I’m sure someone can give a good explanation as far as true max heart rate as it relates to someone being hooked up to all the fancy lab equipment but as far as your textbook goes it talks about maximum heart rate in the number of beats per minute that you shouldn’t really go over when training for safety reasons (in the general population…I suspect athletes can and do go over in certain training sessions)
So since you know the formula….220-age…we’ll take a 50 year old man (or woman, no need to discriminate) and you get 170 MAX heart rate. Ok, so now what? Well, we have to apply that info. In the cardio section of the book it talks about different training zones…you know, phase 1, 2 and 3. Phase one has a client work out to around 65-75% capacity. Ok great! but 65% of what?…oh ya, 65% of the Max heart rate you calculated earlier. If you want your client to train at 65% intensity then take 65% of 170…that’s 110 beats per minute. So if your client rides the bike and maintains a heart rate of 110 BPM, they would be working out at 65% intensity…or 65% of their max.
Imagine you own a hotel with 100 rooms (Your max capacity) and one weekend you want a fairly moderate weekend. You don’t want to be too busy but you don’t want to slack off either so you decide to book a 65% capacity. 65% capacity (intensity) of your total capacity of 100 rooms is 65! If you book 65 rooms you will be working at 65% capacity that weekend.
Remember though, the formula is a general guide and your textbook even says that the creator of the formula never meant it to be an absolute guide to training intensities. I often use the talk test or RPE method when working with people…and even when I’m just training myself. I find the RPE is pretty good. I generally know when I’m slacking and when I’m going to pass out.
Oh, almost forgot…you probably read in that same chapter about another formula, the Karvonen method, that takes into account the resting heart rate when figuring out the Max HR….same deal though…once you know the Max HR you can just multiply it by the intensity you want your client to work out in.