Intensity and seasonality of physical activity of children during school recess

This study aimed to quantify the intensity of physical activity (PA) of children during school recess (RE), compare the AF gender and seasonal influences. The sample consisted of 30 girls (11.2 ± 1.3 years) and 20 boys (11.3 ± 0.8 years). Heart rate was monitored for three consecutive REs in winter (INV) and spring (PRI) with intensity of the activity being classified as low, moderate and vigorous. Descriptive statistics were used for general data, t test for independent samples for differences between the sexes, paired t test for seasonality. Differences were found between INV and PRI temperatures. Girls had a significant reduction in the AF INV to PRI, which was not observed among boys. The RE represented a small contribution to daily recommendations of AF.

Effect of physical activity and other stressors on appetite: Overcoming underconsumption of military operational rations revisited.

Recognizing the importance of good nutrition for physical and mental status, the Department of Defense asked the Institute of Medicine to guide the design of the nutritional composition of a ration for soldiers on short-term, high-stress missions. Nutrient Composition of Rations for Short-Term, High-Intensity Combat Operations considers military performance, health concerns, food intake, energy expenditure, physical exercise, and food technology issues. The success of military operations depends to a large extent on the physical and mental status of the individuals involved.

Fitness and fatness in childhood obesity : implications of physical activity

Overweight and obesity are a significant cause of poor health worldwide, particularly in conjunction with low levels of physical activity (PA). PA is health-protective and essential for the physical growth and development of children, promoting physical and psychological health while simultaneously increasing the probability of remaining active as an adult. However, many obese children and adolescents have a unique set of physiological, biomechanical, and neuromuscular barriers to PA that they must overcome. It is essential to understand the influence of these barriers on an obese child's motivation in order to exercise and tailor exercise programs to the special needs of this population. Chapter Outline • Introduction • Defining Physical Activity, Exercise, and Physical Fitness • Physical Activity, Physical Fitness, And Motor Competence In Obese Children • Physical Activity and Obesity in Children • Physical Fitness in Obese Children • Balance and Gait in Obese Children • Motor Competence in Obese Children • Physical Activity Guidelines for Obese Children • Clinical Assessment of the Obese Child • Physical Activity Characteristics: Mode • Physical Activity Characteristics: Intensity • Physical Activity Characteristics: Frequency • Physical Activity Characteristics: Duration • Conclusion

Practical physical activity measurement in youth : a review of contemporary approaches

Background: The accurate evaluation of physical activity levels amongst youth is critical for quantifying physical activity behaviors and evaluating the effect of physical activity interventions. The purpose of this review is to evaluate contemporary approaches to physical activity evaluation amongst youth. Data sources: The literature from a range of sources was reviewed and synthesized to provide an overview of contemporary approaches for measuring youth physical activity. Results: Five broad categories are described: self-report, instrumental movement detection, biological approaches, direct observation, and combined methods. Emerging technologies and priorities for future research are also identified. Conclusions: There will always be a trade-off between accuracy and available resources when choosing the best approach for measuring physical activity amongst youth. Unfortunately, cost and logistical challenges may prohibit the use of "gold standard" physical activity measurement approaches such as doubly labelled water. Other objective methods such as heart rate monitoring, accelerometry, pedometry, indirect calorimetry, or a combination of measures have the potential to better capture the duration and intensity of physical activity, while self-reported measures are useful for capturing the type and context of activity.

Calibration and evaluation of an objective measure of physical activity in pre-school children

Background The purposes of this study were 1) to establish accelerometer count cutoffs to categorize activity intensity of 3 to 5-y old-children and 2) to evaluate the accelerometer as a measure of children’s physical activity in preschool settings. Methods While wearing an ActiGraph accelerometer, 16 preschool children performed five, 3-min structured activities. Receiver Operating Characteristic (ROC) curve analyses identified count cutoffs for four physical activity intensities. In 9 preschools, 281 children wore an ActiGraph during observations performed by three trained observers (interobserver reli-ability = 0.91 to 0.98). Results Separate count cutoffs for 3, 4, and 5-y olds were established. Sensitivity and specificity for the count cutoffs ranged from 86.7% to 100.0% and 66.7% to 100.0%, respectively. ActiGraph counts/15 s were different among all activities (P < 0.05) except the two sitting activities. Correlations between observed and ActiGraph intensity categorizations at the preschools ranged from 0.46 to 0.70 (P < 0.001). Conclusions The ActiGraph count cutoffs established and validated in this study can be used to objectively categorize the time that preschool-age children spend in different physical activity intensity levels.

