A question! [swimming on a full belly]

[desperance]

Is there any truth in the rumour that swimming after a full meal can cause stomach cramps or other undesirable symptoms? When I was a kid, this was so much believed that we weren't even allowed to take a bath too soon after eating. I can state categorically that this was an exaggerated anxiety - but does some actuality underlie it? And would people have known about it/been similarly anxious in the long-ago? (Say eighteenth-century, for a more-or-less touchstone.)