Pedometer-determined physical activity and body composition in New Zealand children

The objectives of this study were to examine current levels of pedometer-determined physical activity in a multiethnic sample of New Zealand children and to investigate associations among weekday and weekend step counts, body mass index (BMI), waist circumference (WC), and percentage body fat (%BF).

A total of 1115 children (536 boys, 579 girls) aged 5-12 yr wore sealed multiday memory pedometers for three weekdays and two weekend days. The ethnic composition of the sample was 49.2% European, 30.0% Polynesian, and 16.5% Asian, with 4.3% from other ethnicities. BMI was determined from height and weight, and %BF was measured using hand-to-foot bioelectrical impedance analysis. Participants were classified as normal weight, overweight, or obese using international BMI cutoff points (4), and into normal or central fat distribution groups using national WC standards (28). The 90th percentile of %BF for each age and sex subgroup was used to identify normal and high body fatness.

Mean step counts for this sample were 16,133 +/- 3,864 (boys) and 14,124 +/- 3,286 (girls) on weekdays, and 12,702 +/- 5,048 (boys) and 11,158 +/- 4,309 (girls) on weekends. Significant differences in step counts were observed between weekdays and weekends, boys and girls, and among age, ethnic, and socioeconomic groups. Analysis of variance revealed stronger associations between step counts and %BF category than between step counts and BMI or WC groups.

This study provides evidence of a link between daily step counts and body fatness in children. Our results also suggest that the promotion of physical activity during the weekend is a key priority for young New Zealanders.