Abstract: PURPOSE: This study explored the influence of modernity on the physical activity behaviors (e.g., intensity and timing) of children. METHODS: Children aged 8-13 yr living a traditional lifestyle (Old Order Amish [OOA], n = 68; Old Order Mennonite [OOM], n = 120) were compared with children living a contemporary lifestyle (rural Saskatchewan [RSK], n = 132; urban Saskatchewan [USK], n = 93). Physical activity was objectively assessed for seven consecutive days using Actigraph 7164 accelerometers. Custom software was used to reduce the raw accelerometer data into standardized outcome variables. RESULTS: On weekdays, there were group differences in moderate physical activity between all lifestyle groups (OOA > OOM > USK > RSK). On the weekend, the group differences in moderate physical activity persisted between, but not within, lifestyle groups (OOA = OOM > USK = RSK). During school hours, all groups had similar activity and inactivity periods; however, they differed in magnitude, with the OOA and OOM being both more sedentary and more active. In comparison with the children in school, the OOA and the OOM children had 44% lower sedentary time out of school compared with only 15% lower for RSK and USK children. CONCLUSIONS: Although cross sectional, these data suggest that contemporary/modern living is associated with lower levels of moderate- and vigorous-intensity physical activity compared with lifestyles representative of earlier generations. Analyzing the physical activity and inactivity patterns of traditional lifestyle groups such as the OOA and the OOM can provide valuable insight into the quantity and quality of physical activity necessary to promote health.
Abstract: Despite widespread use of accelerometers to objectively monitor physical activity among adults and youth, little attention has been given to older populations. The purpose of this study was to define an accelerometer-count cut point for a group of older adults and to then assess the group's physical activity for 7 days. Participants (N = 38, age 69.7 +/- 3.5 yr) completed a laboratory-based calibration with an Actigraph 7164 accelerometer. The cut point defining moderate to vigorous physical activity (MVPA) was 1,041 counts/min. On average, participants obtained 68 min of MVPA per day, although more than 65% of this occurred as sporadic activity. Longer bouts of activity occurred in the morning (6 a.m. to 12 p.m.) more frequently than other times of the day. Almost 14 hr/day were spent in light-intensity activity. This study demonstrates the rich information that accelerometers provide about older adult activity patterns-information that might further our understanding of the relationship between physical activity and healthy aging.
Abstract: BACKGROUND: Mothers with higher levels of education are more likely to engage in health-promoting behaviour; thus, it is intuitive that a child's physical activity would be positively related to maternal education. The literature on this area, however, is inconclusive and may be due to the methods used to assess physical activity (i.e. the use of aggregated and self-reported physical activity that may not reflect the true and detailed variation of physical activity). AIM: To profile the physical activity behaviours of girls with mothers of differing educational attainment. SUBJECTS AND METHODS: 77 girls (grades 4-8) wore an Actical accelerometer for 7 days. Minutes spent sedentary and in light, moderate and vigorous physical activity per day over 7 days, 5 weekdays, 2 weekends, and 1 h commuting period to and from school of girls of University educated (UE) and non-UE mothers were analysed. RESULTS: After controlling for confounders, girls with UE mothers were more likely to participate in vigorous physical activity at the weekend and moderate-to-vigorous physical activity during the morning commute to school. CONCLUSIONS: Research investigating the relationship between maternal education and child's physical activity should explore, at higher resolution, when activity is accumulated, in particular separating weekday and weekend physical activity.
Abstract: The paper briefly reviews the status and trends in physical activity, physical inactivity, and overweight/obesity in Canada; discusses the consequences of these trends; examines evidence that our frame of reference with respect to physical activity and obesity is changing; promotes the importance of getting "back to the basics" as a strategy for enhancing childhood physical activity; and provides suggestions for future research in this area. In addressing these topics, the paper explores and contrasts the lifestyles and characteristics of Old Order Amish and Old Order Mennonite children with children exposed to contemporary modern living. This exploration is used as a model to learn from traditional lifestyles, which were comparatively active and resistant to obesity. The fitness characteristics and physical activity levels of traditional and contemporary groups are compared and demonstrate significant differences among groups. This evidence may provide important insight for informing future physical activity recommendations. Idiosyncrasies of performing research on these traditional-living groups are also provided.