Correlates of physical activity behavior in rural youth

The purpose of this study was to identify correlates of physical activity behavior in a sample of rural, predominantly African American youth. Three hundred sixty-one fifth-grade students from two rural counties in South Carolina (69% African American, median age = II years) completed a questionnaire designed to measure beliefs and social influences regarding physical activity, physical activity self-efficacy, perceived physical activity habits of family members and friends, and access to exercise and fitness equipment at home. After school physical activity and television watching were assessed using the Previous Day Physical Activity Recall (PDPAR). Students were classified as physically active according to a moderate physical activity standard: two or more 30-min blocks at an intensity of 3 METs (metabolic equivalents) or greater, and a vigorous physical activity standard: one or more 30-min blocks at an intensity of 6 METs or greater According to the moderate physical activity standard, 34.9% of students were classified as low-active. Multivariate analysis revealed age, gender television watching, and exercise equipment at home to be significant correlates of low activity status. According to the vigorous physical activity standard, 32.1 % of the students were classified as low-active. Multivariate analysis revealed age, gender television watching, and self-efficacy with respect to seeking support for physical activity to be significant correlates of low activity status. In summary, gender and the amount of television watching were found to be the most important correlates of physical activity in rural, predominantly African American youth.

Analysis of physical activity in emmetropic and myopic university students during semester and holiday periods: A pilot study

Background Previous studies (mostly questionnaire-based in children) suggest that outdoor activity is protective against myopia. There are few studies on young adults investigating both the impact of simply being outdoors versus performing physical activity. The aim was to study the relationship between the refractive error of young adults and their physical activity patterns. Methods Twenty-seven university students, aged 18 to 25 years, wore a pedometer (Omron HJ720ITE) for seven days both during the semester and holiday periods. They simultaneously recorded the type of activity performed, its duration, the number of steps taken (from the pedometer) and their location (indoors/outdoors) in a logbook. Mean spherical refractive error was used to divide participants into three groups (emmetropes: +1.00 to -0.50 D, low myopes: -0.62 to -3.00 D, higher myopes: -3.12 D or greater myopia). Results There were no significant differences between the refractive groups during the semester or holiday periods; the average daily times spent outdoors, the duration of physical activity, the ratio of physical activity performed outdoors to indoors and amount of near work performed were similar. The peak exercise intensity was similar across all groups: approximately 100 steps perminute, a brisk walk. Up to one-third of all physical activity was performed outdoors. There were some significant differences in activities performed during semester and holiday times. For example, lowmyopes spent significantly less time outside (49 ± 47 versus 74 ± 41 minutes, p = 0.005) and performed less physical activity (6,388 ± 1,747 versus 6,779 ± 2,746 steps per day; p = 0.03) during the holidays compared to during semester. Conclusions The fact that all groups had similar low exercise intensity butmany were notmyopic suggests that physical activity levels are not critical. There were differences in the activity patterns of lowmyopes during semester and holiday periods. This study highlights the need for a larger longitudinal-based study with particular emphasis on how discretionary time is spent.

Exploring metrics to express energy expenditure of physical activity in youth

Background Several approaches have been used to express energy expenditure in youth, but no consensus exists as to which best normalizes data for the wide range of ages and body sizes across a range of physical activities. This study examined several common metrics for expressing energy expenditure to determine whether one metric can be used for all healthy children. Such a metric could improve our ability to further advance the Compendium of Physical Activities for Youth. Methods A secondary analysis of oxygen uptake (VO2) data obtained from five sites was completed, that included 947 children ages 5 to 18 years, who engaged in 14 different activities. Resting metabolic rate (RMR) was computed based on Schofield Equations [Hum Nutr Clin Nut. 39(Suppl 1), 1985]. Absolute oxygen uptake (ml.min-1), oxygen uptake per kilogram body mass (VO2 in ml.kg-1.min-1), net oxygen uptake (VO2 – resting metabolic rate), allometric scaled oxygen uptake (VO2 in ml.kg-0.75.min-1) and YOUTH-MET (VO2.[resting VO2] -1) were calculated. These metrics were regressed with age, sex, height, and body mass. Results Net and allometric-scaled VO2, and YOUTH-MET were least associated with age, sex and physical characteristics. For moderate-to-vigorous intensity activities, allometric scaling was least related to age and sex. For sedentary and low-intensity activities, YOUTH-MET was least related to age and sex. Conclusions No energy expenditure metric completely eliminated the influence of age, physical characteristics, and sex. The Adult MET consistently overestimated EE. YOUTH-MET was better for expressing energy expenditure for sedentary and light activities, whereas allometric scaling was better for moderate and vigorous intensity activities. From a practical perspective, The YOUTH-MET may be the more feasible metric for improving of the Compendium of Physical Activities for Youth.

