The Aerobic Fallacy

Aerobics trains the body to become very efficient at using fat and storing fat because the predominant fuel source in aerobic exercise is fat. Did you ever hear of the “fat burning zone?” Throw it out the window. It is quite possibly one of the most misleading pieces of fitness information ever! If your car is more efficient at using fuel, is it going to use more or less of it? The correct answer is less of it, which is great for your wallet but not your body if we’re talking about efficiency of fat use for exercise. We want the hummer engine, the big gas-guzzler, the most fuel inefficient car we can find to burn body fat.

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To equate this to exercise, we want high intensity exercise with rest interspersed. We want a very large oxygen deficit. In a study by Tremblay and colleagues, it was demonstrated that high intensity exercise, specifically intermittent, supra-maximal exercise, is the most optimal for fat loss. There were two groups—the long, slow distance aerobic endurance group (LSD) that was on their program for 20 weeks and the high intensity interval training (HIIT) group that was on a program for 15 weeks. The amount of energy utilized (calories) by the LSD group was DOUBLE that of the HIIT group. However, six skin fold measurements demonstrated greater loss in the HIIT group than the LSD group. When this was expressed on a per energy basis, the HIIT group’s reduction in skin folds was nine times greater than the LSD group. That is what you call more bang for your buck (Willey 2007).

The HIIT group created large post-exercise oxygen consumptions (EPOC), which can take up to 48 hours for your body to fully recover from. This is where fat loss occurs, not during the hours spent on the treadmill. In another published study by R. Bahr and performed at the Department of Physiology at the National Institute of Occupational Health in Oslo, Norway, it was demonstrated that low intensity (defined as 65 percent of maximum heart rate for less than one hour) led to a total EPOC of only five calories. On the other hand, intensive exercise where the heart rate was above 85 percent of the maximum, led to EPOC values of up to 180 calories (Staley 2005).

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If the body is more efficient at burning and storing fat, this will also equate to a lowered metabolism, which, again, is not a good thing. We are looking for exercise that takes the body hours to recover from (large EPOC). You will not even be aware of this recovery, but if you were put in a lab, oxygen debt would still be elevated for a few hours to 48 hours! Did you ever notice that even after running a few miles, you could hold a conversation during it or immediately following it? The human body recovers very quickly from aerobic exercise. This is not optimal for fat loss.

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In a different capacity, aerobic athletes, most notably marathon runners, are the most injured group of athletes in the world. Every time the foot strikes the ground, 3–5 times the body weight is applied in force up through the skeletal system. Ouch! The stress hormone cortisol is also produced in very large amounts when the body is constantly performing aerobics. Despite what you see on those silly commercials, cortisol is essential to the human body. However, high amounts will cause the accumulation of body fat, most visibly around the mid-section. High cortisol will also negatively impact your adrenal glands over time. Distance runners who train upward of 100 miles per week do not expend more than 800–1300 “extra” calories each day above their normal energy requirements (McArdle 2001). Does that sound like it was worth their time investment?

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