. Author manuscript; available in PMC: 2012 Aug 1.

Published in final edited form as: Arch Pediatr Adolesc Med. 2011 Apr 4;165(8):723–728. doi: 10.1001/archpediatrics.2011.34

Table 1.

Baseline demographics and lifestyle characteristics of 6831 preadolescent, adolescent, and young adult females in the Growing Up Today Study

Mean (S.D.) age (years)	12.0 (1.6)
Mean (SD) body mass index (kg/m²)	19.0 (3.3)
Mean (SD) age at menarche (years)	11.8 (1.0)
% Post-menarcheal	44.1% (n=3008)
% Underweight	8.6% (n=570)
% Overweight or obese	19.8% (n=1309)
% Disordered eating	2.5% (n=169)
% Maternal history of low bone density or osteoporosis	10.4% (n=707)
Hours per week of moderate or vigorous activity^a
< 1 hour/week	0.2% (n=12)
1–3.9 hrs/wk	3.4% (n=222)
4–7.9 hrs/wk	14.0% (n=918)
8–11.9 hrs/wk	19.9% (n=1310)
12–15.9 hrs/wk	18.8% (n=1239)
16–19.9 hrs/wk	15.0% (n=988)
20–24.9 hrs/wk	11.2% (n=734)
> 25 hrs	15.7% (n=1033)
Mean (SD) hours/week of non impact activity	4.7 (3.3)
Mean (SD) hours/week of intermediate impact activity	2.2 (2.4)
Mean (SD) hours/week of high impact activity^b	5.2 (4.1)

Sum of basketball, baseball, biking, dance/aerobics, hockey, running, swimming, skating, skateboarding, soccer, tennis, cheerleading, lifting weights, volleyball, and karate.

Sum of basketball, running, soccer, tennis, cheerleading, and volleyball.