Posted by: Paul
The question of exactly what makes muscles grow bigger is constantly being studied by the sports science fraternity. New discoveries seem to add to the rather complex procedure on exactly how a muscle gets bigger. But before we examine any new discoveries lets first examine what we do know about muscle growth.
If you are a bodybuilder or someone who trains with weights then you will know that muscles do not grow when you train, they grow after you have trained as they try to repair the damage you have done in the gym. This process of repair tells us that it happens at a cellular level.
The damaged muscle fibers are fused together during this important time of muscle repair fusing the muscle fibers tightly together to form new myofibrils or muscle protein strands. In an attempt to prevent any farther muscle damage your muscles create these new myofibrils thicker and stronger than they were previously to prevent farther damage.
The bottom line is that your muscle growth will only occur when the rate of any muscle protein synthesis happening is greater than the muscle protein breakdown happening. This only happens when resting if your depleted nutrient requirements are met to enable protein synthesis.
In the last 30 year's sports science has discovered that your muscle cells actually do more than that as they are able to add more muscle cells to your existing muscle structure. These muscle satellite cells or muscle stem cells are actually able to increase the nuclie to existing muscle cells increasing the myofibrils growth.
It is only recently that sports science has discovered the difference between these satellite cell activation principals showing us why some "genetically gifted" bodybuilders (called extreme responders) are able to activate more satellite cells from training than normal people.
Sports science tells us that muscle grows in three ways. Progressive resistance disrupts homeostasis of your muscle cells and this in turn spurs the strengthening or growth of a muscle in three ways.
#1: Muscle Tension
Muscle growth is only achieved when a load is lifted which is greater than a load previously lifted. It is this additional tension required to lift a weight that causes changes to the actual muscle chemistry. This releases specific growth factors like satellite cell activation and the release of mTOR.
It is important to note here that muscle tension, lifting a heavier weight than you lifted the last time you trained that body-part, directly affects the connection of the motor units connecting to muscle cells. This explains why some people might be stronger but not have as much muscle as other people.
#2: Muscle Damage
When you feel sore after training (DOMS) you will be feeling your satellite cells activation as they release inflammatory molecules and some immune system cells to speed up repair. Please note that this does NOT mean you have to get sore the day after training to ensure muscle growth.
#3: Metabolic Stress
Metabolic stress is when you get a "pump" or you feel the "burn" when training. This "pump" feeling every bodybuilder is familiar with causes swelling around the targeted muscles has proven to contribute to muscle growth. The addition of any spare muscle glycogen also helps to swell the muscle and is known as sarcoplasmic hypertrophy causing muscles to appear larger.