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Deirdre M. Harrington, Kieran P. Dowd, Catrine Tudor-Locke and Alan E. Donnelly

The number of steps/minute (i.e., cadence) that equates to moderate intensity in adolescents is not known. To that end, 31 adolescent females walked on a treadmill at 5 different speeds while wearing an ActivPAL accelerometer and oxygen uptake was recorded by indirect calorimetry. The relationship between metabolic equivalents (METs) and cadence was explored using 3 different analytical approaches. Cadence was a significant predictor of METs (r=.70; p<.001). Moderate intensity (3 METs) corresponded to 94 or 114 steps/minute based on the mixed model and ROC analysis, respectively. These two values, and a practical value of 100 steps/minute, were cross-validated on an independent sample of 33 adolescent females during over-ground walking at 3 speeds. The sensitivity and specificity of each value correctly identifying 3 METs were 98.5% and 87.2% for 94 steps/minute, 72.9% and 98.8 for 114 steps/minute and 96.5% and 95.7% for 100 steps/minute. Compromising on a single cadence of 100 steps/minute would be a practical value that approximates moderate intensity in adolescent females and can be used for physical activity interpretation and promotion.

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Kieran P. Dowd, Helen Purtill, Deirdre. M. Harrington, Jane F. Hislop, John J. Reilly and Alan E. Donnelly

Objectives:

This study aims to determine the minimum number of days of monitoring required to reliably predict sitting/lying time, standing time, light intensity physical activity (LIPA), moderate-to-vigorous intensity physical activity (MVPA) and steps in adolescent females.

Method:

195 adolescent females (mean age = 15.7 years; SD = 0.9) participated in the study. Participants wore the activPAL activity monitor for a seven day protocol. The amount of time spent sitting/lying, standing, in LIPA and in MVPA and the number of steps per day were quantified. Spearman-Brown Prophecy formulae were used to predict the number of days of data required to achieve an intraclass correlation coefficient of both 0.7 and 0.8.

Results:

For the percentage of the waking day spent sitting/lying, standing, in LIPA and in MVPA, a minimum of 9 days of accelerometer recording is required to achieve a reliability of ≥ 0.7, while a minimum of 15 days is required to achieve a reliability of ≥ 0.8. For steps, a minimum of 12 days of recording is required to achieve a reliability of ≥ 0.7, with 21 days to achieve a reliability of ≥ 0.8.

Conclusion:

Future research in adolescent females should collect a minimum of 9 days of accelerometer data to reliably estimate sitting/lying time, standing time, LIPA and MVPA, while 12 days is required to reliably estimate steps.

Open access

Deirdre M. Harrington, Marie Murphy, Angela Carlin, Tara Coppinger, Alan Donnelly, Kieran P. Dowd, Teresa Keating, Niamh Murphy, Elaine Murtagh, Wesley O’Brien, Catherine Woods and Sarahjane Belton

Background:

Physical activity (PA) is a key performance indicator for policy documents in both the Republic of Ireland and Northern Ireland. Building on baseline grades set in 2014, Ireland’s second Report Card on Physical Activity for Children and Youth allows for continued surveillance of indicators related to PA in children and youth.

Methods:

Data and information were extracted and collated for 10 indicators and graded using an international standardized grading system.

Results:

Overall, 7 grades stayed the same, 2 increased, and 1 decreased. Grades were assigned as follows: Overall PA, D (an increase); Sedentary Behavior (TV), C-; Physical Education, D-; Active Play, Incomplete/Inconclusive (INC); Active Transportation, D; School, D (a decrease); Home (Family), INC; Community and the Built Environment, B+ (an increase); and Government, INC. Unlike 2014’s report card, different grades for the Republic (C-) and Northern Ireland (C+) were assigned for Organized Sport Participation.

Conclusions:

Although the grade for Overall PA levels increased to a D, this may reflect the increased quality and quantity of data available. The double burden of low PA and high sedentary levels are concerning and underscore the need for advocacy toward, and surveillance of, progress in achieving targets set by the new National Physical Activity Plan in the Republic and obesity and sport plans in the North.

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Kieran Dowd, Deidre Harrington, Ailish Hannigan, Helen Purtill, Sarah M. Kelly, Alan P. Macken, Niall Moyna, Clodagh S. O’Gorman and Alan E. Donnelly

Objectives:

This study aims to (1) use the objective activPAL activity monitor to assess physical activity behaviors, including sitting/lying, standing, and both light (LIPA) and moderate-to-vigorous physical activity (MVPA); (2) to develop distinct activity profiles based on time spent in each behavior in a sample of adolescent females; and (3) examine whether levels of adiposity differ across these activity profiles.

Methods:

Female adolescents (n = 195; 14–18 y) had body mass index (median = 21.7 [IQR = 5.2] kg/m2) and 4-site skinfold thickness (median 62.0 mm; IQR = 37.1) measured. Physical activity behaviors were measured using the activPAL. Hierarchical cluster analysis grouped participants into activity profiles based on similar physical activity characteristics. Linear mixed models explored differences in body composition across activity profiles.

Results:

Three activity profiles were identified, a low (n = 35), moderate (n = 110), and a high activity profile (n = 50). Significant differences across activity profiles were observed for skinfold thickness (p = .046), with higher values observed in the low activity profile compared with the high activity profile.

Conclusions:

Profiling free-living activity using behaviors from across the activity intensity continuum may account for more of the variability in energy expenditure then examining specific activity intensities, such as MVPA alone. The use of activity profiles may enable the identification of individuals with unhealthy activity behaviors, leading to the development and implementation of more targeted interventions.