Table 2.

Risk of colorectal polyps in relation to hours per week of vigorous exercise, hours per week of walking, and MET-hours/wk of vigorous exercise and walking in the BWHS

Hours/wk of vigorous exercise
None<11-23-45-6≥7
Cases875181173883934
Person-years139,73351,07044,43728,16312,35511,271
Age-adjusted IRR (95% CI)1.00 (Reference)0.80 (0.68-0.94)0.92 (0.78-1.08)0.74 (0.60-0.93)0.81 (0.59-1.11)0.77 (0.55-1.09)
Multivariate IRR* (95% CI)1.00 (Reference)0.81 (0.69-0.96)0.95 (0.80-1.12)0.77 (0.62-0.97)0.87 (0.63-1.20)0.85 (0.60-1.21)
Hours/wk of walking
None
<1
1-2
3-4
5-6
≥7
Cases153230496235108168
Person-years27,83744,170101,48447,45025,59440,494
Age-adjusted IRR (95% CI)1.00 (Reference)0.99 (0.81-1.22)0.96 (0.80-1.15)0.94 (0.77-1.15)0.78 (0.61-1.00)0.79 (0.63-0.98)
Multivariate IRR (95% CI)1.00 (Reference)1.00 (0.82-1.23)1.00 (0.83-1.20)0.99 (0.81-1.22)0.82 (0.63-1.05)0.85 (0.68-1.06)
MET-h/wk of vigorous exercise and walking
None
<5
5-9
10-19
20-39
≥40
Cases132288273325229143
Person-years20,79349,47553,54164,70655,24243,272
Age-adjusted IRR (95% CI)1.00 (Reference)0.93 (0.76-1.15)0.89 (0.72-1.10)0.90 (0.74-1.10)0.82 (0.66-1.01)0.70 (0.55-0.88)
Multivariate IRR (95% CI)1.00 (Reference)0.94 (0.76-1.15)0.91 (0.74-1.12)0.91 (0.74-1.12)0.83 (0.67-1.03)0.72 (0.57-0.91)
  • * Adjusted for age, BMI, smoking, family history of colorectal cancer, education, and total hours of walking.

  • Adjusted for age, BMI, smoking, family history of colorectal cancer, education, and hours of vigorous exercise.

  • Adjusted for age, BMI, smoking, family history of colorectal cancer, and education.