Abstract: PURPOSE: To investigate whether observed gender differences in objectively measured physical activity (PA) in children (8-13 yr) are confounded by physical maturity differences. METHODS: Four hundred and one children (194 boys and 207 girls) volunteered for this study. An Actigraph accelerometer was used to obtain seven consecutive days of minute-by-minute PA data for each participant. Minutes of moderate to vigorous PA per day (MVPA), continuous minutes of MVPA per day (CMVPA), and minutes of vigorous PA per day (VPA) were derived from the accelerometer data. Age at peak height velocity (APHV), an indicator of somatic maturity, was predicted in all individuals. Gender differences in the PA variables were analyzed using a two-way (gender x age) ANOVA. RESULTS: Levels of PA decreased with increasing chronological age in both genders (P < 0.05). When aligned on chronological age, boys had a higher MVPA at 10-13 yr, a higher CMVPA at 9-12 yr, and a higher VPA at 9-13 yr (P < 0.05). When aligned on biological age, PA declined with increasing maturity (P < 0.05); however, gender differences between biological age groups disappeared. CONCLUSION: The observed age-related decline in adolescent boys and girls PA is antithetical to public health goals; as such, it is an important area of research. To fully understand gender disparities in PA, consideration must be given to the confounding effects of physical maturity.
Abstract: This article summarizes the main findings from the papers included in this journal supplement. It consolidates the evidence currently available to inform and advance the development of physical activity guidelines for Canadians, and it highlights the specific needs of various population subgroups. The challenges of translating guideline information into effective and persuasive physical activity messages, of campaigns to disseminate messages and of related evaluations are underlined. Recommendations on how to proceed are based on the evidence base provided by this series of papers; the immediate next steps mandated by this initiative are outlined and priorities for future research are indicated.
Abstract: The accurate measurement of habitual physical activity is fundamental to the study of the relationship between physical activity and health. However, many physical activity measurement techniques produce variables accurate to only the day level, such as total energy expenditure via self-report questionnaire, pedometer step counts, or accelerometer measurements of minutes of moderate to vigorous physical activity. Monitoring technologies providing more detailed information on physical activity and inactivity behaviour can now be used to explore the relationships between health and movement frequency, intensity, and duration more comprehensively. This paper explores the activity-inactivity profile that can be acquired through objective monitoring, with a focus on accelerometry. Using previously collected objective data, a detailed physical activity profile is presented and case study examples of data utilization and interpretation are provided. The rich detail captured through comprehensive profiling creates new surveillance and study possibilities and could possibly inform new physical activity guidelines. Data are presented in various formats to demonstrate the dangers of misinterpretation when monitoring population adherence to Canada's physical activity guidelines. Recommendations for physical activity-inactivity profiling are provided and future research needs identified.
Abstract: The prevalence of childhood obesity is rapidly increasing in many countries throughout the world. Advances in modern technology may have contributed to this problem by reducing children's physical activity levels. Thus, it is interesting to study children belonging to groups that have refrained from adopting modern technology. PURPOSE: This study examined the physical activity levels and body mass index (BMI) of Old Order Amish children and adolescents living in a nontechnological farming community. METHODS: One hundred thirty-nine Amish youth (6-18 yr of age) were recruited for the study. BMI was computed from measured height and weight. The schoolchildren were instructed to wear sealed step counters for 7 d. Each school day, research assistants opened the step counters, recorded their steps, reset and resealed them, and placed them back on the children. Older children recorded their steps on a step-counter log sheet. RESULTS: The number of steps per day (mean +/- SD) was 17,525 +/- 4443 (measured for four weekdays), 10,661 +/- 4208 (measured over Friday, Saturday, and Sunday), and 15,563 +/- 3702 (measured for 7 d). All of the step variables (P < 0.001) showed gender effects, but there were no significant age effects. Only 7.2% of the youth were overweight, and only 1.4% were obese. CONCLUSION: These Amish youth have high levels of physical activity, and obesity is rare. Comparing our results with those of other studies, it is evident that these Amish youth are more physically active and have a lower rate of obesity than children living in modern, industrialized societies.
Abstract: Canadian public health messages relating to physical activity have historically focused on the prescription of purposeful exercise, most often assessing leisure-time physical activity (LTPA). Although LTPA contributes to total energy expenditure (TEE), a large part of the day remains neglected unless one also considers the energy expended outside of purposeful exercise. This paper reviews the potential impact of incidental (non-exercise or non-purposeful) physical activity and lifestyle-embedded activities (chores and incidental walking) upon TEE and indicators of health. Given that incidental movement occurs sporadically throughout the day, this form of energy expenditure is perhaps most vulnerable to increasingly ubiquitous mechanization and automation. The paper also explores the relationship of physical inactivity, including sleep, to physical activity, TEE, and health outcomes. Suggestions are provided for a more comprehensive physical activity recommendation that includes all components of TEE. Objective physical activity monitors with time stamps are considered as a better means to capture and examine human movements over the entire day.
