No effect of exercise on colon mucosal prostaglandin concentrations: A 12-month randomized controlled trial

Background: Epidemiologic studies provide evidence that exercise is associated with reduced risk of colon cancer. Exercise may exert protective effects on the colon by influencing prostaglandin production. We hypothesized that an exercise intervention would decrease prostaglandin E2 concentrations and increase prostaglandin F2 alpha in colon biopsies compared with controls. Methods: A 12-month randomized controlled trial testing the effects of exercise on colon mucosal prostaglandin concentrations was conducted in men (n = 95) and women (n = 89). The exercise intervention included moderate-to-vigorous aerobic activity, 60 min/d, 6 days/wk versus controls. Prostaglandin E2 and F2 alpha concentrations were measured in colon biopsies using an enzyme-linked immunoassay at baseline and at 12 months to assess changes in mean concentration for each group. Results: Baseline colon prostaglandin E2 and F2 alpha concentrations were not correlated with age, race, education, family history of colon cancer, previous polyps, body size, diet, smoking, nonsteroidal antiinflammatory drug use, metabolic factors, or sex hormone levels. For both men and women, the exercise and control groups showed no change in mean prostaglandin E2 or F2 alpha between the baseline and 12-month biopsies. There was no difference in mean prostaglandin concentrations between exercisers and controls when exercisers were grouped by level of intervention adherence. Results were not modified by baseline age, body mass index, percentage of body fat, nonsteroidal anti inflammatory drug use, history of adenomatous polyps, or family history of colon cancer. Conclusion: A 12-month moderate-to-vigorous intensity aerobic exercise intervention did not result in significant changes in colon mucosal prostaglandin concentrations.