The primary aim of this study was to test the validity of two accelerometers, CSA/MTI WAM-7164 and Actiwatch®, against direct observation of physical activity using the Children’s Physical Activity Form (CPAF). CSA/MTI WAM-7164 and Actiwatch accelerometers simultaneously measured activity during structured-play classes in 3- to 4-year olds. Accelerometry output was synchronized to CPAF assessments of physical activity in 78 children. Rank order correlations between accelerometry and direct observation evaluated the ability of the accelerometers to assess total physical activity. Within-child minute-to-minute correlations were calculated between accelerometry output and direct observation. For total physical activity, CSA/MTI output was significantly correlated with CPAF (r = .72, p < .001), but output from the Actiwatch was not (r = .16, p > .05).
Louise A. Kelly, John J. Reilly, Sheila C. Fairweather, Sarah Barrie, Stanley Grant and James Y Paton
Sheila C. Fairweather, John J. Reilly, Stanley Grant, Arthur Whittaker and James Y. Paton
The primary aim of this study was to assess the ability of the CSA accelerometer to measure physical activity in preschool children. A secondary aim was to examine inter-instrument differences and the effect of accelerometer placement on output. Eleven subjects (mean age = 4.0 years, SD = 0.4) wore the CSA-7164 for a 45-min preschool exercise class. They were observed throughout the class, and their engagement in activity was quantified using the Children’s Physical Activity Form (CPAF). The effect of accelerometer positioning (left vs. right hip) was assessed in 10 subjects over 2 days. CSA output during the class was highly correlated with the CPAF score (r = 0.87, p < .001), and rank order correlations between the 2 methods were also highly significant (r = 0.79, p < .01). Differences in CSA output between left and right hip reached statistical significance (paired t, p < .05), but these differences were small and probably of limited biological significance. The CSA appears to be an appropriate tool for assessment of physical activity in preschool children, but further studies on stability of activity as measured by CSA, as well as its validity, are urged.
Anne Martin, Mhairi McNeill, Victoria Penpraze, Philippa Dall, Malcolm Granat, James Y. Paton and John J. Reilly
The Actigraph is well established for measurement of both physical activity and sedentary behavior in children. The activPAL is being used increasingly in children, though with no published evidence on its use in free-living children to date. The present study compared the two monitors in preschool children. Children (n 23) wore both monitors simultaneously during waking hours for 5.6d and 10h/d. Daily mean percentage of time sedentary (nontranslocation of the trunk) was 74.6 (SD for the Actigraph and 78.9 (SD 4.3) for activPAL. Daily mean percentage of time physically active (light intensity physical activity plus MVPA) was 25.4 (SD for the Actigraph and 21.1 (SD 4.3) for the activPAL. Bland-Altman tests and paired t tests suggested small but statistically significant differences between the two monitors. Actigraph and activPAL estimates of sedentary behavior and physical activity in young children are similar at a group level.
Louise A. Kelly, John J. Reilly, Diane M. Jackson, Colette Montgomery, Stanley Grant and James Y. Paton
Tracking of total physical activity (PA), moderate to vigorous activity (MVPA), and sedentary behavior was assessed in 42 young children (mean age at baseline 3.8 years) over a 2-year period using the Actigraph accelerometer. Tracking was analyzed using Spearman rank correlations, percentage agreements, and kappa statistics. Spearman rank correlations were r = .35 (p = .002) for total PA, r = .37 (p = .002) for MVPA, and r = .35 (p = .002) for sedentary behavior. Percentage agreements for PA, MVPA, and sedentary behavior were 38, 41, and 26 respectively. Kappa statistics for PA, MVPA, and sedentary behavior ranged from poor to fair. Results suggest low levels of tracking of total physical activity, MVPA, and sedentary behavior in young Scottish children over a 2-year period.
Abigail Fisher, John J. Reilly, Colette Montgomery, Louise A. Kelly, Avril Williamson, Diane M. Jackson, James Y. Paton and Stanley Grant
This study examined whether there was a significant seasonal variation in objectively measured habitual physical activity and sedentary behavior in young children. Participants were children who attend nursery in Glasgow, Scotland, and measurements were taken using uniaxial accelerometry over 3 to 6 days. There were small but significant seasonal associations with physical activity and sedentary behavior (ANOVA: p < .001 in both cases). Total physical activity (accelerometry cpm) was significantly lower in spring than in summer, fall, and winter. We also found slight but significant seasonal variations in time spent in low-intensity activity and in moderate-to-vigorous-intensity activity. Sedentary time was significantly lower in summer vs. spring and in fall vs. spring. The present study suggests that seasonality plays only a limited role in physical activity and sedentary behavior in young children in our setting. Single measures of these variables should be adequate for research purposes in the absence of marked seasonal variability. In our sample and setting, the limited degree of seasonality precluded identification of major seasonal barriers to and opportunities for physical activity.
Victoria Penpraze, John J. Reilly, Christina M. MacLean, Colette Montgomery, Louise A. Kelly, James Y. Paton, Thomas Aitchison and Stan Grant
There is limited evidence on how much and on which days accelerometry monitoring should be performed to obtain a representative measurement of physical activity (PA) in young children. We measured 76 children (40 M and 36 F, mean age 5.6 years ([SD ± 0.4]) on 7 days using Actigraph accelerometers. Mean daily PA was expressed in counts per min (cpm). Reliability increased as the number of days and hours of monitoring increased, but only to 10 hr per day. At 7 days of monitoring for 10 hr per day, reliability was 80% (95% CI [70%, 86%]). The number of days was more important to reliability than the number of hours. The inclusion or exclusion of weekend days made relatively little difference. A monitoring period of 7 days for 10 hr per day produced the highest reliability. Surprisingly short monitoring periods may provide adequate reliability in young children.