This article reports three studies that investigated psychometric properties of the Physical Activity Questionnaire for Older Children (PAQ-C). The PAQ-C is a guided self-administered 7-day recall measure designed to assess general physical activity levels during the school year for children in grades four and higher. Study one, with 215 students ranging in age from 9 to 15 yr, found the PAQ-C had acceptable item and test score characteristics such as item distribution, corrected item-total correlations, and internal consistency. Study two, involving 84 students ranging from 9 to 14 yr, indicated acceptable levels of test-retest reliability for both males (r = 0.75) and females (r = 0.82) after 1 wk. The third study used Generalizability theory to investigate the reliability for using the average of either two or three PAQ-C scores collected during fall, winter, and spring seasons. Based on the responses of 200 students ranging from 8 to 16 yr, generalizability coefficients exceeded 0.80 for either the average of two or three responses for both younger (<13 yr) and older subjects. In all three studies, the PAQ-C demonstrated acceptable internal consistency and males were significantly more active than females. These results provide preliminary support for the PAQ-C as a cost efficient method of assessing general levels of children's physical activity during the school year.

To investigate the influence of physical activity on bone mineral accrual during the adolescent years, we analyzed 6 years of data from 53 girls and 60 boys. Physical activity, dietary intakes, and anthropometry were measured every 6 months and dual-energy X-ray absorptiometry scans of the total body (TB), lumbar spine (LS), and proximal femur (Hologic 2000, array mode) were collected annually. Distance and velocity curves for height and bone mineral content (BMC) were fitted for each child at several skeletal sites using a cubic spline procedure, from which ages at peak height velocity (PHV) and peak BMC velocity (PBMCV) were identified. A mean age-and gender-specific standardized activity (Z) score was calculated for each subject based on multiple yearly activity assessments collected up until age of PHV. This score was used to identify active (top quartile), average (middle 2 quartiles), or inactive (bottom quartile) groups. Two-way analysis of covariance, with height and weight at PHV controlled for, demonstrated significant physical activity and gender main effects (but no interaction) for PBMCV, for BMC accrued for 2 years around peak velocity, and for BMC at 1 year post-PBMCV for the TB and femoral neck and for physical activity but not gender at the LS (all p < 0.05). Controlling for maturational and size differences between groups, we noted a 9% and 17% greater TB BMC for active boys and girls, respectively, over their inactive peers 1 year after the age of PBMCV. We also estimated that, on average, 26% of adult TB bone mineral was accrued during the 2 years around

Two studies assessed the validity of the Physical Activity Questionnaire for Older Children (PAQ-C), a 7-day recall that assesses general moderate to vigorous physical activity levels during the school year. The first study, involving 89 elementary school students in Grades 4-8, investigated convergent, divergent, and construct validity. The PAQ-C was moderately related to an activity rating (r = .63), week summation of 24-hs moderate to vigorous activity recalls (r = .53), a teacher's rating of physical activity (r = .45), and perceptions of athletic competence (r = .48). As expected, the PAQ-C was not related to perceptions of behavioral conduct. The second study, involving 97 elementary school students, investigated convergent and construct validity. The PAQ-C was moderately related to an activity rating (r = .57), the Leisure Time Exercise Questionnaire (r = .41), a Caltrac motion sensor (r = .39), a 7-day physical activity recall interview (r = .46), and a step test of fitness (r = .28). The PAQ-C validity coefficients were as high as or greater than the 7-day recall interview. These two studies support the validity of the PAQ-C as a method of assessing older children's general physical activity levels.The authors are with the College of Physical Education at the University of Saskatchewan, 105 Gymnasium Place, Saskatoon, SK Canada S7N OWO.Physical Activity Questionnaire for Older elationships with other physical activity measures can be used with children. These nethods include motion sensors (12,14,17), 7 -y self-reports of activity (6, lo), activity rating (21), 7-day recall interview (17,18,20), and teacher assessment (24).Construct validity evidence can be established by testing how well a physical activity measure is correlated with related constructs (27), such as cardiovascular health, muscular-skeletal health, participation in organized sport and games, and perceptions of athletic competence. These interrelationships have been found in empirical research or are theoretically proposed.Small sample sizes make it difficult or inappropriate to examine gender differences on physical activity measures (18). As a result, gender differences on most physical activity measures have often not been tested. Most findings have shown males to have higher activity levels across various age groups of youth (1,9,13,22), although there are exceptions (15,25). Study 1The first study examined the convergent and construct validity of the PAQ-C. The hypotheses of the first study were that the PAQ-C would be positively related to an activity rating (21), teacher's rating of physical activity (PA2; 24), and a daily

Bone area (BA) and bone mineral content (BMC) were measured from childhood to young adulthood at the total body (TB), lumbar spine (LS), total hip (TH), and femoral neck (FN). BA and BMC values were expressed as a percentage of young-adult values to determine if and when values reached a plateau. Data were aligned on biological ages [years from peak height velocity (PHV)] to control for maturity. TB BA increased significantly from À4 to þ4 years from PHV, with TB BMC reaching a plateau, on average, 2 years later at þ6 years from PHV (equates to 18 and 20 years of age in girls and boys, respectively). LS BA increased significantly from À4 years from PHV to þ3 years from PHV, whereas LS BMC increased until þ4 from PHV. FN BA increased between À4 and þ1 years from PHV, with FN BMC reaching a plateau, on average, 1 year later at þ2 years from PHV. In the circumpubertal years (À2 to þ2 years from PHV): 39% of the young-adult BMC was accrued at the TB in both males and females; 43% and 46% was accrued in males and females at the LS and TH, respectively; 33% (males and females) was accrued at the FN. In summary, we provide strong evidence that BA plateaus 1 to 2 years earlier than BMC. Depending on the skeletal site, peak bone mass occurs by the end of the second or early in the third decade of life. The data substantiate the importance of the circumpubertal years for accruing bone mineral. ß