The association between recreational physical activity, sedentary time, and colorectal polyps in a population screened for colorectal cancer

Purpose: Regular recreational moderate to vigorous physical activity (rMVPA) has been previously associated with a reduced risk of colorectal cancer (CRC), however, few studies have examined the association of rMVPA with colorectal polyps, the pre-malignant precursor lesions. The objective of this study was to examine the associations between physical activity and sitting time and polyps at the time of screening. Methods: We conducted a cross-sectional study of 2496 individuals undergoing screening-related colonoscopy in Calgary, Alberta, Canada. Physical activity and sitting time were characterized using hours of rMVPA, meeting physical activity recommendations and hours of sitting time using self-reported data obtained from the International Physical Activity Questionnaire. Logistic regression models were used to estimate the crude and adjusted odds ratios (OR) for presence of polyps associated with rMVPA and sitting time. Results: Meeting physical activity guidelines of >= 150 min/week was non-significantly associated with a modest decrease in odds of having >= 1 polyp at screening (ORadj= 0.95, 95% CI: 0.80-1.14). In males, threshold effects for sitting time were observed for up to 20 h/week (ORadj per hour sitting= 1.07, 95% CI: 1.01-1.13). In stratified analysis, larger inverse associations were observed between physical activity and the presence of polyps in females, obese individuals, and ever smokers, compared to pooled findings. Conclusions: In this large CRC screening population, there was a suggestive association between increased rMVPA and reduced prevalence of polyps at screening, particularly among females. Even low amounts of regular sitting time (0-20 h/day) were associated with the presence of polyps, particularly among males. Further research on rMVPA and sitting time is necessary to better inform strategies to reduce the frequency of pre-malignant colorectal lesions.