Column by John Parrillo from Parrillo Performance.
Definitely. And the reason has to do with the muscle fibers, the basic element of the muscle. Muscle fibers are divided into three types: slow-twitch (also called slow-oxidative (SO) or Type I), fast-twitch oxidative-glycolytic (FOG or Type IIa) and pure fast-twitch (FT or Type IIb). The slow-twitch fibers contract slowly. But they can Natural Bodybuildingsustain their contractions for long periods without fatiguing. These fibers are used more in endurance activities such as long-distance running or swimming.
Genetically, athletes with a predominance of slow-twitch fibers perform well in endurance competition. Slow-twitch fibers get most of their energy from burning fat, a process that requires oxygen. This is further kindled by the fibers’ ample supply of blood vessels, mitochondria (cellular furnaces where fat and other nutrients are burned) and glycogen and blood fats inside their cells. The pure fast-twitch fibers are different. They contract rapidly but fatigue more easily. Their energy comes from burning glycogen. There are fewer mitochondria in the cellular make-up of fast-twitch fibers. Athletes who excel in speed or power events such as sprinting or weight lifting appear to have a higher percentage of fast-twitch fibers. Fast-twitch oxidative-glycolytic fibers contract quickly too, but they do not fatigue as fast. This may be because they have more mitochondria than the pure fast-twitch type but less than the slow-twitch fibers. But like the slow-twitch variety, fat can be burned by the fast-twitch oxidative-glycolytic variety for energy. Interestingly, you can change pure fast-twitch fibers into fast-twitch oxidative fibers by high-volume training such as long duration aerobics or intense high-intensity training.
Furthermore, this type of training actually increases the number of mitochondria in fast-twitch fibers to levels higher than those found in slow-twitch fibers. With more mitochondria in muscle cells, the fast-twitch muscle fibers burn more fat. Through high-volume training your body literally becomes as fat-burning machine. If you want to burn more body fat, I suggest that you do high-rep work using heavy poundages. Work out intensely – so that you are breathing hard each time you finish a set. Increase the frequency and duration of your aerobics too. This regimen is precisely how competitive bodybuilders train to lose fat before a contest. It’s an all-out approach that verges on over-training. But that’s what you have to do to change the fat-burning capacity of your muscle fibers. Remember too that you must follow a high-calorie, nutrient-dense nutrition program (food and supplements) as outlined in the Parrillo Performance Nutrition Program to fuel this level of intensity.