Sunday, May 18, 2008

"Low" MAF and MAF.

Ironboom asked: "On Friday you describe two runs: the first run at MAF; and the second run at low MAF. I was under the impression that MAF was a ceiling and not a range. If the latter, how would you go about calculating the range? Would you mind elaborating? Thanks."

First the short answer: MAF is best utilized if you use a ~10 beat HR range.. MAF minus 10 beats is the range. Working within 10 beats (below) is still very effective in building the correct fitness.

Now the long answer: Your aerobic base is your ability (or lack thereof) to burn body fat as a source of fuel during exercise. By working out below maximum aerobic heart rate (or MAF) you will exploit the time that you train more effectively in regards to building your base.

Here is how we figure the number that represents the upper limit of your effort during your base period.

1. Take 180 and subtract your age.
2. Take that number and correct it by the amount next to the statement that best describes your level of fitness:
a. Subtract five beats if you are recovering from a major illness or injury that has kept you from training for six months or more.
b. Leave the number where it is if you have been working out about two to three days per week for at least a year.
c. Add five beats if you have been working out more than three days per week for at least a year.
d. Add 10 beats if you have been working out more than five days per week for at least five years without recurring colds, illnesses, injuries or long periods of burnout.
e. If you are older than 55 years old or younger than 25 years old, add an additional five beats to whatever number you have right now.

The number that I use is 180-36=144... +10 beats because of the number of years I have trained consistently. All of my runs during my base period should be done at a heart rate that is at or below this number. Instead of trying to run exactly at 154 HR which would be impossible- I use a HR range and cap my HR at 154 (note: during my initial "transition" or "adaptation" phase I go easier and use a max HR of 150). The rule of thumb is a 10 beat range so my minimum HR for a run would be 140.. When I say "low MAF " I was running at the low end of the 10 beat range.

MAF- Why this number?
If you go over your maximum aerobic heart rate you switch off your aerobic development (your fat-burning metabolism) and turn on anaerobic metabolism, which uses your stored, and limited supply, of carbohydrates. During base training this is not a good thing to do consistently.

First, once you turn off your fat-burning system it stays shut off for seven to nine hours, even after your heart rate has dropped back down to resting. If you do this consistently you will limit your ability to efficiently burn fat as your primary fuel.

Second, going over your aerobic maximum heart rate causes you to turn on your adrenal system. This is the system that enables people to deal with stress. A little stress is good because it strengthens your entire body and helps your whole system function better. However, if you turn on your adrenal system consistently—which is what happens when you go over your maximum aerobic heart rate—you end up reducing your ability to respond to stress; you build up fat in your cardiovascular system; you reduce the output of DHEA, which is the hormone that enables you to look at life as a good thing; you can become depressed and lose motivation (not a good thing for being consistent with workouts); you can become unable to sleep deeply in the way that is needed to recover your body; and ultimately you will end up not having the reserve necessary when it comes time to race. In other words, you will get burned out and actually lose fitness with regular anaerobic high heart rate training over time. There is a time for the speed work, but the base period is not that time.


Anonymous said...

Thanks so much for taking the time to explain MAF. I'm still a bit new to pure endurance sports (I was a lacrosse player in college) and this is one of the best explanations I've read yet. Simple and concise! Thanks again and love the blog!

Anonymous said...

I have a question. Where does Phil Maffetone get 180 from so you can do the 180-your age. I used this formula during my return to triathlon and seemed to work but then I moved away from it and I overtrained and slowed down .

Ironboom said...

Thanks. That's very well put and very helpful.

Lucho said...

Phil- Maffetone did studies on athletes ranging from elite to recreational and saw the correlation between 180 and Vo2 max. Similar to the Borg scale of RPE which uses a system based on HR's, 180 would be close to an athletes Vo2 max.. with that said.. THIS SYSTEM IS NOT INFALLIBLE. I have always said that the MAF method should be used as a guide and a starting point. Once you have determined more accurate HR zones (like LT and AeT) then you should adjust the training HR's. I think the biggest benefit to the MAF method is that is is conservative and allows for an athlete to train consistently until their muscles and tendons adjust to the pounding.. For me MAF tends to be perfect in relation to my lactate threshold when I'm training for Ironman. As a pure runner I want to train more at my AeT HR which for me is 153-165. ~10-20 beats below LT..

Chuckie V said...

Good stuff Lucho, as always.

Wayne said...

Hi Lucho, I know this posts a little old, yet I've a question related to training within the MAF range and weight loss. You mention that if you train higher than MAF you "turn-off" your fat burning system for a number of hours. On this basis, if someone were to come to you asking for advice on dropping weight where would you predominantly have them training? Thanks.