walking after lunch/dinner

Question
There is a saying as per our tradition (Indian) that one should walk a  mile after dinner to help digestion. Is it healthy to have a walk after lunch/dinner? Many medical experts claim that since the stomach will require a lot of blood for digestion after partaking food, one should not expose himself to physical strain like walking since the legs will then compete for the blood flow impeding the digestion? Which school of thought is correct?

Answer
Your question is a good one, and the answer is: it depends.

A stroll after a meal should not inhibit digestion as long as the walking is slow enough and short enough -- no sweating, hard breathing or long distances. My personal experience is that as long as the exercise is leisurely enough, it does help digestion. I just have not seen any studies to prove this.

Exercise only interferes with digestion when the intensity and/or the duration become too great. This is why runners in high-intensity races must eat their last big meal at least four hours prior to the race. You might think that the food bouncing around in the stomach would be uncomfortable, and it is. However, lack of blood available for digestion also slows the digestion and keeps the food churning far longer in the stomach, thus extending the discomfort.

In my ultramarathon races, the exercise intensity is much lower, but the races go on for hours and sometimes days. That means we must eat during the race, and that leads sometimes to discomfort from the same cause. The muscles are hoarding the blood flow, making digestion difficult.