Muscle growth

Bodybuilders use three main strategies to maximize muscle hypertrophy: 1. Strength training through weights or elastic/hydraulic resistance
2. Specialized nutrition, incorporating extra protein and supplements where necessary
3. Adequate rest, including sleep and recuperation between workouts
Weight training
Weight training causes micro-tears to the muscles being trained; this is generally known as microtrauma. These micro-tears in the muscle contribute to the soreness felt after exercise, called delayed onset muscle soreness (DOMS). It is the repair to these micro-trauma that result in muscle growth. Normally, this soreness becomes most apparent a day or two after a workout. However, as muscles become adapted to the exercises, soreness tends to decrease.
Nutrition
The high levels of muscle growth and repair achieved by bodybuilders require a specialized diet. Generally speaking, bodybuilders require more calories than the average person of the same weight to support the protein and energy requirements needed to support their training and increase muscle mass. A sub-maintenance level of food energy is combined with cardiovascular exercise to lose body fat in preparation for a contest. The ratios of food energy from carbohydrates, proteins, and fats vary depending on the goals of the bodybuilder.
Carbohydrates
Carbohydrates play an important role for bodybuilders. Carbohydrates give the body energy to deal with the rigors of training and recovery. Bodybuilders seek out low-glycemyc polysaccharides and other slowly-digesting carbohydrates, which release energy in a more stable fashion than high-glycemic sugars and starches. This is important as high-glycemic carbohydrates cause a sharp insulin response, which places the body in a state where it is likely to store additional food energy as fat rather than muscle, and which can waste energy that should be directed towards muscle growth. However, bodybuilders frequently do ingest some quickly-digesting sugars (often in form of pure dextrose or maltodextrin) after a workout. This may help to replenish glycogen stores within the muscle, and to stimulate muscle protein synthesis.
Protein
Protein is probably one of the most important parts of the diet for the bodybuilder to consider. Functional proteins such as motor proteins which include myosin, kinesin, and dynein generate the forces exerted by contracting muscles. Current advice says that bodybuilders should consume 25-30% of protein per total calorie intake to further their goal of maintaining and improving their body composition. This is a widely debated topic, with many arguing that 1 gram of protein per pound of body weight is ideal, some suggesting that less is sufficient, while others recommending 1.5, 2, or more. It is believed that protein needs to be consumed frequently throughout the day, especially during/after a workout, and before sleep. There is also some debate concerning the best type of protein to take. Chicken, beef, pork, fish, eggs and dairy foods are high in protein, as are some nuts, seeds, beans and lentils. Casein or whey are often used to supplement the diet with additional protein. Whey protein is the type of protein contained in many popular brands of protein supplements, and is preferred by many bodybuilders because of its high Biological Value (BV) and quick absorption rates. Bodybuilders usually require higher quality protein with a high BV rather than relying on protein such as soy, which is often avoided due to its claimed estrogenic properties. Still, some nutrition experts believe that soy, flax seeds and many other plants that contain the weak estrogen-like compounds or phytoestrogens can be used beneficially as phytoestrogens compete with this hormone for receptor sites in the male body and can block its actions. This can also include some inhibition of pituitary functions while stimulating the P450 system (the system that eliminates chemicals, hormones, drugs and metabolic waste product from the body) in the liver to more actively process and excrete excess estrogen. Cortisol decreases amino acid uptake by muscle, and inhibits protein synthesis.
Meals
Bodybuilders usually split their food intake for the day into 5 to 7 meals of roughly equal nutritional content and attempt to eat at regular intervals (normally between 2 and 3 hours). This method purports to serve 2 purposes: to limit overindulging as well as increasing basal metabolic rate when compared to the traditional 3 meals a day.
Dietary supplements
The important role of nutrition in building muscle and losing fat means bodybuilders may consume a wide variety of dietary supplements. Various products are used in an attempt to augment muscle size, increase the rate of fat loss, improve joint health and prevent potential nutrient deficiencies. Scientific consensus supports the effectiveness of only a small number of commercially available supplements when used by healthy, physically active adults. Creatine is probably the most widely used performance enhancing legal supplement. Creatine works by turning into creatine phosphate, which provides an extra phosphorus molecule in the regeneration of ATP. This will provide the body with more energy that lasts longer during short, intense bits of work like weight training.
Performance enhancing substances
Some bodybuilders use drugs such as anabolic steroids and precursor substances such as prohormones to increase muscle hypertrophy. Most of the substances require medical prescriptions to be accessed legally. Anabolic steroids cause muscle hypertrophy of both types (I and II) of muscle fibers caused likely by an increased synthesis of muscle proteins and are accompanied with undesired side effects including hepatotoxicity, gynecomastia, acne, male pattern baldness and a decline in the body's own testosterone production, which can cause testicular atrophy. Other controlled substances used by competitive bodybuilders include human growth hormone (HGH), which can cause acromegaly. Steroid use is prevalent among professional bodybuilders because such big growth and size is impossible without them.
Rest
Although muscle stimulation occurs in the gym lifting weights, muscle growth occurs afterward during rest. Without adequate rest and sleep, muscles do not have an opportunity to recover and build. About eight hours of sleep a night is desirable for the bodybuilder to be refreshed, although this varies from person to person. Additionally, many athletes find a daytime nap further increases their body's ability to build muscle. Some bodybuilders take several naps per day, during peak anabolic phases.
Overtraining
Overtraining occurs when a bodybuilder has trained to the point where his workload exceeds his recovery capacity. There are many reasons that overtraining occurs, including lack of adequate nutrition, lack of recovery time between workouts, insufficient sleep, and training at a high intensity for too long (a lack of splitting apart workouts). Training at a high intensity too frequently also stimulates the central nervous system (CNS) and can result in a hyper-adrenergic state that interferes with sleep patterns. To avoid overtraining, intense frequent training must be met with at least an equal amount of purposeful recovery. Timely provision of carbohydrates, proteins, and various micronutrients such as vitamins, minerals, phytochemicals, even nutritional supplements are acutely critical.
It has been argued that overtraining can be beneficial. One article published by Muscle & Fitness magazine stated that you can "Overtrain for Big Gains". It suggested at if one is planning a restful holiday and they do not wish to inhibit their bodybuilding lifestyle too much, they should overtrain before taking the holiday, so the body can rest easily and recuperate and grow. Overtraining can be used advantageously, as when a bodybuilder is purposely overtrained for a brief period of time to super compensate during a regeneration phase. These are known as "shock micro-cycles" and were a key training technique used by Soviet athletes. However, the vast majority of overtraining that occurs in average bodybuilders is generally unplanned and completely unnecessary.
Non muscle-developing methods
Some bodybuilders, particularly at professional level, use substances such as site enhancement oil to mimic the appearance of muscle where it may otherwise be disproportionate or lagging. Surgical methods are also often employed to remove steroid-related gynecomastia in male bodybuilders, and breast implants in female bodybuilders who wish to retain a feminine physique, which can be compromised in terms of breast reduction by intense weight training.