To build muscle fast you need to present the body with a stimulus that it isn’t used to. This stress will cause the body to adapt by building itself up bigger and stronger.
Where most people go wrong is that they think they need to annihilate the muscle in order to elicit any type of response. This is counterproductive. When you annihilate the muscle with tons of sets, reps and constantly train to failure and beyon you drastically increase your recovery time. The problem with that is that training frequency is very important. So when you increase your recovery time you have to decrease your training frequency. You’re shooting yourself in the foot.
The key is to do just enough to stimulate size and strength gains but not annihilate yourself so that it takes forever to recover, or worse- that you put yourself in a state of overtraining.
If you want to make consistent size gains you have to make consistent strength gains (in a hypertrophy rep range), while eating enough food and allowing enough time for recovery.
The body will respond to any given stimulus one time and one time only. If you place the same demands on it a second time (like pressing the same weight for the same reps) nothing will happen. You must always be forcing it to adapt and thus you must always ask it do something it isn’t used to.
The easiest way to do this is add more weight or do more reps with the same weight (but no more than 10-12 for the upper body and 15-20 for the lower body).
Aside from making consistent strength gains the next most important thing to consider is training frequency. To improve anything in life you need to do it frequently. Building muscle is no different.
So you want to train a muscle as frequently as possible, while it is in a fresh and recovered state. This means that you should be training each body part once every 2-5 days, and not once a week like a lot of the muscle mags recommend. That’s too little frequency. The more times you can stimulate growth throughout the year the better. Obviously 104 growth stimulating workouts per year for each body part would be a lot better than 52.
Summing it up, to build muscle fast you need to do the following three things:
– Constantly get stronger.
– Stimulate but don’t annihilate (12-16 sets per workout. Don’t go to failure)
– Train each muscle group more frequently than once per week.