Number crunching - exercise heart rates

While I was walking my 2 miles on the treadmill on Wednesday evening, I was thinking about what my "target heart rate" should be if I want to achieve full aerobic benefits. There are a couple of popular formulae available on the Internet, a newer one (Karvonen) which takes your resting heart rate into account (as well as your age). The older formula simply uses your age. You calculate your maximum heart rate, then (depending on your objective) you use a percentage of that to calculate your target heart rate.

For me, being almost (be not quite) 50, the numbers work out as follows:

Old formula

Start off with 220. Deduct my age (so, 220-50=170). That's my maximum heart rate.

Multiple by the desired training intensity which, for me, is 70% (so, 170 x .70 = 119)

New formula

Start off with 220. Deduct my age (so, 220-50=170). That's my maximum heart rate.

Now, deduct my resting heart rate (so 170 - 80 = 90). That's my heart rate reserve. 

Next, multiply my heart rate reserve by the desired training intensity (so, 90 x .70 = 63)

Then, add back in the resting heart rate (so, 63 + 80 = 143)

For a moderate workout, where your breathing quickens but you are not out of breath (you can still easily carry on a conversation), and you get a light sweat after ten minutes, you should aim for a training intensity of between 60% to 70%. For a more vigorous workout, where you are taking deep and rapid breaths (you can't speak very much) and you are sweating after just a few minutes, you should aim for a training intensity of between 70% to 80%. Athletes in good condition can aim to reach 85% of their maximum heart rate. 

More to follow ...