Question

As does the same exercises on a regular basis, they may find that their heart rate decreases with the same amount of activity, this is because
The muscles have acclimated to the work so now it's not as much work

The heart muscle has become stronger and can pump more blood and oxygen per beat

Both A & B

None of the Above

Answer 1

I would say both A & B, being a bodybuilder myself I've learned this through experience. The muscles will gradually grow and the heart will become stronger also, since the heart is indeed a muscle.