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DESCRIPTIVE ANALYSES OF LONGITUDINAL (MULTI-DAY) VARIABILITY IN SELECTED TIME- USE DATA CONTAINED IN EPA'S CONSOLIDATED HUMAN ACTIVITY DATABASE (CHAD)
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The number of days of food intake data needed to estimate the intake of 29 male (n = 13) and female (n = 16) adult subjects, individually and as a group, was determined for food energy and 18 nutrients. The food intake records were collected in a year-long study conducted by the U.S. Department of Agriculture's Beltsville Human Nutrition Research Center. Each individual's average intake of nutrients and standard deviation over the year were assumed to reflect his or her “usual” intake and day-to-day variability. Confidence intervals (P < 0.05) for each individual's usual intake were constructed, and from these the number of days of dietary records needed for estimated individual and group intake to be within 10% of usual intake was calculated. The results indicated that the number of days of food intake records needed to predict the usual nutrient intake of an individual varied substantially among individuals for the same nutrient and within individuals for different nutrients; e.g., food energy required the fewest days (averaging 31) and vitamin A the most (averaging 433). This was considerably higher than the number of days needed to estimate mean nutrient intake for this group, which ranged from 3 for food energy to 41 for vitamin A. Fewer days would be needed for larger groups.
Background
To more accurately quantify the potential impact of the neighbourhood environment on adults’ physical activity (PA), it is important to compare environment-PA associations between periods of the day or week when adults are more versus less likely to be in their neighbourhood and utilise its PA resources. We examined whether, among adults from 10 countries, associations between objectively-assessed neighbourhood environment attributes and moderate-to-vigorous physical activity (MVPA) varied by time of the day and day of the week. The secondary aim was to examine whether such associations varied by employment status, gender and city. Methods
This cross-sectional study included 6,712 adults from 14 cities across 10 countries with ≥1 day of valid accelerometer-assessed MVPA and complete information on socio-demographic and objectively-assessed environmental characteristics within 0.5 and 1 km street-network buffers around the home. Accelerometer measures (MVPA min/h) were created for six time periods from early morning until late evening/night, for weekdays and weekend days separately. Associations were estimated using generalized additive mixed models. ResultsTime of the day, day of week, gender and employment status were significant moderators of environment-MVPA associations. Land use mix was positively associated with MVPA in women who were employed and in men irrespective of their employment status. The positive associations between MVPA and net residential density, intersection density and land use mix were stronger in the mornings of weekdays and the afternoon/evening periods of both weekdays and weekend days. Associations between number of parks and MVPA were stronger in the mornings and afternoon/evenings irrespective of day of the week. Public transport density showed consistent positive associations with MVPA during weekends, while stronger effects on weekdays were observed in the morning and early evenings. Conclusions
This study suggests that space and time constraints in adults’ daily activities are important factors that determine the impact of neighbourhood attributes on PA. Consideration of time-specific associations is important to better characterise the magnitude of the effects of the neighbourhood environment on PA. Future research will need to examine the contribution of built environment characteristics of areas surrounding other types of daily life centres (e.g., workplaces) to explaining adults’ PA at specific times of the day.
RATIONALE: Physical activity enhances uptake of air pollutants in the lung, possibly augmenting their harmful effects on chronic lung disease during exercise.
OBJECTIVES: To examine whether benefits of physical activity with respect to the risk of asthma and chronic obstructive pulmonary disease (COPD) are moderated by exposure to high air pollution levels in an urban setting.
METHODS: A total of 53,113 subjects (50-65 yr) from the Danish Diet, Cancer, and Health cohort reported physical activity at recruitment (1993-1997) and were followed until 2013 in the National Patient Register for incident hospitalizations for asthma and COPD. Levels of nitrogen dioxide (NO2) were estimated at subject residences at the time of recruitment. We used Cox regression to associate physical activities and NO2 (high/medium/low) with asthma and COPD, and then introduced an interaction term between each physical activity and NO2.
MEASUREMENTS AND MAIN RESULTS: A total of 1,151 subjects were hospitalized for asthma and 3,225 for COPD during 16 years. We found inverse associations of participation in sports (hazard ratio [95% confidence interval]: 0.85 [0.75-0.96]) and cycling (0.85 [0.75-0.96]) with incident asthma, and of participation in sports (0.82 [0.77-0.89]), cycling (0.81 [0.76-0.87]), gardening (0.88 [0.81-0.94]), and walking (0.85 [0.75-0.95]) with incident COPD admissions. We found positive associations between NO2 and incident asthma (1.23 [1.04-1.47]) and COPD (1.15 [1.03-1.27]) hospitalizations (comparing ≥21.0 μg/m3 to <14.3 μg/m3). We found no interaction between associations of any physical activity and NO2 on incident asthma or COPD hospitalizations.
CONCLUSIONS: Increased exposure to air pollution during exercise does not outweigh beneficial effects of physical activity on the risk of asthma and COPD.
Physical activity and ventilation rates have an effect on an individual's dose and may be important to consider in exposure-response relationships; however, these factors are often ignored in environmental epidemiology studies. The aim of this study was to evaluate methods to estimate the inhaled dose of air pollution and understand variability, in the absence of a true gold standard metric. Five types of methods were identified: (1) methods using (physical) activity types; (2) methods based on energy expenditure, METs (metabolic equivalents of task) and oxygen consumption; (3) methods based on heart rate or (4) breathing rate; and (5) methods that combine heart and breathing rate. Methods were compared using a real-life dataset of 122 adults who wore devices to track movement, black carbon air pollution and physiological health markers for three weeks in three European cities. Different methods to estimate minute ventilation performed well in relative terms with high correlations among different methods. But in absolute terms, ignoring increased ventilation during day to day activities could lead to an underestimation of daily dose by a factor 0.08 to 1.78. There is no single best method and a multitude of methods are currently being used to approximate dose. The choice of a suitable method to determine dose in future studies will depend both on the size and the objectives of the study.
