Continue to progressively overload the targeted muscle group or energy system, and you will continue to improve... for a little while.
Fail to properly modify your volume, intensity, and/or rest, and you will likely experience the dreaded plateau
Intelligent manipulation of training variables (volume, load, intensity) results in just the right amount of overload to elicit an appropriate stress response. Continue to increase the volume and/or intensity over time -- this is called "progression."
In order to ensure proper progression, you must systematically and intelligently modify the Volume, Duration, Intensity, and Rest Time for the work you intend to perform.
This concept is closely associated with the General Adaptation Syndrome -- with an incremental, progressive approach to increasing volume and/or intensity, we take advantage of our knowledge of the G.A.S. and continue the gains.
WHAT VARIABLES CAN I MODIFY?
systematic manipulation of volume and intensity at specific time intervals to bring about optimal gains
intelligent modification of exercise parameters and training stimulus - this is the nexus of the principles of overload, progression, and recovery.
optimize positive adaptations to training and "peak" at the appropriate time
Han's Selye's G.A.S.
(General Adaptation Syndrome)
HOW TO INTEGRATE THESE CONCEPTS
What are macro, meso, and micro-cycles?
Phases of progression are often described in terms of cycles. Depending on the type of athlete and the sport an athlete is involved in, macro-cycles can last up to 4 years (think Olympic athlete). That means that the athlete's training plan is focused on peaking somewhere around the Olympics every four years. Each year of that athlete's training might be described as a meso-cycle (just a period of time between the macro and micro). The athlete's meso-cycle is then further divided into micro-cycles -- something like the phases described above.
How long can I stay on a linear progression?
Hate to say it, but it depends... what is your training age? Truth is, if you're still reading this, and you are not a competitive power lifter, then you probably have not maxed out your linear progression potential. With a moderate approach and well-timed deloads, you could live on 3x5 island for years.
What is a de-load?
Big word, simple concept. Periodization describes the manipulation of variables to ensure that performance trends upwards without providing so much stress that we lose those hard-earned gains. The de-load is a staple of well-planned training - it gives the body some time to super-compensate (recover and grow). De-load by decreasing your volume and/or intensity and increasing your rest/recovery time. De-loads often last about a week and occur between cycles or phases of training.