Building muscle mass is one of the primary goals of many clients I deal with. Gyms across the world are awash with lifters looking to increase their 'gains'. So when looking to add muscle mass, what are some of the key considerations? Well, fortunately, I have some answers from the very best minds in the industry, courtesy of Alan Aragon's monthly research review: -

Progressive Overload: This is perhaps the key tenet to increasing muscle mass, and one that is universally agreed upon by the leaders in the field: "Progressive overload is the backbone of achieving any training adaptation" (Helms, 2017); "...hypertrophy training still requires an element of progression or the body isn't coaxed to adapt" (Bryan Krahn). Simply put, you are required to increase the demands placed upon the body in order to add more size and strength.
Volume is King: Volume, as it pertains to training, relates to the total work you are performing throughout the week. For hypertrophy, increasing volume over time is extremely important. Spreading the volume over several sessions throughout the week seems to be more effective than trying to cram all the work for a certain body part into just one session: "We know that doing too much volume in a single session degrades the quality of work and subsequently the magnitude of adaptations. This is logical, and it has implications for increasing frequency once volume reaches a point where individual sessions become pumping iron marathons" (Helms, 2017). Be careful not to add too much volume too soon, as this may actually backfire and slow the rate of progress. So only add more volume when needed.

The pursuit of muscle used to be confined to bodybuilders. Nowadays gyms are awash with members looking for maximal 'gainz'.

But Don't Forget Intensity: 'Intensity' here relates to the load on the bar. More specifically, the percentage of your 1RM you are lifting with. Hypertrophy gains can be made with a very wide spread of intensities, but sets in the 6-15 rep max (RM) range are probably the most time efficient. For example, if you utilise very low rep work, such as 2 or 3 reps, you would need to perform a lot of sets in order to build up a sufficient amount of volume than if you use slightly higher rep ranges. There is emerging evidence showing that heavier loads target type II fibres (fast twitch) and lighter loads target type I fibres (slow twitch) - "Accordingly, varying repetition ranges has the potential benefit of maximising hypertrophy across a spectrum of fibre types, which will in turn maximise whole muscle hypertrophy" (Schoenfeld, 2017).
Variety is the Spice of Life: Providing an element of variety to your program will be important for various reasons. One reason is purely interest. Motivation for a given program can start to wane if nothing is changed after several weeks. Also: "after receiving a very similar stimulus for months on end, nearly all studied physiological systems develop a resistance to further adaptations" (Godbee, 2017). I think it is good to maintain some elements of a program from one phase to another but there are many variables you can manipulate, including exercise selection, rep range, proximity to failure, lifting speed (tempo), rest periods, load on the bar etc.
De-Load for Continued Progress: "The body can only take so much before you break yourself down: therefore back off weeks are critical to reset, take an 'active' rest and change up gears" (Ashman, 2017). De-loads usually come in the form of a week in which load and/or intensity are reduced to allow fatigue, which has been progressively increased over the previous weeks, to dissipate. De-loads can either be pre-planned (i.e. every 4-5 weeks), or can be self-selected. Carter (2017) explains: "Im not big on pre-planned de-loads. What I prefer to do is let the lifter self-assess where he or she is each training session, each week, and each month". The goal, as stated earlier, is continued progressive overload, where the lifter is continually progressing with more and more weight on the bar. However, as the lifter becomes increasingly experienced, it becomes impossible to make progress in a linear fashion. So, using planned periods of over-training (or 'over-reaching'), combined with de-load weeks, can reap greater rewards. "Programming in a manner that keeps the individual physically healthy and in the gym is going to yield superior long-term results than the program that pushes the individual to their limits but injures them and takes them away from training" (Godbee, 2017).

So there you have it. The best minds in the industry supplying you with the need to know information when it comes to increasing muscle mass.