50 beats a minute when I was resting...was a sign of health.

Second the motion. Provided it comes from being well-conditioned rather than from other, pathological, causes. It's a highly positive survival trait. Think of it in athletes' terms: when you want to increas;e your activity your body needs to supply the tissues with more oxygen-carrying blood. That's known as "increasing the cardiac output," which is generally good (up to a point). There are only two ways to do it: make each stroke bigger, or make more of them. Making the heart bigger, if carried to the extreme, translates as "enlarged heart," which is not so good, leaving increasing the heart rate as the better alternative.

Now if your baseline heart rate is 75 and with effort you raise it to 150, your cardiac output has doubled, which is fine for your purpose. But when by dint of hard work and effective training you get your baseline down to 30, and now with effort you get it up to 150, your output has gone up by a factor of five, which is much better, and so you can do even more, or run even faster, or last even longer.

That's "why" people in great shape have low resting pulses, and world-class athletes like runners get them down to the forties and thirties.


Bill:

I, too, had fun with my Army induction doctors. Or tried to. When the stethoscope was placed on my chest, I held my breath, so he didn't hear anything. Didn't help. The chart entry said "normal breath sounds," and in I went nonetheless.

I ran into some other Army physicians later on who had all kinds of interesting stories to tell, about things like youngsters passing the induction physical with arms withered by polio, and other equally glaring idiocies. How we ever won the war is sometimes hard to understand. Oh yeah, in Vietnam we didn't actually, did we.

And yes, I was an Army Doctor myself for two years, so I can make as many disparaging remarks as I please.
--s/Wofahulicodoc, CAPT MC