We have been discussing the negative effects (and symptoms) of exercise on the digestive system. Now let's take a look at the benefits of exercise - disease prevention and rehabilitation in those with pre existing chronic GI diseases. (For those of you not familiar with the term relative risk (RR), it indicates your risk of the disease state compared to someone that does not exercise regularly. For example, if your RR is 0.5, you have 1/2 the chance of being affected. If it is 0.33, 1/3 - and so on.

I. There is clear proof of:

• protection from colon cancer - 3rd leading cancer in the US
  • a protective effect at all exercise levels - recreational on up
  • but "exercisers" also smoke less, are thinner (a risk factor), etc. and in general eat higher fiber diets
  • RR of 0.5 in studies controlling for risk factors other than exercise - it is an independent variable and additive to others.
  • it has been speculated (and unproven) this may be due to a decrease in transit time and thus less contact time for carcinogens with the colon mucosa.
• a decrease in cholelithiasis
  • 30 minutes of aerobic activity 5 times a week) lowers the relative risk = 0.66
  • independent of other variables such as obesity
• a decreased risk of duodenal ulcer disease
  • adjusted for life style (smoking, alcohol, self reported tension), moderate exercise had a RR of 0.38, while higher was 0.54 (this may be a good example of more being less)
• a decrease in gross, large volume, rectal bleeding in seniors
  • recreational activity significantly decreases the risk of overt bleeding in seniors (>68 yo - 8000 followed for 3 years)
• a decrease in symptomatic diverticular disease
  • 47000 men followed over 4 years
  • after controlling for fiber in diet, age, and fat intake
  • reduced risk associated with activity - more vigorous, less incidence
  • vigorous defined as running a 10 min mile), jogging (<10 min mile), cycling
  • RR was 0.53 for vigorous

• a decrease in constipation
  • There is an association with inactivity in older individuals BUT it is unproven that an Rx for exercise will be helpful.
  • a controlled trial in 8 women (<50 y/o) with chronic idiopathic constipation could demonstrate no benefit of 4 weeks of regular activity
  • No clear association of constipation with inactivity in younger, otherwise healthy patients.
  • active people tend to eat higher fiber diets - a confounding variable
• Inflammatory Bowel Disease. Unproven, but not harmful! Need to individualize the program.
  • exercise can retard osteopenia and osteoporosis - not the preferred treatment
  • over all sense of well being is better (proven)
  • symptoms/disease no more active with moderate exercise
  • a retrospective study (memory error possible) shoed a RR of 0.5, even with minimal levels of activity
• Irritable Bowel Syndrome - one study of runners demonstrated a prevalence of IBS symptoms (constipation, abd pain, gas) in ~25% before running and a significant decrease in symptoms after they started running
• Liver disease - no negative effect, and increases overall sense of well being and thus rehabilitation with chronic disease (such as Hepatitis C).