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Self-Assessment: The MAF Test

A significant benefit of aerobic base building is the ability to run faster at the same effort, that is, at the same heart rate. A heart monitor can help objectively measure these improvements using a test I developed in the mid 1980s called the maximum aerobic function (MAF) test.

Perform the MAF Test on a track, running at the maximum aerobic heart rate. A one- to five-mile test, with each one-mile interval recorded, provides good data. The test should be done following an easy 12-15 minute warm up, and be performed about every month throughout the year. Below is a 5-mile MAF Test of a runner training at a heart rate of 150:

Distance Time (min:sec)
Mile 1 8:21
Mile 2 8:27
Mile 3 8:38
Mile 4 8:44
Mile 5 8:49

During an MAF Test, it is normal for the running times to slow each mile - the first mile should be the fastest and the last the slowest. If this is not the case, it may indicate the lack of an effective warm up. In addition, the test should show faster times as the weeks and months pass. For example, over a four month period, we can see the endurance progress in the same runner from the above MAF Test. Note the aerobic speed improvement between April and July:

  April May June July
Mile 1 8:21 8:11 7:57 7:44
Mile 2 8:27 8:18 8:05 7:52
Mile 3 8:38 8:26 8:10 7:59
Mile 4 8:44 8:33 8:17 8:09
Mile 5 8:49 8:39 8:24 8:15

This improvement is typical during the aerobic base period. Some improve at a faster rate, others slower. Most importantly, if you're not improving within a three- or six-month period, it means something is wrong. It may be a dietary or nutritional factor, excess stress, overtraining (such as too many miles), etc. In some cases, it may be the maximum aerobic heart rate is too high (often from choosing the wrong category in the 180 Formula). Moreover, a reversal of aerobic function, i.e., slowing of aerobic pace during base training, may indicate an impending injury - enough of a reason to perform the MAF Test regularly.

Progress should continue in some form for three to six months or more before aerobic benefits may reach a normal plateau. Adding anaerobic work to the schedule before this plateau may impair (and ultimately even reverse) further aerobic progress.

The greatest benefit of the MAF Test is that it objectively demonstrates aerobic improvement in the form of aerobic speed. These changes also reflect competitive improvement.


A direct relationship exists between the maximum aerobic pace (as measured by the MAF Test) and competition. Essentially, increasing aerobic function improves competition (recall that events lasting more than two minute's duration obtain most energy from the aerobic system).

Data gathered on hundreds of runners I trained over a period of several years showed that the MAF Test was positively correlated with race pace - as the MAF Test improved, so did competition. The chart below, based on actual MAF Tests and 5 kilometer running race times, demonstrates this relationship.

Min/Mile Race Pace Time
10:00 7:30 23:18
9:00 7:00 21:45
8:30 6:45 20:58
8:00 6:30 20:12
7:30 6:00 18:38
7:00 5:30 17:05
6:30 5:15 16:19
6:00 5:00 15:32
5:45 4:45 14:45
5:30 4:30 13:59
5:15 4:20 13:28
5:00 4:15 13:12

The above runners included those who developed an aerobic base, and raced on a flat, certified road course, or track. Most did not perform any anaerobic training, and for most, this was their first competition of the spring or fall racing season. Moreover, 76% of these athletes ran a personal best time for this distance! Similar relationships exist for longer events and for other sports.

The use of a heart rate monitor takes the guess work out of training and can help increase aerobic speed. It can also help prevent injury, ill health and burn more body fat.

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This article was updated by Dr. Philip Maffetone in August 2007

Dr. Philip Maffetone has trained many world class athletes in all sports since 1977. His books include In Fitness and in Health (4th edition, Barmore), Training for Endurance (2nd edition, Barmore), Fix Your Feet (Lyons Press) and many others.