Reliability and validity of objective measures of physical activity in youth with cerebral palsy who are ambulatory

BACKGROUND Physical therapy for youth with cerebral palsy (CP) who are ambulatory includes interventions to increase functional mobility and participation in physical activity (PA). Thus, reliable and valid measures are needed to document PA in youth with CP. OBJECTIVE The purpose of this study was to evaluate the inter-instrument reliability and concurrent validity of 3 accelerometer-based motion sensors with indirect calorimetry as the criterion for measuring PA intensity in youth with CP. METHODS Fifty-seven youth with CP (mean age=12.5 years, SD=3.3; 51% female; 49.1% with spastic hemiplegia) participated. Inclusion criteria were: aged 6 to 20 years, ambulatory, Gross Motor Function Classification System (GMFCS) levels I through III, able to follow directions, and able to complete the full PA protocol. Protocol activities included standardized activity trials with increasing PA intensity (resting, writing, household chores, active video games, and walking at 3 self-selected speeds), as measured by weight-relative oxygen uptake (in mL/kg/min). During each trial, participants wore bilateral accelerometers on the upper arms, waist/hip, and ankle and a portable indirect calorimeter. Intraclass coefficient correlations (ICCs) were calculated to evaluate inter-instrument reliability (left-to-right accelerometer placement). Spearman correlations were used to examine concurrent validity between accelerometer output (activity and step counts) and indirect calorimetry. Friedman analyses of variance with post hoc pair-wise analyses were conducted to examine the validity of accelerometers to discriminate PA intensity across activity trials. RESULTS All accelerometers exhibited excellent inter-instrument reliability (ICC=.94-.99) and good concurrent validity (rho=.70-.85). All accelerometers discriminated PA intensity across most activity trials. LIMITATIONS This PA protocol consisted of controlled activity trials. CONCLUSIONS Accelerometers provide valid and reliable measures of PA intensity among youth with CP.

What works elsewhere? A review of physical activity intervention studies

Obesity and type 2 diabetes mellitus (T2D) have reached epidemic proportions in many parts of the world with numbers projected to rise dramatically in coming decades (Wang and Lobstein, 2006; Zaninotto et al., 2006). In Australia, and consistent with much of the developed world, the problem has been described as a ‘juggernaut’ that is out of control (Zimmet and James, 2007). Unfortunately the burgeoning problem of non-communicable diseases, including obesity and T2D, is also impacting developing nations as populations are undergoing a nutrition transition (Caballero, 2005). The increased prevalence of overweight and obesity in children, adolescents and adults in both the developed and developing world is consistent with reductions in all forms of physical activity (Brownson et al., 2005). This brief paper provides an overview of the importance of physical activity and an outline of physical activity intervention studies with particular reference to the growing years. As many interventions studies involving physical activity have been undertaken in the context of childhood obesity prevention (Lobstein et al., 2004), and an increasing proportion of the childhood population is overweight or obese, this is a major focus of discussion.

The contribution of physical activity and sedentary behaviours to the growth and development of children and adolescents : implications for overweight and obesity

The obesity epidemic is a global trend and is of particular concern in children. Recent reports have highlighted the severity of obesity in children by suggesting: “today's generation of children will be the first for over a century for whom life expectancy falls.” This review assesses the evidence that identifies the important role of physical activity in the growth, development and physical health of young people, owing to its numerous physical and psychological health benefits. Key issues, such as “does a sedentary lifestyle automatically lead to obesity” and “are levels of physical activity in today's children less than physical activity levels in children from previous generations?”, are also discussed. Today's environment enforces an inactive lifestyle that is likely to contribute to a positive energy balance and childhood obesity. Whether a child or adolescent, the evidence is conclusive that physical activity is conducive to a healthy lifestyle and prevention of disease. Habitual physical activity established during the early years may provide the greatest likelihood of impact on mortality and longevity. It is evident that environmental factors need to change if physical activity strategies are to have a significant impact on increasing habitual physical activity levels in children and adolescents. There is also a need for more evidence-based physical activity guidelines for children of all ages. Efforts should be concentrated on facilitating an active lifestyle for children in an attempt to put a stop to the increasing prevalence of obese children