Table 1.

Baseline characteristics of randomized WISER participants (n = 318)

Exercisers (n = 165)Controls (n = 153)
Demographics
 Age, y (mean ± SE)25.4 ± 0.325.2 ± 0.3
 Not married or partnered, n (%)137 (83%)124 (81%)
 Education beyond high school, n (%)157 (95.2%)148 (96.7%)
 Caucasian, n (%)123 (75%)107 (70%)
Body composition (mean ± SE)
 Weight, kg67.5 ± 1.167.6 ± 1.2
 BMI, kg/m224.8 ± 0.424.7 ± 0.4
 % body fat36.4 ± 0.736.1 ± 0.7
 Fat mass, kg24.3 ± 0.924.1 ± 0.9
 Lean mass, kg39.8 ± 0.440.1 ± 0.4
Reproductive characteristics
 Age at menarche, y (mean ± SE)a12.7 ± 0.1212.7 ± 0.11
 Nulliparous, n (%)153 (93%)144 (94%)
 Previous contraceptive use, n (%)84 (51%)82 (54%)
Family history of breast cancerb
 No, n (%)129 (96%)114 (97%)
Physical activity, fitness, and diet (mean ± SE)
 Moderate exercise (MET-h/wk)1902 ± 4211933 ± 525
 Aerobic fitness (METs at 85% max HR)21.9 ± 1.321.8 ± 1.4
 Total calorie intake,c kcal/d6.9 ± 0.17.1 ± 0.1

NOTE: There were no significant differences at baseline between study groups for any of these variables.