Arnold frequently supersetted biceps and triceps movements—or, in other words, performed exercises back to back—to bring an enormous amount of blood into his arms. Blood carries oxygen and nutrients critical for growth, but these supersets also enabled Arnold to achieve his ultimate training goal: a killer pump. Supersetting a smaller muscle group like arms is easier than a larger one like legs, though Arnold often did that pre-contest as well.
The general strategy adopted by most present-day competitive bodybuilders is to make muscle gains for most of the year (known as the "off-season") and, approximately 12–14 weeks from competition, lose a maximum of body fat (referred to as "cutting") while preserving as much muscular mass as possible. The bulking phase entails remaining in a net positive energy balance (calorie surplus). The amount of a surplus in which a person remains is based on the person's goals, as a bigger surplus and longer bulking phase will create more fat tissue. The surplus of calories relative to one's energy balance will ensure that muscles remain in a state of anabolism.

Usually, people associate the word diet with days of starvation and pain. However, that is not the correct definition of a diet. The word diet refers to the food choices that we make on a daily basis. Even if you don’t think you that you are on a diet, guess what?! You already are following a diet. Whether you eat candy all day every day or oatmeal, that is your diet.
In the fourth and final week of the program, you’ll train four days in a four-way split that hits each bodypart just once (except for calves and abs, which are each trained twice). Four-day splits are common among experienced lifters because they involve training fewer bodyparts (typically 2–3) per workout, which gives each muscle group ample attention and allows you to train with higher volume. As you’ll see, chest and triceps are paired up, as are back with biceps and quads with hamstrings, each a very common pairing among novice and advanced bodybuilders. Shoulders are trained more or less on their own, and you’ll alternate hitting calves and abs—which respond well to being trained multiple times per week—every other workout. No new exercises are introduced in Week 4 so that you can focus on intensity in your workouts instead of learning new movements.
It's never too late to start. In one study of elderly men and women (mean age 87) who lifted weights three times per week for 10 weeks, strength increased a whopping 113%! The improvement in strength enabled the elderly participants to also walk faster (12% faster than before the study), climb 28% more stairs, and it even caused the muscles in their thighs to increase by more than 2.5%.
Carbohydrates play an important role for bodybuilders. They give the body energy to deal with the rigors of training and recovery. Carbohydrates also promote secretion of insulin, a hormone enabling cells to get the glucose they need. Insulin also carries amino acids into cells and promotes protein synthesis.[26] Insulin has steroid-like effects in terms of muscle gains.[27] It is impossible to promote protein synthesis without the existence of insulin, which means that without ingesting carbohydrates or protein—which also induces the release of insulin—it is impossible to add muscle mass.[28] Bodybuilders seek out low-glycemic 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. However, bodybuilders frequently do ingest some quickly digesting sugars (often in form of pure dextrose or maltodextrin) just before, during, and/or just after a workout. This may help to replenish glycogen stored within the muscle, and to stimulate muscle protein synthesis.[29]