Definition: "An ergogenic aid is any substance or phenomenon that enhances performance "

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Trained body burns more fat with gentle endurance exercise

Whether and how much endurance training bodybuilders should do is a subject that athletes and trainers will never agree on. Irritating? Well, we're only too happy to fan the flames, so we dug up an article from fifteen years ago which suggests that endurance training can help keep fat reserves under control even when athletes don't exert themselves too much.

Nothing burns kilojoules like endurance sports. An hour and a half of running will burn off more energy than any circuit training we know of. But the big disadvantage of endurance training is that daily training sessions of 1 to 3 hours break down muscle tissue. For endurance athletes this is not a problem, but for bodybuilders this is not the case. That's why the coaches of strength athletes who want to boost their fat burning usually advise interval training.

In 1994 Texan sports scientists published an article in the American Journal of Physiology. The article reports the results of a trial they did with 5 trained endurance athletes and 5 subjects who did no exercise. All were healthy men, average age 30. The athletes had been training between 1 and 3 hours daily for 3 to 8 years.

The researchers got the test subjects to walk gently on a treadmill for 4 hours and measured how much fat they burned as a result. Although both groups had the same amount of exertion, the endurance athletes burned more fat. The white bars represent the athletes, the black bars the non-athletes.

Trained body burns more fat with gentle endurance exercise

As a result of training the athletes' muscle cells had apparently learned to burn more fatty acids and save more glycogen. But the extra fatty acids that were burned did not come from the fat layers, the researchers discovered when they measured the concentration of free fatty acids in the subjects' blood. The athletes' blood had lower amounts, shown by the curve with the white circles.

Trained body burns more fat with gentle endurance exercise

Endurance athletes burn more fat during low-intensity activities, but the fat comes from the muscles. Ergo: endurance sports are not good for bodybuilders. At least, that's what you'd think.

Maybe. Then again, maybe not. "Endurance exercise training has been shown to increase the lipolytic response to catecholamines in adipocytes isolated from abdominal adipose tissue", the researchers write. "Our results support the idea that adipose tissue sensitivity to beta-adrenergic stimulation in vivo was enhanced in the trained subjects. In the present study, lipolytic rates, expressed per kilogram body weight, during exercise were similar in both trained and untrained subjects despite presumably lower circulating catecholamines in the trained group."

Endurance sports make your fat cells more sensitive to pep-hormones like adrenalin and noradrenalin. These are released by strength training, and in even higher quantities through interval or circuit training. Perhaps it's worthwhile after all for strength athletes to do a little bit of endurance training?

Am J Physiol. 1994 Dec; 267(6 Pt 1):E934-40.