I once took a class on playing for dancing with Jim Johnstone. One of his tips: don't program the Dashing White Sergeant if your dancers are elderly. It doesn't have any moments for people to stand still and get their breath back, so its cardiovascular demands are unusually high.

A friend of mine once played for a ceilidh that was mostly elderly foreign tourists. One of them was very insistent about getting an encore dance at the end of the programme. So they did one, and the requester keeled over and died instantly of a heart attack while doing it.