The MAF 180 Formula: Determining your MAF HR Subtract your age from 180. Modify this number by choosing one category below that best applies to you:

If you have or are recovering from a major illness (including any operation or hospital stay), are in rehabilitation, have been prescribed any regular medication, or are chronically overtrained, subtract an additional 10.

If you are injured, have regressed or not improved in training (such as poor MAF Tests) or competition, get more than two colds, flu or other infections per year, have seasonal allergies or asthma, are overfat, are acutely overtraining, or if you have been inconsistent, just beginning or returning to exercise, subtract an additional 5.

If you have been training consistently (at least four times weekly) for up to two years without any of the problems mentioned in a) or b), no modification is necessary (use 180 minus age as your MAF HR).

If you have been training for more than two years without any of the problems listed above, have made progress in your MAF Tests, and have improved competitively, add 5.

The resulting HR is the high end of the HR range with the low being 10 beats below. For example, a 40-year old in category b) would have an exercise range of 125-135 bpm. Users can self-select any intensity within this range.

While the 180 Formula is best known for guiding aerobic exercise, initially it was for used for weight- and fat-loss. It soon became popular with athletes in virtually all sports to boost performance (including use with performance horses beginning in the early 1980s), and continues to help virtually all types of people monitor their heart rate. Success is demonstrated by increased fat-burning, improved health, and the ability of athletes to run, bike and otherwise perform at faster paces and increased power at the same MAF HR as determined by the 180 Formula. A primary goal of the 180 Formula is to provide accurate guidance to help people personalize the process of maximizing aerobic function, MAF. For competitive athletes, once a period of exclusive exercise at the MAF HR is completed, with demonstrable improvement in pace or power at the same HR, one can add higher-intensity training if desired. Depending on the individual, the optimal aerobic/anaerobic balance of year-round training may be about 80:20.