Table 1.

Baseline characteristics according to quintiles of total physical activity in 32,269 women in the Breast Cancer Detection Demonstration Project (BCDDP)*

Characteristic	Quintile of total physical activity
	1	2	3	4	5
Participants (n)	6453	6454	6441	6472	6449
Age (years)	61.7	61.1	61.3	60.8	61.0
MET-hours/week (range) †	105 to 244	245 to 297	298 to 339	340 to 394	395 to 721
Vigorous physical activity (hours/week)	0.9	3.6	5.4	10.3	22.7
Non-vigorous physical activity (hours/week)	14.8	32.4	46.5	54.5	59.7
Body mass index (kg/m2)	25.4	25.0	24.9	24.7	24.6
Height (inches)	64.3	64.2	64.2	64.2	64.1
Ever smoked cigarettes (%)	46.9	44.6	43.4	42.1	40.7
Education (% more than high school)	55.0	50.0	46.8	46.1	42.0
Age at first birth (years) ‡	24.0	23.9	23.8	23.9	23.5
Parity (number of births) ‡	2.8	2.8	2.9	2.9	3.0
Age at menarche (years)	12.7	12.7	12.8	12.8	12.9
Age at menopause (years)	50.4	50.3	50.2	50.4	50.3
History of oral contraceptive use (%)	33.8	33.2	33.4	32.8	31.1
Current menopausal hormone therapy (%)	55.3	54.7	55.8	55.7	54.1
Family history of breast cancer (%) ¶	34.0	35.1	34.1	34.4	33.6
History of benign breast disease (%) §	55.5	56.0	55.4	55.6	55.2
Total energy intake (kcal/day)	1252	1256	1266	1271	1277
Dietary fat intake (g/day) ||	46.9	46.5	46.3	46.0	45.9
Alcohol intake (g/day)	4.5	4.4	4.1	4.0	3.6

* All values (except age and range of MET-hours/week) are directly standardised to the age distribution of the cohort at study baseline.

† MET = metabolic equivalent task. The MET value is the caloric need per kilogram of body weight per hour of activity divided by the caloric need per kilogram of body weight per hour at rest.

‡ Among parous women only.

¶Family history of breast cancer includes first- and second-degree relatives with a history breast cancer.

§The BCDDP Follow-up Study includes a disproportionate number of women with benign breast disease due to the design of the original BCDDP.

||Adjusted for total energy intake.