How long should a person wait between eating and doing exercise?
It depends on what you’ve eaten, and how hard you’re going to exercise. The ‘standard’ advice to wait an hour was based on social habits; swimming used to be a serious public sport, and meals were pretty big. Digestion and activity both need quite a bit of blood supply, and your body hasn’t got enough blood in it to perform both of these tasks very intensively. So swimming hard, shortly after a meal, would divert blood from your digestive system. Because it couldn’t cope with the food you’d eaten, your system would vomit to get rid of it, or become explosively unhygenic at the other end. Neither of these outcomes is particularly welcome in a swimming pool. Nowadays, sport swimmers are an elite with their own clubs and training schedules, so a member of the public isn’t likely to be able to swim hard (‘aerobically’). Most swimming is ‘sub-aerobic’ (which makes it an excellent exercise), so it doesn’t demand a massive share of your blood supply. Meals are also less of a ‘family event’ th
