To most people the muscle-building process is ostensibly self-explanatory. You exercise, eat right, rest, and sooner or later you’ll look like Arnold in the 80’s. Of course, you don’t need a science teacher to tell you that there is a lot more going on internally. If you’d like to know more about how the body builds muscle, without taking a collegiate course in biology, check out our simplified guide below:

The Break Down Before the Build Up

In order for muscles to build strength and mass the tissues must be exposed to microtrauma, either through repetitive motions or resistance training. Although it is necessary to overload the muscles to an extent, there can be a fine line between beneficial exhaustion and detrimental injury. Workout duration, frequency, intensity, and technique all play important an important role in determining whether you’re promoting optimal growth or facilitating gradual deterioration.

The wrong type of movement done repetitively could decrease your range of motion or put harmful pressure on your joints. The old saying “what doesn’t kill you makes you stronger” doesn’t always apply to bodybuilding, as you can make many non-fatal exercising mistakes that will only result in you getting weaker.

Nutrient Assimilation and Repair

When muscle fibers are torn the body sends increased blood flow to the area, initiating a process known as phagocytosis, in which phagocytes – white blood cells -- dispose of the damaged cells. Once most of the damaged cells are gone the body sends a surge of progenitor cells, which attach themselves to the muscle in an effort to protect the same tissues from being damaged again. With sufficient protein synthesis and the presence of adequate hormone levels (mainly testosterone) the progenitor cells will actually become part of your muscle, leading to growth and increased strength.

The body needs protein, carbohydrates, and trace vitamins and minerals to effectively rejuvenate and rebuild itself. Depending on the intensity of your exercise regimen you should be consuming 1.0 to 1.5 grams of protein per pound of body weight each day. So if you weigh 150 pounds you should be getting about 150 to 240 grams of daily protein. Here are some helpful resources that will give you more detailed protein and calorie requirements based on your lifestyle and training goals:

Protein Requirement Calculator

Calorie Requirement Calculator

Muscle Maintenance

Once muscle is built the body uses various mechanisms to ensure that it does not deteriorate, so long as your daily caloric intake is sufficient. If you don’t meet your minimum protein and calorie requirements your body will start to consume resources from within. If you’re inactive and have a low percentage of body fat then you’ll probably lose muscle faster than an inactive overweight person who doesn’t get enough calories (as they have larger reserves than a slender person). In all cases, strenuous activity without adequate nutrition and rest will result in a loss of muscle density and tone – a common outcome of overtraining combined with improper diet.

Sergio Martinez is a fitness professional and former bodybuilder who has spent a lot of time studying the nutritional requirements for building and maintaining muscle.