Dr. Philip Maffetone is a bit of a household name amongst runners. He believes that doing the least harm to one’s body by monitoring effort via heart rate leads to improved athletic performances. The method is simple: determine the heart rate at which one’s body most efficiently burns fat, and then train at or below that threshold (the aerobic zone). Whenever an individual trains in the zone above the fat-burning threshold (the anaerobic zone), he or she is more likely to become injured, over-trained, or burned out on running. From a biochemical standpoint, training in the aerobic zone will cause the body to burn fat for fuel, not carbohydrates. When training in the anaerobic zone, the body requires more carbohydrates, and thus leads to sugar cravings. Maffetone asserts that burning fat is better for the body than burning carbs, because quick carbohydrates, like sugar, raise the body’s insulin levels and decrease one’s ability to metabolize fat. Therefore, quick carbohydrates are deemed “bad” foods if following this training regimen.
To begin heart rate training, all that is necessary is a heart rate monitor and to know one’s maximum aerobic heart rate. The calculation for maximum aerobic heart rate is simple:
1. Subtract your age from 180
2. If you are recovering from a major illness, subtract an additional 10
3. If you are injured/out of shape, have allergies, asthma, or easily become ill, subtract an additional 5
4. If you have been training consistently for more than 2 years, and have improved without injury, add 5
Therefore, for a healthy 40 year old, maximum aerobic heart rate is 140.
The major performance benefit of training in the aerobic zone is that aerobic capacity will improve, which is especially important for athletes whose competitions last more than 60 minutes. Additionally, for the casual athlete, the heart rate method helps the body more efficiently burn fat, which leads to weight loss. By avoiding training the anaerobic system, one can theoretically avoid weakening the aerobic system. A stronger aerobic system can help reduce fatigue, inflammation, injuries, overtraining, and hormonal imbalances.
There are many common criticisms to heart rate training. First and foremost is that the “180 rule” for determining maximum aerobic heart rate is not one-size-fits-all. Although there are slight adjustments available to account for various medical histories, these adjustments are vague blanket-statements. A number of factors affect maximum aerobic heart rate, and include, but are not limited to: race, sex, occupation (i.e. physical vs. sedentary job), training history, weight, history of heart disease, and metabolism. To truly determine one’s fat-burning zone requires a stress test to be performed in a sports performance lab, which can be both costly and difficult to find. A second criticism is the equipment involved. A reliable heart rate monitor can cost upwards of $100, but still suffer from malfunctions. Common reasons to receive a “no reading” message on a monitor include extreme heat or extreme cold. Finally, a third common complaint of heart rate runners is that, in order to maintain an effort in the aerobic zone, running pace may be much slower than which is comfortable. If living in an area that is particularly hilly or humid, running may have to be replaced with walking, because both of these geographic issues can cause large increases in heart rate. One benefit of heart rate training is that progress can be monitored over time by tracking effort at faster paces; however, some people become discouraged because, even at peak fitness, heart rate can be influenced by factors such as caffeine, stress, dehydration, and lack of sleep.