Outlined below are three basic principles of muscle-building success. They seem obvious when written down on paper but nonetheless are the areas where most people fall short.
Progressive Overload - There is no two ways around it. You need to give your muscles a reason to grow. The only way to do this is by progressively increasing the physiological challenge they must overcome. This can be done by steadily adding repetitions and resistance to any given exercise. This process takes time. You need to workout, recover, come back stronger, upgrade the challenge and repeat. The biology cannot be rushed.
High Calorie Intakes - Progressive overload provides the stimulus. Now it’s time to fuel the growth. Without high energy intakes, particularly for ectomorphs like me, the body simply won’t have the reserves it needs to build significant volumes of muscle. A couple of summers ago I did a bulking up experiment and the amount of food I needed to eat was frightening, tiresome and ultimately cannot have been good for me. However if success is judged purely on getting bigger then it did work!
(If you just want to improve your muscle to fat ratio without adding new atoms/mass to your body then really high calorie intakes are not so important. Focus instead on resistance training, progressive overload and a sensible quantity of nutritious foods.)
Plenty Of Sleep - To complete the loop and tie everything together it is important to get lots of high quality sleep. This is when the majority of repair and regeneration occurs across the body, muscles included. Better workouts, better food choices, better recovery. Without this key ingredient the whole muscle-building process becomes much more of a struggle.
To Sum It Up
Perform resistance exercises, make them harder over time, eat lots of nutritious calories and prioritise sleep. Simple! As usual it is consistency which presents the toughest hurdle.