Everyone is so obsessed with all of the specific principles in the gym (such as exercise selection, rep ranges, which days to spend in the gym, how many sets to perform etc.) that they fail to see the big picture.
Regardless of what type of approach you are taking in the gym, the underlying factor for success is progression.
Our bodies build muscle because of an adaptive response to the environment. When you go to the gym, you break down your muscle fibers by training with weights. Your body senses this as a potential threat to its survival and will react accordingly by rebuilding the damaged fibers larger and stronger in order to protect against any possible future threat.
Therefore, in order to make continual gains in muscle size and strength, you must focus on progressing in the gym from week to week in order to consistently increase the stress level.
Progression can take 2 main forms:
a) Increasing the amount of weight lifted on a specific exercise. b) Increasing the number of reps performed with a given weight on a given exercise.
If you’re able to improve on at least one of the above factors each week in the gym, your body will be given continual incentive to grow larger and stronger.
If you neglect these factors and enter the gym without a concrete plan in mind, you’ll be ignoring the very foundation of the entire muscle growth process, and your gains will surely stagnate.