Calibration of Accelerometer Output for Children

Department of Exercise Science, University of Massachusetts, Amherst, MA 01003, USA.
Medicine &amp Science in Sports &amp Exercise (Impact Factor: 3.98). 12/2005; 37(11 Suppl):S523-30. DOI: 10.1249/
Source: PubMed


Understanding the determinants of physical activity behavior in children and youths is essential to the design and implementation of intervention studies to increase physical activity. Objective methods to assess physical activity behavior using various types of motion detectors have been recommended as an alternative to self-report for this population because they are not subject to many of the sources of error associated with children's recall required for self-report measures. This paper reviews the calibration of four different accelerometers used most frequently to assess physical activity and sedentary behavior in children. These accelerometers are the ActiGraph, Actical, Actiwatch, and the RT3 Triaxial Research Tracker. Studies are reviewed that describe the regression modeling approaches used to calibrate these devices using directly measured energy expenditure as the criterion. Point estimates of energy expenditure or count ranges corresponding to different activity intensities from several studies are presented. For a given accelerometer, the count cut points defining the boundaries for 3 and 6 METs vary substantially among the studies reviewed even though most studies include walking, running and free-living activities in the testing protocol. Alternative data processing using the raw acceleration signal is recommended as a possible alternative approach where the actual acceleration pattern is used to characterize activity behavior. Important considerations for defining best practices for accelerometer calibration in children and youths are presented.

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Available from: Kathleen F Janz, Oct 15, 2014
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    • "Time in MVPA During Sport . MVPA as determined in Freedson ' s accelerometric algorithm ( Freedson et al 2005 , #19 ) . Sports shown if that sex had >10 episodes during recording . "
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    ABSTRACT: Sporting activities differ in their ability to promote moderate-to-vigorous physical activity (MVPA). To assess adolescents' engagement in sport under field conditions we used accelerometers to measure their MVPA levels during sport. We pay special attention to differences between team and individual sport and between common sports. METHODS: Diary data and 7-day accelerometry from 1054 Germans ages 15-17 were combined to measure physical activity. 1373 diaried episodes of more than 40 common sports were identified from 626 participants and grouped into team and individual sport. We modeled the effect of team and individual sport, and described levels of MVPA and episodes of no MVPA for all recorded sports. RESULTS: German boys and girls averaged 43 (SD 21) and 37 (SD 24) minutes MVPA per day. Boys got 2.2 times as much MVPA per minute during team compared to individual sport (p<0.0001) but there was no significant difference for girls. Percent of time spent in MVPA during sport ranged from 6% for weight training to 74% for jogging, with individual sports averaging 10-30% and team sports 30-50%. 11% of sport episodes had no MVPA: half of episodes of cycling, 5% of jogging, and none for tennis or badminton. An episode of individual sport was 17 times more likely to have no MVPA than an episode of team sport (p<0.0001). CONCLUSION: Under field condition, adolescents were active for only a fraction of diaried sporting time. As measured by accelerometry, individual sport often produced no MVPA. Characteristics of the sport, such as team vs. individual, were more predictive of MVPA than were characteristics of the participant, such as background activity levels.
    PLoS ONE 08/2015; 10(9):e0135630. DOI:10.1371/journal.pone.0135630 · 3.23 Impact Factor
    • "Three hundred and ninety-six children met these criteria (valid days = 3.49 ± 0.52). Age specific cut-points were applied for MVPA as described by Freedson et al. (2005) and used in the National Health and Nutrition Examination Survey (NHANES) (Troiano et al., 2008). MVPA bouts, as described by Mark and Janssen (2009), were identified as sporadic sessions of activity (b 5 min); short bouts of activity (5–b10 min); and medium-to-long bouts of activity (≥10 min) were considered. "
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    ABSTRACT: Background: Accumulating moderate-to-vigorous physical activity (MVPA) in bouts of 10 min is associated with improved cardio-metabolic risk factors (CMRF) in adults. Purpose: To assess the association between the lengths of MVPA bouts and CMRF in elementary school age children. Methods: The sample included 396, 2nd and 3rd grade students from eastern Kansas (182 boys, 214 girls; age 7.6 ± 0.6 years; Body Mass Index Percentile [BMI%ile]: 61.6 ± 9.3) in the fall of 2011. Analyses were conducted in 2014. MVPA bouts were defined as sporadic (<5 min), short (5-<10 min) or medium-to-long (≥10 min). Latent profile analysis was used to identify distinct subgroups (classes) based on the composition of MVPA bouts. Bayesian probability-based Wald chi-square test was used to compare CMRF between classes controlling for age, sex, BMI%ile, and total moderate and total vigorous PA. Results: Three classes of accumulated physical activity were identified: A (n=78); 97% sporadic 2%, short, 1% medium-to-long bouts; B (n=174); 93% sporadic, 5% short, 2% medium-to-long; C (n=144); and 86% sporadic, 9% short, 5% medium-to-long bouts. Class C had significantly lower BMI%ile (57.3 ± 2.3 (SE)), waist circumference (WC; 55.8 ± 0.5 cm) compared with Class A (BMI%ile=70.9±0.5, p<0.01.030, WC=61.0 ± 1.0 cm, p=0.<0.01). Class B had significantly lower WC (56.6 ± 0.6 cm), p<0.01 than Class A. No significant differences between classes were shown in other outcomes. Conclusion: Children who accumulated MVPA with a higher percentage of short (5-<10 min) and medium-to-long bouts (≥10min) had lower BMI%ile, and WC compared with children who accumulated MVPA with a lower percentage short and medium-to-long bouts.
    Preventive Medicine 01/2015; 73. DOI:10.1016/j.ypmed.2015.01.022 · 3.09 Impact Factor
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    • "Children were included in the study if they accumulated at least two weekdays and one weekend day with at least 10 h of wearing time. Age-dependant cut-offs (Freedson et al. 2005) were used to define moderate-tovigorous physical activity (MVPA), while SB was defined as an intensity of less than 100 counts per minute (cpm) (Trost et al. 2011). "
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    ABSTRACT: We evaluated whether regional differences in physical activity (PA) and sedentary behaviour (SB) existed along language boundaries within Switzerland and whether potential differences would be explained by socio-demographics or environmental characteristics. We combined data of 611 children aged 4 to 7 years from four regional studies. PA and SB were assessed by accelerometers. Information about the socio-demographic background was obtained by questionnaires. Objective neighbourhood attributes could be linked to home addresses. Multivariate regression models were used to test associations between PA and SB and socio-demographic characteristics and neighbourhood attributes. Children from the German compared to the French-speaking region were more physically active and less sedentary (by 10-15 %, p < 0.01). Although German-speaking children lived in a more favourable environment and a higher socioeconomic neighbourhood (differences p < 0.001), these characteristics did not explain the differences in PA behaviour between French and German speaking. Factors related to the language region, which might be culturally rooted were among the strongest correlates of PA and SB among Swiss children, independent of individual, social and environmental factors.
    International Journal of Public Health 01/2015; 60(3). DOI:10.1007/s00038-014-0645-8 · 2.70 Impact Factor
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