Proper exercise can reverse damage from heart aging. Exercise can reverse damage to sedentary, aging hearts and help prevent risk of future heart failure -- if it's enough exercise, and if it's begun in time, according to a new study by cardiologists. Source 1t.
Maybe this is why you might see someone at 70 that's bed ridden and another that's 70 in the gym. Only difference is one of the 70 year old's didn't let age keep her back.
I plan to be in my 70s and still going strong so I do some exercising as I can. I know at times being disabled I can have a hard time doing what I want but other times I can. I still plant to be around to the ripe age of 129. SO I guess exercising is a must.
The best kind of exercise to go into your older years is cardiovascular. It does not have to be very strenuous either: some brisk walking, hiking or swimming.