Abstract: The purpose of this study was to determine the effects of age and leg length on the energy-expenditure predictions of five activity monitors. Participants (N=86, ages 8-40 years) performed three progressive bouts of treadmill activity ranging from 4 to 12 km/hr. Differences between measured energy expenditure (VO2) and activity-monitor-predicted energy expenditure were assessed across five leg length categories to determine the influence of leg length. Accelerometer counts or pedometer steps along with age, weight, and leg length accounted for 85-94% of measured energy expenditure. The addition of age and leg length as predictor variables explained a larger amount of variance in energy expenditure across all speeds. Differences in leg length and age might affect activity-monitor validity and, therefore, should be controlled for when estimating physical activity energy expenditure.
Abstract: This article summarizes the main findings from the papers included in this journal supplement. It consolidates the evidence currently available to inform and advance the development of physical activity guidelines for Canadians, and it highlights the specific needs of various population subgroups. The challenges of translating guideline information into effective and persuasive physical activity messages, of campaigns to disseminate messages, and of related evaluations are underlined. Recommendations on how to proceed are based on the evidence base provided by this series of papers; the immediate next steps mandated by this initiative are outlined and priorities for future research are indicated.
Abstract: PURPOSE: To assess the validity of the new Actical accelerometer step count function. METHODS: Actical step counts were compared according to two criterion standards. 1) Eight Acticals were assessed using a mechanical shaker table under six different testing conditions. 2) Thirty-eight volunteers (aged 9-59 yr) wore eight Acticals and eight Actigraphs during treadmill walking (50 and 83 m.min(-1)) and running (133 m.min(-1)) for 6 min at each speed. Steps were counted during the second and fourth minutes of each speed by a trained observer. RESULTS: The correlation between Actical step counts and the mechanical shaker step counts was excellent (r = 1.0). Compared with visually counted steps, both the Actical and Actigraph step counts were significantly different at 50 m.min(-1); however, no significant differences were evident at 83 and 133 m.min(-1). The criterion-related validity correlations (r) for the Actical and Actigraph, respectively, were 0.73 and 0.52 at the slow walk condition and 0.99 and 0.99 at the normal walk and run conditions. CONCLUSION: The new step count function of the Actical accelerometer provides valid estimates of step counts at 83 and 133 m.min(-1) on a range of healthy participants.
Abstract: Canadian public health messages relating to physical activity have historically focused on the prescription of purposeful exercise, most often assessing leisure-time physical activity (LTPA). Although LTPA contributes to total energy expenditure (TEE), a large part of the day remains neglected unless one also considers the energy expended outside of purposeful exercise. This paper reviews the potential impact of incidental (non-exercise or non-purposeful) physical activity and lifestyle-embedded activities (chores and incidental walking) upon TEE and indicators of health. Given that incidental movement occurs sporadically throughout the day, this form of energy expenditure is perhaps most vulnerable to increasingly ubiquitous mechanization and automation. The paper also explores the relationship of physical inactivity, including sleep, to physical activity, TEE, and health outcomes. Suggestions are provided for a more comprehensive physical activity recommendation that includes all components of TEE. Objective physical activity monitors with time stamps are considered as a better means to capture and examine human movements over the entire day.
Abstract: The accurate measurement of habitual physical activity is fundamental to the study of the relationship between physical activity and health. However, many physical activity measurement techniques produce variables accurate to only the day level, such as total energy expenditure via self-report questionnaire, pedometer step counts, or accelerometer measurements of minutes of moderate to vigorous physical activity. Monitoring technologies providing more detailed information on physical activity and inactivity behaviour can now be used to explore the relationships between health and movement frequency, intensity, and duration more comprehensively. This paper explores the activity-inactivity profile that can be acquired through objective monitoring, with a focus on accelerometry. Using previously collected objective data, a detailed physical activity profile is presented and case study examples of data utilization and interpretation are provided. The rich detail captured through comprehensive profiling creates new surveillance and study possibilities and could possibly inform new physical activity guidelines. Data are presented in various formats to demonstrate the dangers of misinterpretation when monitoring population adherence to Canada's physical activity guidelines. Recommendations for physical activity-inactivity profiling are provided and future research needs identified.
Abstract: The Canadian Health Measures Survey (CHMS) pre-test was conducted to provide information about the challenges and costs associated with administering a physical health measures survey in Canada. To achieve the specific objectives of the pre-test, protocols were developed and tested, and methods for household interviewing and clinic testing were designed and revised. The cost, logistics and suitability of using fixed sites for the CHMS were assessed. Although data collection, transfer and storage procedures are complex, the pre-test experience confirmed Statistics Canada's ability to conduct a direct health measures survey and the willingness of Canadians to participate in such a health survey. Many operational and logistical procedures worked well and, with minor modifications, are being employed in the main survey. Fixed sites were problematic, and survey costs were higher than expected.
