Does your "feel good" exercise level need to match MAF180?

by Fred JG
(Yokohama, Japan)

Hi,
I do endurance exercise that includes road bicycle racing, long distance skating and running for pleasure since high school and never really stopped. I did some competition work in skating and cycling which was fun but short due to other commitments.

A few years ago after I already had seen Abraham, I learned a bit about MAF and the usual HR levels.
My training is based on "feel good" which actually means a HR level below the so called MAF180 most of the time.

Due to the fact that I never stopped exercising, my resting HR always has been below 50 and in periods of more frequent training it could jump below 40 and even as low as 30 at times.
My body weight has decreased since age 18 from 74 to 69kg.
Fat reduction estimate is from 13 to 8%.

My "feel good" level is probably burning fat quite well, maybe too much? I eat more than normal recently to compensate losses from longer distance work, as if I am 18 again ;)
Personally I think a 13-14% level of body fat would be better but maybe that requires me to exercise above my comfort zone more?

On the other hand I can handle about 4kg of dehydration now in summer without much issue.
But when I was still 74kg, 4kg weight reduction during one day exercise was quite harsh in my young adult years.

As a reference: I can run now 10km in 49min and HM in 1hr49min a bit below MAF180 level of 125bpm. That is still a bit out of my comfort zone due to some hills as obstacles in my runs close to home.

Garmin connect tells me that my VO2max is between 55 and 57 in the last half year with on average more than 250km per month of running exercise and a few 100km of road cycling exercise.

I think you can use MAF180 as a safe guideline for Aerobic exercise, and depending on the presence of a sport heart the comfort zone exercise HR levels could be lower and still having a reasonable performance level.
I have set my Garmin zones to personal comfort zone taste with zone 3 between 115 and 125.

Nicole's reply:
Hi Fred, thanks for the interesting read. You sound like your years of exercise in your various sports has given you a very good aerobic base.

Whether you exercise at MAF or well below it is all good and the fact that you have no trouble exercising well below your MAF range shows that you have a very good aerobic base. As is the fact that you can race comfortably at MAF and knock out some very good race times. If you feel good in training, are not getting injured and are improving, then you are doing the right thing.

I'm a big believer in enjoying sport so training at a "feel good" level has got to be good. However there are times when our body needs a push and to be tested which is why I also believe in adding in small portions of speedwork from time to time.

Regarding whether you are burning too much fat, I don't know what sort of diet you follow but Phil Maffetone has lots of great nutritional articles on his website which you might find interesting. Here are a couple you might find interesting.
When High Fat Isn't High
Will I burn fewer calories at the MAF heart rate than if I went higher?
Fat Burning Archives
I hope that helps and I hope that you continue to enjoy your running!