Does Aerobic Exercise Cause Muscle Wasting?
This is a claim you hear often, especially among bodybuilders, but also among some personal trainers. The most extreme version is aerobics makes you fat, the reasoning being that it leads to loss of muscle, which lowers your metabolism, causing you to gain fat because you’re now eating too much for your slow metabolism. These types of claims are based on some truth, as we’ll see, but are highly exaggerated. Your muscles are not going to waste away to nothing because you run half an hour per day. There are some mechanisms by which aerobic exercise can interfere with muscle growth or cause actual muscle loss. The first is that concurrent aerobic exercise and strength training lead to competing adaptations in muscles. For example, steady state aerobics leads to endurance adaptations such as increased mitochondria (aerobic energy factories) and aerobic enzymes in the muscle cells, while strength training can lead to hypertrophy, or growth in muscle fibers. The bottom line is that doing bot
