Build the Aerobic System

Improve your fat-burning “engine.”

Our aerobic muscles burn fat for energy, improve circulation and immunity, support the joints and bones, and provide motion all day long without fatigue.


The Aerobic System

The aerobic human body is associated with improved health, longevity, recovery and endurance. When not well developed, poor aerobic function leads to a serious deficiency.

Aerobic deficiency is common in those who exercise too hard, those who are overstressed, and in people who are inactive. This occurs with poor fat burning and reduced muscle support and function. Some common signs and symptoms:

  • Chronic fatigue.
  • Frequent injury.
  • Hormone imbalance.
  • Increased body fat.
  • Chronic inflammation.
  • Poor endurance.

Building maximum aerobic function — also known as MAF — occurs through relatively easy exercise at a heart rate (HR) specific for your needs. The best aerobic training feels easy and relaxing.

Aerobic deficiency is one of the main risk factors for overtraining. Because of this, the following survey — which helps ascertain your risk for overtraining — is also illustrative of the state of the aerobic system even for individuals who do little to no athletic training.

The 180-Formula

Find Your Maximum Aerobic Function Heart Rate, or “MAF HR”

The 180-Formula, an alternative to a one-on-one clinical evaluation, provides you with an accurate exercise HR that helps guide optimal aerobic development.

 Find your MAF HR in 2 steps.

  1. Subtract your age from 180 (180age).
  2. Modify this number by selecting one of the following categories that best matches your fitness and health profile:

a) If you have or are recovering from a major illness (heart disease, diabetes, hypertension) any recent surgery or hospitalization, or take any regular medication, subtract an additional 10.

b) If you are frequently injured, get more than two colds or flu per year, have allergies or asthma, are inconsistent with exercise, or your athletic performance has plateaued, subtract an additional 5.

c) If you have been exercising at least 3-4 times a week for at least a year without any of the problems in (a) or (b), keep the number (180–age) the same. 

d) If you are a competitive athlete training for more than a year without any of the problems in (a) and (b), and have made progress in competition without injury, add 5.

There’s more to understanding the 180-Formula. Read the in-depth article.

Next step: Take the survey below.

Take the survey

Take the following survey to determine whether you are at risk for overtraining. This survey will provide you with a personalized risk level (low, moderate, or high) that you can use to improve your health.


A high level of risk doesn’t mean that you have a serious health condition. It means that due to your present situation (lifestyle, health and habits), you have a higher risk for this condition.


The best aerobic training feels easy and relaxing.

The MAF Test

Applies to:

High Risk
Moderate Risk
Low Risk

The MAF Test is a simple aerobic evaluation that allows you to track your progress. It can be performed while running, walking, cycling or during other workouts. A runner, for example, warms up very slow for 15 minutes (walking or jogging) and then runs at the MAF HR, recording each mile or km.

The MAF Test is typically performed on a flat oval track of a known size (such as 400m), but it can also be performed on a relatively flat stretch of road, using a GPS device to keep track of distance (MAF-GPS test).

Monthly tests should demonstrate faster paces, or more power, at the same MAF HR, otherwise, aerobic development is not occurring. If your speed plateaus (stops increasing) for two or three tests, or decreases, this is a warning that aerobic function may be compromised or diminishing.

For those without good aerobic function, it often takes three to six months of strict aerobic exercise to build the aerobic system. During this time it is important to avoid exercise above the MAF HR.

Aerobic Training Guidelines

Applies to:

High Risk
Moderate Risk
Low Risk

Individual exercise needs vary considerably, but don’t think more is better. Start with your normal time, not distance. Increase no more than 10 percent every two weeks.

If you are new or haven’t exercised consistently for more than about three months:

  • Start with only 30 minutes of aerobic exercise three times per week. Since our recommendation is that the warm-up and cool-down last 15 minutes each, you’ll only be warming up and cooling down at first.
  • As the weeks progress, gradually increase the time spent at your MAF HR, but never exceed it.

Strength Training

Applies to:

Low Risk

Knowing when and how to reincorporate strength and power training into an exercise routine is very important. While this training has many health and fitness benefits, doing too much (or incorporating it too soon after starting a new exercise regimen) can impair the aerobic system.

Training for added strength and power, including speed, comes in many forms such as:

  • Weight/strength training. (See an exception: Slow Weights LINK)
  • High intensity interval training (HIT).
  • Fartlek.

Strength and power training can be included in your routine when MAF Tests have consistently improved, indicating that the aerobic system can tolerate high intensity training without impairing health.

Continue performing the MAF Test monthly to make sure aerobic function does not diminish. If it does, temporarily eliminate strength and power training until aerobic function is restored.

For most individuals with healthy aerobic systems, a yearly ratio of aerobic to strength training is about 80 percent aerobic and 20 percent anaerobic (strength and power).