Weightlifting is the most direct way to add muscle mass and strength to your body. However, there is an unbelievable amount of science and complexity behind this seemingly simple practice. Muscles are intricate devises, and there are many cool ways to trick them into growing bigger and more powerful. This form of exercise allows you to target specific muscle groups and work them to exhaustion. Your body, in an effort to adapt, builds stronger and larger muscles in response to this activity.
When you lift weights, your body quickly uses up all of the oxygen present within the muscle cell. A bi-product of the intracellular activity following the depletion of oxygen is lactic acid. Lactic acid is what makes your muscles burn while you lift. When your muscles have too much lactic acid floating around within them, they cease to function, but it is at this point that they receive the greatest impulse to grow. Lifting weights causes a tremendous amount of strain on muscle fibers. This strain creates some damage to the muscle, and depletes its energy stores. Your body must now repair this tissue, and refill the stored sources of fuel. Your muscles become sensitive to the body’s anabolic hormones such as insulin and testosterone. They become desperate to absorb proteins to rebuild damaged tissue and both fat and carbohydrates to fuel their function/regrowth. In other words, when muscle cells burn up all of their stored energy, they become more receptive to hormones that help to stuff nutrients into them, creating growth. Your muscles work hard, and then they need to be fed. If proper nutrition exists in conjuction with resistance/weight training, your muscles grow rapidly. One of the main differences between weightlifting and other forms of exercise is that weightlifting allows you to isolate a specific muscle group, and create a massive demand for growth in that section of the body alone. When only exercising one muscle group at a time, that particular muscle fails before the heart becomes exhausted. This allows for site specific growth, and that can be pretty handy for correcting muscle imbalances, creating physical symmetry, or developing power.