I never had any big issues but everyone is different. just a slightly sore arm for a day or two.

HOWEVER a doctor would probably give you a medical waiver as you are over sixty. Basically it is up to the immigration officer if they will take a medical waiver and Regent has to cover themselves to warn this could happen. Personally I highly doubt that the immigration officer will stop those with a medical waiver from going ashore. Particularly from a American cruise ship. They seem to barely glance at documents on a ship. But your call!