Lunchtime Run Thoughts.

People regularly ask me what I think about when I'm running. The answer truly is "anything." The other day, however, it was more specific to running:

There used to be a theory that a person only had a finite number of heartbeats available to them during their lifetime. There was no scientific basis for this, but many people took it as fact in any case. This “fact” was then used to justify why a person should not exercise: it used up extra heartbeats by increasing heart rate.

However, we also know that resting heart rate decreases with increasing fitness. . My question is this: even supposing that the finite heartbeat theory were true (it’s not, of course, at least not in any time frame that will limit our lifespan) would the decrease in resting heart rate be enough to compensate for the increase in heart rate while exercising?

I think I should try a few calculations.

So, average resting heart rate according to Mayo is between 60 and 100 bpm. I will assume 75 or so as an average. Currently, my resting heart rate is about 45.

My maximum heart rate, estimated based on age, varies between 179 and 195, depending on who you ask. That sounds low to me, but I’ll go with it and say 185. Seemed to be the consensus.

So, let’s say I train at 85% of my max heart rate for about an hour a day. That’s a high estimate, as 85% of your max heart rate is about your lactate threshold. I don’t train anywhere near that level most of the time.

Beats per week = (60 min/hr x 23 hrs/day x  7 days/week x  45 resting heart rate ) + (60 min/ hr x 1 hr/day x 7 days/week x 185 x 85%)  = roughly 500745 beats per week.

I realize this is an estimate, and probably not accurate. But, let’s compare that to somebody sedentary, with a 75 bpm resting heart rate:

Beats per week = (60 min/hr x 24 hrs/day x 7 days/week) = 756000 beats per week.

Even if I adjust my heart rate up to 50 or 60 bpm I end up ahead by 100000 beats per week.

So, though that was already disproven, had the doubters done a little math, they should have encouraged exercise, if only for the benefits of a lower resting heart rate.