Characteristics of postmenopausal women included in the analysis from the UK Biobank
| Characteristics | N=17 840 |
| Follow-up time (years), median (min, max) | 11.0 (>0.0 to 12.2) |
| Age (years), median (IQR) | 60 (56–64) |
| Age categories, n (%) | |
| 40 to <50 | 869 (4.9) |
| 50 to <60 | 6886 (38.6) |
| 60 t o<70 | 10 002 (56.1) |
| >70 years | 81 (0.5) |
| BMI (kg/m2), median (IQR) | 25.9 (23.4–29.1) |
| BMI categories, n (%) | |
| Underweight/normal weight | 7332 (41.1) |
| Overweight | 6892 (38.6) |
| Obesity | 3616 (20.3) |
| Body fat percentage, median (IQR) | 36.8 (32.2–41.2) |
| Body fat percentage categories | |
| First quintile (<20th percentile) | 3591 (20.1) |
| Second quintile (>20th to 40th percentile) | 3569 (20.0) |
| Third quintile (>40th to 60th percentile) | 3497 (19.6) |
| Fourth quintile (>60th to 80th percentile) | 3632 (20.4) |
| Fifth quintile (>80th percentile) | 3551 (19.9) |
| Ethnicity, n (%) | |
| White | 16 502 (92.5) |
| Black | 387 (2.2) |
| Other* | 951 (5.3) |
| Education, n (%) | |
| Less than postsecondary† | 4498 (25.2) |
| Postsecondary‡ | 10 702 (60.0) |
| Missing§ | 2640 (14.8) |
| Family history of breast cancer (Yes)¶, n (%) | 2064 (11.6) |
| Age at menarche (years), median (IQR) | 13.0 (12.0–14.0) |
| Parous (yes), n (%) | 14 416 (80.8) |
| No of live births, median (IQR) | 2 (1–2) |
| No of live births category, n (%) | |
| Nulliparous | 3424 (19.2) |
| One | 2274 (12.8) |
| Two | 8048 (45.1) |
| Three or more | 4094 (23.0) |
| Age at first birth** (years), n (%) | |
| <20 | 1050 (8.7) |
| 20 to <25 | 3833 (31.6) |
| 25 to <30 | 4868 (40.1) |
| 30 to <35 | 1915 (15.8) |
| >35 | 462 (3.8) |
| Hormone replacement therapy use, n (%) | 381 (2.1) |
| Smoking status, n (%) | |
| Never | 7789 (43.7) |
| Current | 1177 (6.6) |
| Previous | 8874 (49.7) |
| Alcohol frequency, n (%) | |
| Never | 1572 (8.8) |
| Special occasions only | 2.683 (15.0) |
| 1–3 times a month | 2175 (12.2) |
| Once or twice a week | 4306 (24.1) |
| 3 or 4 times a week | 3833 (21.5) |
| Daily | 3271 (18.3) |
| MET-minutes per week††, median (IQR) | 1879.5 (924.0–3666.0) |
| Protocol | |
| 1 (minimal risk)‡‡ | 15 147 (84.9) |
| 2 (small risk)§§ | 2064 (11.6) |
| 3 (medium risk)¶¶ | 629 (3.5) |
| Exposure | |
| VO2peak (mL/kg/min), mean±SD | 20.5±2.1 |
| eCRF level, n (%) | |
| Low eCRF | 3566 (20.0) |
| Moderate eCRF | 10.704 (60.0) |
| High eCRF | 3570 (20.0) |
| Outcome | |
| Breast cancer, n (%) | 529 (3.0) |
| Other cancer, n (%) | 1623 (9.1) |
| Death, n (%) | 241 (1.4) |
*Asian, mixed, other and missing.
†Advanced levels, advanced subsidiary levels or equivalent; ordinary levels, general certificate of secondary education or equivalent; certificate of secondary education or equivalent.
‡College or university; national vocational qualification, higher national diploma, higher national certificate or equivalent; other professional qualification (eg, teacher, nurse)
§None of the above or missing.
¶Self-reported history of their father, mother, sister and/or brother having had breast cancer.
**N=22 396.
††Three types of physical activity were self reported using a modified version of the IPAQ short form: walking, moderate and vigorous physical activity. Data were cleaned using standardised procedures, and then minutes of physical activity were multiplied by corresponding MET values for walking (3.3 METs), moderate (4.0 METs) and vigorous (8.0 METs) physical activity to determine total weekly METs of physical activity.
‡‡Participants who complete protocol 1 (aka minimal risk) for the eCRF assessment work at a maximum of 50% of their predicted workload.
§§Participants who complete protocol 2 (aka small risk) for the eCRF assessment work at a maximum of 35% of their predicted workload.
¶¶Participants who complete protocol 3 (aka medium risk) for the eCRF assessment worked at a constant workload.
%, per cent; BMI, body mass index; eCRF, estimate cardiorespiratory fitness; IQR, interquartile range; max, maximum; MET, metabolic task equivalent; min, minimum; n, sample size; SD, standard deviation.