I tend to believe that a heart is like a battery and has only so many beats to it before it's game over.
Slow and easy, conserving heart beats.... could this be the reason why a tortoise can live such a long time?
The average number of beats per minute in a non "athlete's heart" is 70 beats.
With the proper diet, and no exercise - would a couch potato outlive a person who jogs and eats the same diet?
Take two laboratory mice, feed them the same diet.... put an exercise wheel in each cage... one that is super lubed and will allow the mouse to run like crazy, and an exercise wheel in the other cage that only allows the mouse to walk - not run.
Which will live longer? The running mouse or the walking mouse?
For dogs weighing 30 lbs. or less, the average heart rate is 100 to 160 beats per minute. For dogs weighing more than 30 lbs., the average heart rate is 60 to 100 beats per minute. A cat has an average heart rate of 160 to 220 beats per minute.