I'm 4.1 .73 years old I work weights 3 times and wal2 miles a day .cardiologist advised light weights ( I probably use more than I should). I was sort in a daze when I talk to him a bit taken back. But I do know I go on treadmill and walk faster the 3.6mph my bpm goes above 130 bpm.
From what I get from this site that is not good. So I can just imagine what it would be if I played tennis. Which I do enjoy.