title: Comparison of physical activity in male and female children: does maturation matter?
abstract: OBJECTIVE
  To investigate whether observed differences in physical activity levels in boys and girls are confounded by biological age differences particularly during the circumpubertal years.
  
  
  METHODS
  The physical activity questionnaire for children (PAQ-C) was administered biannually or triannually to 138 (70 boys; 68 girls) Canadian children for seven consecutive years from 1991 to 1997. Participants were 9-18 yr of age. Anthropometric measurements were taken biannually and age at peak height velocity (PHV) determined. Biological age was defined as years from PHV. The data were analyzed using t-tests and random effects models.
  
  
  RESULTS
  Level of physical activity decreased with increasing chronological age in both sexes. When aligned on chronological age bands, boys had statistically significantly higher PAQ-C summary scores than girls from 10 through 16 yr of age (P < 0.05). However, when aligned on biological age, sex differences were not apparent, except at 3 yr before PHV. Random effects models of individual growth patterns confirmed these findings.
  
  
  CONCLUSIONS
  Physical activity decreased with increasing chronological age in boys and girls. There were no sex differences in the longitudinal pattern of physical activity when the confounding effects of biological age were controlled except at 3 yr before PHV.
authors.affiliation: Department of Human Kinetics, St. Francis Xavier University, PO Box 5000, Antigonish, Nova Scotia, Canada B2G 2W5. amthomps@stfx.ca
authors.forename: Angela  M
authors.initials: A
authors.lastname: Thompson
authors.forename: Adam D G
authors.initials: AD
authors.lastname: Baxter-Jones
authors.forename: Robert L
authors.initials: RL
authors.lastname: Mirwald
authors.forename: Donald A
authors.initials: DA
authors.lastname: Bailey
mesh_terms: D000293:Adolescent; D000375:Aging / Q000502:physiology*; D000886:Anthropometry; D002648:Child; D002657:Child Development; D015444:Exercise; D005260:Female; D006801:Humans; D008297:Male; D011627:Puberty; D012727:Sex Characteristics; D011795:Surveys and Questionnaires