How to build muscle mass? The question of the development of muscle mass (muscle hypertrophy) is of particular importance for all athletes for athletic or cosmetic purposes easier to train with weight lifting. The main objective for all the athletes’ strength and power sports such as football, rugby, power lifting, is to provide the right ratio between the width of the cross-sectional area and muscle strength. Muscle mass is also very important for bodybuilding athletes where during competition is assessed both the quantity and quality of the muscles. The development of hypertrophied muscle mass is not a practice exclusively for competitive athletes in recent years many people have approached the world of gyms, and among these the majority is dedicated to weight training with the aim to improve their physical appearance. The attention towards the development of muscle mass is therefore a widespread phenomenon by a large and diverse population to muscle hypertrophy both for sports purposes, both for aesthetic purposes. In untrained subjects the development of muscle mass is virtually nonexistent in the early stages of training, the results arising from the early stages of training resulting from a neuromuscular adaptation. After a couple of months of training hypertrophy begins to rule, and gradually becomes the primary factor responsible for the increase in performance in terms of strength and endurance, with the upper portion of the body that has a faster response than the muscle groups leg. A very important aspect to keep in mind is the genetic predisposition, we are all born with a muscular development more or less marked in relation to the indications of our DNA, while each of us possesses a capacity for adaptation to stress and therefore a potential development muscle mass is also closely related to genes. This is to clarify that not everyone can become giants like Arnold Schwarzenegger because they do not all have her own genetic heritage that gives itself a great starting point and an equally great capacity for muscle development in response to the training stimulus. Everyone should be able to understand and accept their limits of development connected without fail with their genetic heritage. It is no coincidence that the doping bodybuilding excellence is represented by steroid hormones, ie those molecules that interfere with the instructions of the genetic and cellular stimulate protein synthesis. A fundamental principle guiding the planning of targeted training plans for the development of muscle is represented by what is defined as the overload principle because after the first adaptations is important to continue to provide increasing stimulus intensity to maintain active response systems muscle adaptations in relation to the theory of overcompensation. Currently the scientific literature does not define a unique training method for the development of muscle mass, on other hand, bodybuilders train with loads to moderate intensity and short recovery time between sets, a method that induces a significant metabolic stress, on the other side of power lifters train with high loads and long recovery time between sets. Although both training systems prove to be equally effective in hypertrophic development when there is no scientifically proven method that is capable of maximizing muscle growth.