Issn Print: 0195-9131

Publication Date: 2001/05/01


Print

ASSESSING PHYSICAL ACTIVITY AMONG CHILDREN WITH ACTIVITY MONITORS USING DIFFERENT TIME SAMPLING INTERVALS AND PLACEMENTS

A Nilsson; U Ekelund; A Yngve; M Sjöström

+ Author Information

Author Information: Unit for Preventive Nutrition, Department of Medical Nutrition, Karolinska Institute, Stockholm, Sweden. Department of Physical Education and Health, Örebro University, Örebro, Sweden

    loading  Checking for direct PDF access through Ovid

Excerpt

This study investigated the effect of a) different time sampling intervals (epochs) when measuring physical activity with the Computer Science and Application's Inc. (CSA) activity monitor, and b) different placement of the monitor. Sixteen children, 7 years old, wore two monitors for four days, one attached on the right hip and the other on the low back. The epoch was set to every 5 seconds and later reintegrated into 10-, 20-, 40- and 60-seconds epochs. Averaged activity counts (cntsmin-1), time spent at three different intensity levels using published cut-off values (Freedson et al, MSSE, 30: 777–81, 1998), and number of consecutive ten-minute periods where activity counts exceeded the level of moderate intensity was calculated. A multivariate analysis of variance revealed a main significant epoch effect for time spent at high (p < .01) and very high (p < .01) intensities, while no significant difference was observed for time spent at moderate intensity. There was a significant epoch effect for number of consecutive ten-minute periods between the 60 seconds measurement and all other epoch settings. No significant difference in cntsmin-1 was found between the two different body placements and neither for time spent at different intensity levels except for time spent at moderate intensity when measured with the 5-seconds epoch setting (p < .01). It was concluded that longer time sampling intervals (e.g. 60 seconds) make shorter episodes of high intensity activity to remain undetected when examining intensity patterns. This circumstance, but not body placement, should be carefully considered when data outcome is interpreted and reported.
    loading  Loading Related Articles