title: Biological age and habitual physical activity in relation to physical fitness in 12- and 13-year-old schoolboys.
abstract: OBJECTIVE
  The purpose of this study was to investigate the relationship between biological age, habitual physical activity and anthropometrical and physiological characteristics in 12- and 13-year-old schoolboys (n = 70).
  
  
  METHODS
  At the beginning and the end of the school year 1971/2 biological age was determined by measuring skeletal age from left hand X-ray photographs. Habitual physical activity was determined by questionnaire interview and pedometers.
  
  
  RESULTS
  All anthropometrical characteristics showed significant correlations (P less than 0.05) with skeletal age except for bicipital and tricipital skinfolds. Out of 9 physical fitness tests handgrip was the only test that showed a significant correlation (0.52) with skeletal age. Pedometer scores gave significant negative correlations (P less than 0.05) with anthropometrical characteristics except for tricipital skinfold. The fitness tests bent arm hang, 12 min run walk, sit and reach and W-170 showed significant correlations (P less than 0.05) with pedometer scores.
mesh_terms: D000203:Activities of Daily Living; D000365:Age Determination by Skeleton; D000367:Age Factors; D000886:Anthropometry; D001824:Body Constitution; D006225:Hand / Q000000981:diagnostic imaging; D008124:Locomotion; D009426:Netherlands; D005082:Physical Exertion; D010809:Physical Fitness; D011627:Puberty; D012572:School Health Services; D013147:Spirometry; D011795:Surveys and Questionnaires