Article

Comparison of two sets of accelerometer cut-off points for calculating moderate-to-vigorous physical activity in young children

Child Obesity Research Centre, Faculty of Education, University of Wollongong, NSW 2522, Australia.
Journal of physical activity & health (Impact Factor: 1.95). 11/2007; 4(4):509-13.
Source: PubMed
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    • "This indicates that studies investigating relationships between activity and these health outcomes may be comparable, even where different thresholds have been employed. However, as in previous research (Cliff and Okely, 2007; Guinhouya et al., 2006), this study has demonstrated that intensity thresholds clearly matter when reporting the percentage of children meeting MVPA guidelines. Therefore, despite the lack of impact of threshold on relationships between these health outcomes and activity, to enable comparability between activity prevalence studies a consensus on the thresholds to be used is needed. "
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    ABSTRACT: It is unknown whether relationships detected between physical activity intensity and health differ according to accelerometer thresholds used [sample-specific thresholds (SSTs), published thresholds (PTs) or the individualized activity-related time equivalent (ArteACC)]. SSTs were developed through ActiGraph calibration in 52 boys, aged 8-10 years. The boys subsequently wore an ActiGraph for seven days. SSTs, PTs and ArteACC for moderate (MPA) and vigorous (VPA) activity were applied. Waist circumference (WC), peak oxygen consumption (VO2peak) and blood pressure were assessed. After applying SSTs, 48.9% of boys achieved 60+ minutes of daily MVPA, compared with 8.5% with PTs and 100% with ArteACC. MPA and VPA were correlated with WC and VO2peak, regardless of whether PTs or SSTs were used (WC: MPA r = -0.37 to -0.43; VO2peak: r = 0.34 to 0.39, p < 0.05). With ArteACC, only VPA was correlated with WC (r = -0.39, p < 0.01) and VO2peak (r = 0.35, p < 0.05). Relationships with blood pressure were statistically non-significant. Although estimates of the quantity of activity differed according to thresholds used, relationships detected with health were consistent regardless of whether SSTs or PTs were employed. There was no advantage of using SSTs or individualized thresholds. Researchers are encouraged to use PTs to ensure greater comparability between studies. Key pointsStandardized accelerometer intensity thresholds for evaluating children's physical activity do not exist, therefore determining whether relationships between activity and health differ when using different thresholds is of interest.Although prevalence estimates differ according to the choice of accelerometer intensity threshold, relationships detected between activity and various health outcomes in boys are similar, providing the moderate threshold is at least equivalent to an average brisk walk (i.e., ≥ 4 METs).Standardization of thresholds between samples should not impact on relationships determined with health and would allow comparability of prevalence estimates.
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    ABSTRACT: Accurate physical activity quantification in preschoolers is essential to establish physical activity prevalence, dose-response relationships between activity and health outcomes, and intervention effectiveness. To date, best practice approaches for physical activity measurement in preschool-aged children have been relatively understudied. This article provides a review of physical activity measurement tools for preschoolers, an overview of measurement of preschoolers' physical activity, and directions for further research. Electronic and manual literature searches were used to identify 49 studies that measured young children's physical activity, and 32 studies that assessed the validity and/or reliability of physical activity measures with preschool-aged children. While no prevalence data exist, measurement studies indicate that preschool children exhibit low levels of vigorous activity and high levels of inactivity, boys are more active than girls, and activity patterns tend to be sporadic and omnidirectional. As such, measures capable of capturing differing activity intensities in very short timeframes and over multiple planes are likely to have the most utility with this population. Accelerometers are well suited for this purpose, and a number of models have been used to objectively quantify preschoolers' physical activity. Only one model of pedometer has been investigated for validity with preschool-aged children, showing equivocal results. Direct observation of physical activity can provide detailed contextual information on preschoolers' physical activity, but is subjective and impractical for understanding daily physical activity. Proxy-report questionnaires are unlikely to be useful for determining actual physical activity levels of young children, and instead may be useful for identifying potential correlates of activity. Establishing validity is challenging due to the absence of a precise physical activity measure, or 'criterion', for young children. Both energy expenditure (EE) and direct observation have been considered criterion measures in the literature; however, EE is influenced by multiple variables, so its use as a physical activity 'criterion' is not ideal. Also, direct observation is inherently subjective, and coding protocols may result in failure to capture intermittent activity, thereby limiting its utility as a physical activity criterion. Accordingly, these issues must be taken into account where EE or direct observation are used to validate physical activity instruments. A combination of objective monitoring and direct observation may provide the best standard for the assessment of physical activity measurement tools. Ideally, the convergent validity of various physical activity tools should be investigated to determine the level of agreement between currently available measures. The correlational approaches commonly employed in the assessment of physical activity measures do not reveal this relationship, and can conceal potential bias of either measure.
    Sports Medicine 02/2007; 37(12):1045-70. · 5.32 Impact Factor
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    ABSTRACT: Accurate physical activity quantification in preschoolers is essential to establish physical activity prevalence, dose-response relationships between activity and health outcomes, and intervention effectiveness. To date, best practice approaches for physical activity measurement in preschool-aged children have been relatively understudied. This article provides a review of physical activity measurement tools for preschoolers, an overview of measurement of preschoolers’ physical activity, and directions for further research. Electronic and manual literature searches were used to identify 49 studies that measured young children’s physical activity, and 32 studies that assessed the validity and/or reliability of physical activity measures with preschool-aged children. While no prevalence data exist, measurement studies indicate that preschool children exhibit low levels of vigorous activity and high levels of inactivity, boys are more active than girls, and activity patterns tend to be sporadic and omnidirectional. As such, measures capable of capturing differing activity intensities in very short timeframes and over multiple planes are likely to have the most utility with this population. Accelerometers are well suited for this purpose, and a number of models have been used to objectively quantify preschoolers’ physical activity. Only one model of pedometer has been investigated for validity with preschool-aged children, showing equivocal results. Direct observation of physical activity can provide detailed contextual information on preschoolers’ physical activity, but is subjective and impractical for understanding daily physical activity. Proxy-report questionnaires are unlikely to be useful for determining actual physical activity levels of young children, and instead may be useful for identifying potential correlates of activity. Establishing validity is challenging due to the absence of a precise physical activity measure, or ‘criterion’, for young children. Both energy expenditure (EE) and direct observation have been considered criterion measures in the literature; however, EE is influenced by multiple variables, so its use as a physical activity ‘criterion’ is not ideal. Also, direct observation is inherently subjective, and coding protocols may result in failure to capture intermittent activity, thereby limiting its utility as a physical activity criterion. Accordingly, these issues must be taken into account where EE or direct observation are used to validate physical activity instruments. A combination of objective monitoring and direct observation may provide the best standard for the assessment of physical activity measurement tools. Ideally, the convergent validity of various physical activity tools should be investigated to determine the level of agreement between currently available measures. The correlational approaches commonly employed in the assessment of physical activity measures do not reveal this relationship, and can conceal potential bias of either measure.
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