Purpose:
To test the feasibility and reliability of a direct observation method for measuring moderate to vigorous physical activity (MVPA) in children visiting an interactive children's museum exhibition.
Design:
Direct observation was used to assess MVPA in children visiting an interactive children's museum exhibition on 2 weekend days in winter 2013.
Setting:
The Children's Museum of Manhattan's EatSleepPlay™: Building Health Every Day exhibition.
Participants:
Children (group level) visiting the museum exhibition.
Measures:
System for Observing Play and Leisure Activity in Youth (SOPLAY).
Analyses:
Interobserver reliability was analyzed for MVPA and activity type. Two-group analyses were conducted using a series of Wilcoxon rank sum tests.
Results:
A total of 545 children were observed over 288 observations. No significant differences were found between observers for MVPA (r = .91, P = .6804) or activity type (κ = .90, P = .6334). Children participated in MVPA during 35.2% of all observations. No significant differences were found for participation in MVPA between boys (37.6%) and girls (32.8%, P = .1589).
Conclusion:
The SOPLAY may be a useful tool for measuring MVPA in interactive children's museum exhibitions. Research with multiple museum settings and diverse groups of children over longer periods of time is warranted to further establish the feasibility and reliability of the SOPLAY for measuring MVPA in this novel setting.
Objective:
To examine whether accelerometer-measured PA-based reactivity was present in a nationally representative sample of U.S. children (6-11 yrs), adolescents (12-17 yrs) and adults (≥ 20 yrs).
Methods:
Data from the 2003-2006 NHANES (N = 674, 6-85 years) were used. PA was assessed using the ActiGraph 7164 accelerometer, with PA assessed over 7 days of monitoring. Two PA metrics were assessed, including activity counts per day (CPD) and time spent in moderate-to-vigorous physical activity (MVPA). Evidence of reactivity was defined as a statistically significantly change in either of these two PA metrics from day 1 of monitoring to days 2 or 3, with day 1 of monitoring being a Monday.
Results:
Suggestion of reactivity was observed only for the adult population where CPD from days two and three (297140.6 ± 7920.3 and 295812.9 ± 8364.9), respectively, differed significantly from day one (309611.5 ± 9134.9) over the monitoring period (4.0 - 4.5% change). The analysis was conducted 2 additional times with differing start days (Tuesday and Wednesday), and this approach failed to demonstrated a reactive presence.
Conclusion:
In this national sample of U.S. children, adolescents and adults, we did not observe sufficient evidence of accelerometer reactivity.
Studies of time-use are rather commonplace today. Central statistical bureaus in many countries have adopted the technique and are contemplating regular surveys. The idea that measurements of time and time-allocations can be used as general indicators of living conditions is taken up by many. Serious schemes have been developed that propose exchanging the well-known 'money-budget' for 'time-budgets'. Development programs for 'social indicators' all incorporate various measures based on time and time-use. It is fair to say, however, that this field of inquiry is still in its infancy. It has proved possible to obtain data on people's daily use of time with sufficient reliability, but there is an alarming lack of reports on the methodological difficulties involved. The studies performed are typically empirical, fact-finding surveys with little attention given to the theoretical issues involved. The dominant instrument of data-gathering is the '24-hour time diary'. The various studies follow a general pattern which makes comparison possible, but there is a great need for further development of this research instrument. This is readily understood by those who have ventured to use it. The traditional time-use studies are very expensive and require great inputs of both time and money. This paper will not deal with all the problems mentioned. First the concrete reality at hand will be dealt with and thereafter some major methodological problems illuminated. A framework for classifying activities is proposed and, finally, indication is given of how the 'diary approach' can possibly be adapted for inclusion in interview surveys.
Introduction:
The primary purpose of this study was to evaluate variability of sedentary behavior (SB) throughout a 7-day measurement period and to determine if < 7-days of SB measurement would be comparable to the typical 7-day measurement period.
Methods:
Retrospective data from Ball State University's Clinical Exercise Physiology Laboratory on 293 participants (99 men, 55±14 years, BMI = 29±5 kg/m; 194 women, 51±12 years, BMI = 27±7 kg/m) with 7 consecutive days of data collected with Actigraph accelerometers were analyzed. Time spent in SB (either < 100 cpm or <150 cpm) and breaks in SB were compared between days and by sex using a 2-way repeated measures ANOVA. Stepwise regression was performed to determine if < 7-days of SB measurement were comparable to the 7-day method; using an adjusted R of ≥0.9 as criterion for equivalence.
Results:
There were no differences in daily time spent in SB between the 7 days for all participants. However, there was a significant interaction between sex and days, with women spending less time in SB on both Saturdays and Sundays than men when using the 100 cpm cut-point. Stepwise regression showed using any 4 days would be comparable to a 7-day measurement (R>0.90).
Conclusion:
When assessed over a 7-day measurement period, SB appears to be very stable from day-to-day, although there may be some small differences in time spent in SB and breaks in SB between men and women, particularly on weekend days. The stepwise regression analysis suggests that a measurement period as short as 4 days could provide comparable data (91% of variance) to a one-week assessment. Shorter assessment periods would reduce both researcher and subject burden in data collection.