Volume & Training Frequency. How Much Exercise Is Really Enough?
Taking into account physiology and all other aspects of exercise, it becomes clear how much (volume) and how often (frequency) you should be training.
Progressive Overload, Progression, Adaptation & Variation
Progressive overload is the process of gradually increasing stress loads, pushing your body beyond its comfort zone by overloading your physical systems.
Periodization & Cycles
Periodization and cycles have become an important principle for continuing progression, and to ward off stagnation, boredom, and burn-out.
Rest Periods
While exercise with short rest periods will generate high metabolic stress, short rest periods might not be as useful for developing strength or power.
Recovery
There isn't a 'one size fits all' for recovery time, but the general consensus is about 48 hours of recovery time per muscle group after exercise.