PA correlates/determinants were relatively consistent between objective and subjective PA measures .
A small number of demographic/biological and social/cultural factors were associated with PA .
CONTEXT Being physically active during the early years ( age 0 - 6 years ) is vital for healthy development .
Identifying correlates and determinants of physical activity ( PA ) is crucial to guide effective interventions .
This systematic review synthesized studies investigating potential correlates and determinants of PA during the early years , accounting for different types of PA assessment .
Spectral and bout detection analysis of physical activity patterns in healthy, prepubertal boys and girls
Little is known about the frequency‐intensity patterns of naturally occurring physical activity in children . A data set obtained previously by direct observation of  physical activity in 8 girls and 7 boys ( all prepubertal , ages 6–10 ) was analyzed with spectral analysis to detect significant frequency‐intensity relationships . Pulse detection algorithms were used to characterize the number of exercise bouts , their duration and relative intensity . Spectral analysis revealed that physical activity bouts were frequent , pulsatile , and r and om with no significant frequencies detected during many 24‐min periods of observation . An average of 83 ± 11 bouts per hour were observed in boys and 89 ± 12 bouts per hour in girls , and the mean duration of an exercise bout was 21 ± 5 sec for boys and 20 ± 4 sec for girls ( NS ) . While high‐intensity exercise bouts comprised less than 20 % of the time spent in physical activity , duration of high intensity exercise bouts tended to be longer and accounted for about 40 % of the energy expenditure associated with physical activity . Spontaneous physical activity in prepubertal children is characterized by frequent bouts of brief , mostly low intensity exercise , r and omly interspersed with less frequent , but metabolically substantial high intensity bouts . These findings are potentially useful in assessing the impact of disease on quality of life in children , investigating the relationship between physical activity and mechanisms of growth and development , and creating new approaches for in‐laboratory exercise testing in children . Am . J. Hum . Biol . 10:289–297 , 1998 . © 1998 Wiley‐Liss ,
PA correlates/determinants were relatively consistent between objective and subjective PA measures .
A small number of demographic/biological and social/cultural factors were associated with PA .
CONTEXT Being physically active during the early years ( age 0 - 6 years ) is vital for healthy development .
Identifying correlates and determinants of physical activity ( PA ) is crucial to guide effective interventions .
This systematic review synthesized studies investigating potential correlates and determinants of PA during the early years , accounting for different types of PA assessment .