This study evaluated the effectiveness of an open-loop system that reinforces physical activity with TV watching to increase children’s physical activity. Nonoverweight, sedentary boys and girls (8–12 y) were randomized to a group that received feedback of activity counts + reinforcement for physical activity by providing access to television (F+R, n = 20); or to feedback, no reinforcement (Feedback, n = 20) or no feedback, no reinforcement control (Control, n = 21) groups. Children wore an accelerometer with a count display for 4-months with a 1-year follow-up. F+R reduced TV by 68 min/day and TV time was lower than the Feedback (p < .005) and Control (p < .002) groups. TV time of F+R remained 31 min lower (p < .02) than baseline at 1-year. F+R had a 44% increase in physical activity, which was greater than the feedback (p < .04) and control (p < .01) groups. An open-loop system decreases TV viewing and increases physical activity of children for 4-months. TV of the F+R group remained lower at 12 months, suggesting a reduction in screen-time habits.
James N. Roemmich, Christina L. Lobarinas, Jacob E. Barkley, Tressa M. White, Rocco Paluch and Leonard H. Epstein
Steven P. Hooker, Anna Feeney, Brent Hutto, Karin A. Pfeiffer, Kerry McIver, Daniel P. Heil, John E. Vena, Michael J. LaMonte and Steven N. Blair
This study was designed to validate the Actical activity monitor in middle-aged and older adults of varying body composition to develop accelerometer thresholds to distinguish between light and moderate intensity physical activity (PA).
Nonobese 45 to 64 yr (N = 29), obese 45 to 64 yr (N = 21), and ≥65 yr (N = 23; varying body composition) participants completed laboratory-based sitting, household, and locomotive activities while wearing an Actical monitor and a portable metabolic measurement system. Nonlinear regression analysis was used to identify activity count (AC) cut-points to differentiate between light intensity (<3 METs) and moderate intensity (≥3METs) PA.
Using group-specific algorithms, AC cut points for 3 METs were 1634, 1107, and 431 for the obese 45 to 64 yr group, nonobese 45 to 64 yr group, and ≥65 yr group, respectively. However, sensitivity and specificity analysis revealed that an AC cut-point of 1065 yielded similar accuracy for detecting an activity as less than or greater than 3 METs, regardless of age and body composition.
For the Actical activity monitor, an AC cut-point of 1065 can be used to determine light and moderate intensity PA in people ≥45 years of age.
James LeCheminant, Larry Tucker and Kenric Russell
This study investigated the relationship between objectively-measured total physical activity (PA), and intensity of PA and high-sensitivity C-reactive protein (CRP) in 211 healthy, middle-age women (43.1 ± 3.0 y). In addition, this study examined the extent to which age, BMI, abdominal circumference, and body fat percentage operated as confounders in these associations.
PA was objectively measured for 7 continuous days using accelerometry. Fasting blood samples were taken, from which CRP was measured using a solid phase ELISA. Body mass index (BMI) (kg/m2), abdominal circumference measured at the umbilicus, and body fat percentage using air displacement plethysmography, were assessed.
Total PA (activity counts) was significantly and inversely related to CRP concentrations (F = 7.76, P = .006) as was vigorous-intensity PA. After adjusting for differences in body fat percentage, total PA and vigorous-intensity PA were no longer significant predictors of CRP. Abdominal circumference and BMI also tended to weaken the relationship between total or vigorous-intensity PA and CRP but not to the same extent as body fat percentage.
These findings suggest that higher total and vigorous-intensity PA levels are significantly related to lower CRP levels in healthy, middle-age women; however, this relationship is largely a function of differences in body fat percentage.
Anders Raustorp, Peter Pagels, Cecilia Boldemann, Nilda Cosco, Margareta Söderström and Fredrika Mårtensson
It is important to understand the correlates of physical activity (PA) to influence policy and create environments that promote PA among preschool children. We compared preschoolers’ PA in Swedish and in US settings and objectively examined differences boys’ and girls’ indoor and outdoor PA regarding different intensity levels and sedentary behavior.
Accelerometer determined PA in 50 children with mean age 52 months, (range 40–67) was recorded during preschool time for 5 consecutive weekdays at 4 sites. The children wore an Actigraph GTIM Monitor.
Raleigh preschool children, opposite to Malmö preschoolers spent significantly more time indoors than outdoors (P < .001). Significantly more moderate-to-vigorous intensity physical activity (MVPA) was observed outdoors (P < .001) in both settings. Malmö children accumulated significantly more counts/min indoors (P < .001). The percent of MVPA during outdoor time did not differ between children at Raleigh and Malmö.
Physical activity counts/minutes was significantly higher outdoors vs. indoors in both Malmö and Raleigh. Malmö preschoolers spent 47% of attendance time outdoors compared with 18% for Raleigh preschoolers which could have influenced the difference in preschool activity between the 2 countries. Time spent in MVPA at preschool was very limited and predominantly adopted outdoors.