Abstract: PURPOSE: We determined the effects of conjugated linoleic acid (CLA) supplementation during resistance training. METHODS: Seventy-six subjects were randomized to receive CLA (5 g.d(-1)) or placebo (PLA) for 7 wk while resistance training 3 d.wk(-1). Seventeen subjects crossed over to the opposite group for an additional 7 wk. Measurements at baseline, 7 wk, and 14 wk (for subjects in the crossover study) included body composition, muscle thickness of the elbow flexors and knee extensors, resting metabolic rate (RMR), bench and leg press strength, knee extension torque, and urinary markers of myofibrillar degradation (3-methylhistidine (3MH) and bone resorption (cross-linked N-telopeptides (Ntx)). RESULTS: After 7 wk the CLA group had greater increases in lean tissue mass (LTM) (+1.4 vs +0.2 kg; P < 0.05), greater losses of fat mass (-0.8 vs +0.4 kg; P < 0.05), and a smaller increase in 3MH (-0.1 vs + 1.3 micromol.kg LTM.d(-1); P < 0.05) compared with PLA. Changes between groups were similar for all other measurements, except for a greater increase in bench press strength for males on CLA (P < 0.05). In the crossover study subjects had minimal changes in body composition, but smaller increases in 3MH (-1.2 vs +2.2 micromol.kg LTM.d(-1); P < 0.01) and NTx (-4.8 vs +7.3 nmol.kg(-1) LTM.d(-1); P < 0.01) while on CLA versus PLA. CONCLUSIONS: Supplementation with CLA during resistance training results in relatively small changes in body composition accompanied by a lessening of the catabolic effect of training on muscle protein.
Abstract: PURPOSE: To determine which of the three most commonly used accelerometer models has the best intra- and interinstrument reliability using a mechanical laboratory setup. Secondly, to determine the effects that acceleration and frequency have on these reliability measures. METHODS: Three experiments were performed. In the first, five each of the Actical, Actigraph, and RT3 accelerometers were placed on a hydraulic shaker plate and simultaneously accelerated in the vertical plane at varying accelerations and frequencies. Six different conditions of varying intensity were used to produce a range of accelerometer counts. Reliability was calculated using standard deviation, standard error of the measurement, coefficient of variation, and intraclass correlation coefficients. In the second and third experiments, 39 Actical and 50 Actigraph accelerometers were put through the same six conditions. RESULTS: Experiment 1 showed poor reliability in the RT3 (intra- and interinstrument CV > 40%). Experiments 2 and 3 clearly indicated that the Actical (CVintra = 0.5%, CVinter = 5.4%) was more reliable than the Actigraph (CVintra = 3.2%, CVinter = 8.6%). Variability in the Actical was negatively related to the acceleration of the condition, whereas no relationship was found between acceleration and reliability in the Actigraph. Variability in the Actigraph was negatively related to the frequency of the condition, whereas no relationship was found between frequency and reliability in the Actical. CONCLUSION: Of the three accelerometer models measured in this study, the Actical had the best intra- and interinstrument reliability. However, discrepant trends in the variability of Actical and Actigraph counts across accelerations and frequencies preclude the selection of a superior model. More work is needed to understand why accelerometers designed to measure the same thing behave so differently.
Abstract: PURPOSE: The primary purpose of this study was to compare the health-related physical fitness and physical activity behaviors of Old Order Mennonite children to both rural and urban-dwelling children living a contemporary Canadian lifestyle. METHODS: A cross-sectional study design was used to compare the physical fitness and physical activity characteristics of three groups of children between the ages of 8-13 yr. A total of 124 Old Order Mennonite children (OOM) from Ontario, Canada, were compared with contemporary living children from urban (USK, N = 110) and rural (RSK, N = 165) Saskatchewan, Canada. Fitness was assessed using measures of height, weight, triceps skinfold, grip strength, push-ups, partial curl-ups, and aerobic fitness. Physical activity levels were directly measured for seven consecutive days using a MTI Actigraph accelerometer model 7164. RESULTS: After controlling for maturational age, analyses revealed that OOM children had a smaller triceps skinfold than USK children (P < 0.01), a greater aerobic fitness score than RSK children (P < 0.05), and greater grip strength than both RSK and USK children (P < 0.001). The OOM children also accumulated more minutes of MVPA per day than RSK or USK groups (P < 0.001). CONCLUSION: This research demonstrates that OOM children tend to be leaner, stronger and more active than urban and rural dwelling children living a contemporary Canadian lifestyle despite having no physical education, no institutionalized sport, and low socioeconomic status. These findings support the notion that that contemporary living may facilitate a decline in fitness and physical activity among some Canadian children.
