I am 47 and have been doing some form of aerobic exercise (running, and now cycling) for 25 years. Today, I thought I would see how high I could get my heart rate while riding a spinning bike at the gym. I warmed up, cranked the tension down pretty good, and then during one very intense effort saw my heart rate rise to 166 bpm. I could hold this level of effort only for a short time (< 30 seconds). I suppose I could have probably pushed myself a little more to the point where I was puking, but I could never hold that for more that 5 or 10 seconds.

Anyway, a max heart rate of 170'ish sounds a little low. Even the standard formula puts my max at 175. I suppose if someone stuck a cattle prod to my behind when I was at 166 bpm, I could prossibly hit 175, but I can't imagine the pain that would be involved.

Do you think it would be accurate, based on this, to estmate my max as 170-175, or could it even be higher depending on motivation, rest, energy level, time of day etc? Can I increase my max if I train in a specific way? Or is your max what genetics tells you it is at the moment?

It is what it is. Bigger/faster is not better training. your Max heart rate could be 10 or 15 BPM more or less than another 47 year old with the same exercise lifestype history.

Read this:

https://www.bikeforums.net/training-nutrition/43102-2x20-anaerobic-threshold-test.html

and this:

https://www.amazon.com/Heart-Zones-Cy...7066580&sr=8-1

Bottom line, lactate threshold is more meaningful that max, and testing for it is far easier. BTW, forget age formulas for max, they are meaningless.

Well, it takes me a gradual increase of effort over time to get up near my maximum heart rate. For me, the heart rate sort of lags the effort a bit.

Now it also seems to me that maximum heart rate is exercise specific. In other words, the same person will get different maximum heart rates doing different aerobic activities like running, cycling, rowing etc. Finally, I do not think that maximum heart rate is an indicator of fitness. I did not fool with this when I was out of shape. But my maximum heart rate does not seem to change with fitness level. (I have not done a study on this though). I believe that one's resting heart rate does reflect aerobic fitness though.

The body has a maximum HR that will decrease with age, is completely genetic, and does not increase with fitness. However, the maximum HR you will achieve will differ depending on activity, and may increase with fitness. Minimum HR is largely genetic and not really related to fitness. Seems to be related more to the amount of muscle the heart has to feed with blood. I have a much higher resting HR (high 30/low 40) than my lowest (32). I am far more fit now, and I weight about 20 lbs. more than I did then, mostly muscle...

Maximum heart rate is largely a useless measure, and the standard formulas are also mostly useless.

What is more interesting is the heart rate that you can maintain for a given period of time. If you look at the field test thread and give that a try, that's a good way to judge your aerobic fitness over time, and you may be able to get up to your maximum in such an effort (that's where I hit my max).

Hitting max in a field test is very different than a short hard effort. You will be close to your max, hit a small roller, try to ride faster, and be unable to do it.

I will mention that field tests, if you do them right, provide more pain than anything else I've done in cycling.