Anna Goodman, James Paskins and Roger Mackett
Children in primary school are more physically active in the spring/summer. Little is known about the relative contributions of day length and weather, however, or about the underlying behavioral mediators.
325 British children aged 8 to 11 wore accelerometers as an objective measure of physical activity, measured in terms of mean activity counts. Children simultaneously completed diaries in which we identified episodes of out-of-home play, structured sports, and active travel. Our main exposure measures were day length, temperature, rainfall, cloud cover, and wind speed.
Overall physical activity was higher on long days (≥ 14 hours daylight), but there was no difference between short (< 9.5 hours) and medium days (10.2–12.6 hours). The effect of long day length was largest between 5 PM and 8 PM, and persisted after adjusting for rainfall, cloud cover, and wind. Up to half this effect was explained by a greater duration and intensity of out-of-home play on long days; structured sports and active travel were less affected by day length.
At least above a certain threshold, longer afternoon/evening daylight may have a causal role in increasing child physical activity. This strengthens the public health arguments for daylight saving measures such as those recently under consideration in Britain.
E. Andrew Pitchford, Leah R. Ketcheson, Hyun-Jin Kwon and Dale A. Ulrich
Research measuring physical activity behaviors during infancy is critical for evaluation of early intervention efforts to reduce rapid weight gain. There is little known about the physical activity patterns of infants, due in part to limited evidence for measurement procedures. This study sought to determine the minimal number of days and hours of accelerometry needed to reliably measure daily physical activity in infants using Generalizability (G) theory.
A total of 23 infants (14 female, 9 male) wore an accelerometer on the right ankle and right wrist for 7 days. Data were manually cleaned to remove activity counts not produced by the infant. G theory analyses were conducted on the average counts per epoch.
Reliable estimates were observed with at least 2 days (G & Φ = .910) and 12 hours (G = .806, Φ = .803) at the ankle, and with at least 3 days (G & Φ = .906) and 15 hours (G = .802, Φ = .800) at the wrist.
These results provide some of the first guidelines for objective physical activity measurement during infancy. Accelerometer monitoring periods of at least 3 days including all daytime hours appear to be sufficient for reliable measurement.
Alex V. Rowlands
The total activity volume performed is an overall measure that takes into account the frequency, intensity, and duration of activities performed. The importance of considering total activity volume is shown by recent studies indicating that light physical activity (LPA) and intermittent moderate-to-vigorous physical activity (MVPA) have health benefits. Accelerometer-derived total activity counts (TAC) per day from a waist-worn accelerometer can serve as a proxy for an individual’s total activity volume. The purpose of this study was to develop age- and gender-specific percentiles for daily TAC, minutes of MVPA, and minutes of LPA in U.S. youth ages 6-19 y.
Data from the 2003-2006 NHANES waist-worn accelerometer component were used in this analysis. The sample was composed of youth aged 6-19 years with at least 4 d of ≥10 hr of accelerometer wear time (N = 3698). MVPA was defined using age specific cutpoints as the total number of minutes at ≥4 metabolic equivalents (METs) for youth 6-17 y or minutes with ≥2020 counts for youth 18-19 y. LPA was defined as the total number of minutes between 100 counts and the MVPA threshold. TAC/d, MVPA, and LPA were averaged across all valid days.
For males in the 50th percentile, the median activity level was 441,431 TAC/d, with 53 min/d of MVPA and 368 min/d of LPA. The median level of activity for females was 234,322 TAC/d, with 32 min/d of MVPA and 355 min/d of LPA.
Population referenced TAC/d percentiles for U.S. youth ages 6-19 y provide a novel means of characterizing the total activity volume performed by children and adolescents.
Erik A. Willis, Amanda N. Szabo-Reed, Lauren T. Ptomey, Jeffery J. Honas, Felicia L. Steger, Richard A. Washburn and Joseph E. Donnelly
assessed in the participant using the calorimeter was representative of the group, we compared percent HR max and physical activity (counts/min) in the participants wearing the calorimeter to the study and to not wearing the calorimeter. Each participant completed one session wearing an indirect
Charity B. Breneman, Christopher E. Kline, Delia West, Xuemei Sui and Xuewen Wang
exercise in postmenopausal women—specifically, wake after sleep onset (WASO), number of awakenings, and activity counts ( Wang & Youngstedt, 2014 ). Therefore, we hypothesized that these sleep outcomes were most likely to be impacted by an acute bout of exercise among postmenopausal women in an exercise
Katja Krustrup Pedersen, Esben Lykke Skovgaard, Ryan Larsen, Mikkel Stengaard, Søren Sørensen and Kristian Overgaard
, & Holtermann, 2014 ). Accelerometers record accelerations as a person moves, and the output measure extracted from accelerometers (e.g., ActiGraph GT3X+) is typically “activity counts” derived from the collected raw acceleration data. In order to translate activity counts into a meaningful outcome variable