For as long as I can remember, the accepted prescription for developing larger muscles and increased muscular strength was to lift heavy weights. Even standard exercise physiology textbooks say that to activate the type 2-B fast-twitch muscle fibers that are most amenable to gains in muscular size and strength requires you to lift heavy weights. This is based on a physiological principle known as Henneman's size principle. Luckily Henneman attached his name to it before Joe Weider had a chance, or it would have been known as Joe Weider's Muscle Size Principle. In any case, what the principle says is that motor units, which activate muscle fibers, are recruited in order from the smallest motor units to the largest. Since the slow-twitch muscle fibers, also known as "endurance muscle fibers" have the smallest motor units, they are recruited first when you do any weight exercise. But based on incorrect assessments of how muscles react to exercise that was recorded on an electromyograph (EMG) machine, it was long thought that the only way to activate the larger type 2-B muscle fibers was by lifting heavy. Not lifting heavy, according to the EMG, only involved the slow-twitch and the type 2-A fast-twitch muscle fibers. But measuring the extent of activity solely by EMG recordings (the EMG machine works by measuring electrical activity in muscle and can tell you how much of any muscle is involved in the activity) isn't the same as real-world exercise. Despite this, the dogma for years has been that lifting heavy promotes larger and stronger muscles while lifting light to medium weights produces more of a muscle endurance effect since it involves primarily the endurance-oriented slow-twitch muscle fibers.
Bodybuilders took advantage of this information by engaging in periods where they would eat a lot more food, and also emphasize heavy, basic exercises as their training focus. This practice, known as bulking up, was usually done when a contest appearance wasn't imminent. The goal was to acquire as much muscle size as possible prior to starting a precontest diet and training regime that would feature greatly reduced caloric or carbohydrate content in an effort to show as much muscular definition as possible. If things worked well, the bodybuilder would shed any excess body fat that he may have acquired during the bulking phase but retain most of the muscle that he gained. To hedge their bets in this respect, many bodybuilders, especially those interested in turning professional, often resorted to using various anabolic drugs, such as anabolic steroids and growth hormone. In recent years, insulin was added to the anabolic stack since it was thought to be synergistic with steroid and growth hormone. A key concept used during the bulk phase, which often lasted about 6 months or so, was to lift as heavy as possible so as . . .