Originally Posted by
drewguy
I'm not trying to use HR max as some measure of fitness. I know it's genetic. And in terms of fitness I'm cycling more than I did last year. The question I had is figuring out why when I was at maximum exertion last year, I'd hit peak HR that's about 10-15 higher than when I hit maximum exertion now. And I could ask the same question regardless of whether that peak HR was truly my max, although based on lengthy observation plus seeing it at what I consider my max HR for both running and cycling, I consider it to be pretty good number.
It's a terminology thing. When you say maxHR, it seems you don't really mean that, you seem to mean the highest HR you might see on a regular basis, not the one when you see Moses just before everything almost goes black.
HR is much more difficult to use than power as a cycling metric. Not that it's a bad thing, but it's more complicated in that it contains a lot more information than does power. It can vary at the same power by quite a bit, from hour to hour, day to day, month to month, and year to year. One way to get a handle on this is to go by breathing, watching what your HR is doing at various breathing levels, and getting information from that.
OK, so why does HR vary, which might be the subject of your post? HR drops as blood volume increases and vice versa. Blood volume rises with training, and fairly quickly, in weeks (I think). Ventricle wall thickness increases with training, which increases stroke volume, which decreases HR
at the same effort. The athlete also usually notices this in a decrease in morning resting HR. This happens over a period of years. During a ride, HR will vary with hydration and blood sugar. Dehydration increases it, low blood sugar drops it.
A good way to understand HR variation at the same effort is to track oxygen consumption, which does not vary to the same extent with effort (power). One tracks oxygen use by monitoring breathing rate and depth. Look up VT1 and VT2 - I don't want to do all that typing. IOW notice HR, but go more by breathing to estimate current output.
So you can't use HR as a measure of fitness. Use VAM for that, or sustainable speed in still air. HR doesn't contain that information. You can always take the shortcut and buy a PM. One thing which riders new to training notice right off is how high their HR gets the first season and how quickly it comes up. If they keep training that changes fairly drastically. When I start a run, it takes over a mile before my HR comes up to cruising level. Before that, I go by breathing, and after that it's useful to note variations on climbs and descents, not as absolute numbers, but compared to my cruising HR at my desired breathing rate. Cycling is similar, except that I takes me more like an hour to really warm up.