guideline increased the odds of being overweight by 28%, however this difference was not statistically significant. One in seven children from the Greater Brisbane area are at risk for being insufficiently active whilst a third overuse electronic media. Given that overuse of electronic entertainment was positively associated with childhood obesity, these children should be the target of public health campaigns to promote alternative leisure time activities.

Physical activity and sedentary behavior: a review of longitudinal studies of weight and adiposity in youth

AIM

To review the published prospective observational studies of the relationship of physical activity and sedentary behavior with the development of overweight and adiposity, with an emphasis on methodologic issues.

METHODS

Sample size, population studied, length of follow-up, assessment of exposure (physical activity, inactivity, or sedentary behavior), assessment of outcome (relative weight, overweight, % body fatness, adiposity), statistical approach, and main findings were extracted, summarized, and key methodological issues highlighted.

RESULTS

In total, 17 studies of physical activity and 15 studies of inactivity/sedentary behavior were identified; as these were not mutually exclusive, 20 unique studies were reviewed. Results were mixed, with most studies showing an inverse association of physical activity with weight or fatness outcomes and/or a direct association of inactivity/sedentary behavior with weight or fatness outcomes. The effects identified were generally of small magnitude. Imprecise measurement of activity exposures likely weakens the observed relationships. Most studies used a pre-post design and had limited duration of follow-up (< or = 2y). Studies with longer and more frequent follow-up did not always use the most advantageous statistical approach.

CONCLUSIONS

On balance, the available evidence from prospective observational studies suggests that increased physical activity and decreased sedentary behavior are protective against relative weight and fatness gains over childhood and adolescence. In addition to improved measurement methods, longer and more frequent follow-up as well as truly longitudinal analysis methods would help establish these important prevention and intervention targets, and identify subgroups or development periods where interventions would likely be effective.

Child temperament does not predict adolescent body composition in girls

OBJECTIVES

Our previous cross-sectional analysis of MIT Growth and Development (MIT) Study girls showed that activity temperament, as assessed by a nine-item temperament questionnaire, was related to body composition and nonresting energy expenditure (NREE). In girls with lower levels of physical activity, having a high activity temperament was associated with a higher NREE. Percentage body fat was lower in girls with high vs low activity temperament. Based on these results, we hypothesized that, especially in girls with declining levels of physical activity over adolescence, high activity temperament in childhood would be protective against increased adiposity during adolescence. We tested this hypothesis with longitudinal data from the MIT study.

DESIGN, SETTING, AND PARTICIPANTS

A total of 196 nonobese premenarcheal girls 8-12 y old were enrolled between 1990 and 1993. Girls were followed until 4 y postmenarche; average duration of follow-up was 7 y.

MEASURES

Activity temperament was assessed at baseline by the girls' mothers with questions modified from those developed by Thomas and Chess that tapped predilection for movement. Temperament, the stylistic component of behavior, is considered relatively stable within an individual. Body composition was assessed by total body water at baseline and study completion (4 y postmenarche), and by bioelectrical impedance (BIA) annually. Physical activity was assessed annually by questionnaire, and by activity diary at baseline only.

RESULTS

Child activity temperament was not associated with percentage body fat at 4 y postmenarche in multivariate regression models controlling for baseline percentage body fat, physical activity, parental obesity status, age at menarche, age at baseline, and race-ethnicity. Body composition of girls with low and high activity temperaments who reported declining levels of physical activity over adolescence was not statistically significantly different at study completion. In longitudinal models of percentage body fat by BIA, high activity temperament was not associated with lower adiposity.

CONCLUSION

Although high activity temperament was associated cross-sectionally with lower percentage body fat and higher NREE, we did not find evidence to support our hypothesis that high child activity temperament would be protective for increased adiposity prospectively in our cohort of girls followed over the adolescent period.