For most gym-goers, it almost goes without saying that if your goal is to build the most muscle possible, then ALL your training MUST be done in the 8-12 rep range; no less & no more. To be fair, this is an incorrect statement, but it also holds some truth. Allow me to elaborate.
Yes, training using 8-12 reps will allow you to build muscle. However, what it will not do, is maximize your muscle building potential, if all you do is stick to that range exclusively. It is important to understand that hypertrophy training (training with the goal of building muscle) is not specific to any repetition range. Research has shown that training using low reps (1-8), moderate reps (8-12) and high reps (12-20+), will ALL result in muscle growth.
Low repetition (1-8 reps) training will necessitate that you are training using heavy loads, which will maximally recruit your fastest twitch muscle fibres. These are the muscle fibres in your body that have the greatest capacity for growth! More so, training in the 1-8 rep range will dramatically increase your strength. Simply put, your nervous system becomes particularly efficient in recruiting and activating your muscles in the most coordinated fashion possible, in order to execute a given lift e.g. the bench press. Therefore, the strength gained using low rep training will allow you to use much heavier weights in both the moderate and high repetition ranges, allowing you to generate an even greater tension stimulus, recruiting and damaging more muscle fibres, which will in turn, grow even more muscle.
Moderate repetition (8-12 reps) training, is not magical in any sense when it comes to maximizing muscle hypertrophy (muscle size). All it is, is a practical solution to those that either don’t care about maximizing their results, or are just oblivious to the reality that they actually can. Moderate reps allow you to lift heavy enough weights to generate a sufficient tension stimulus for growth. Also, because the weight used is not that heavy, it becomes much easier to perform a greater number of sets in a single session, without becoming overly fatigued. And the more sets you can perform, whilst still being able to progress in your training and being adequately recovered, the more muscle you will grow, generally speaking.
Lastly, high repetition (12-20+) training, most people think is reserved only for populations seeking increases in muscular and cardiovascular endurance. This could not be further from the truth. Anyone that has trained their arms using repetitions as high as 15 or even 20 reps to failure, can attest to the intense burning sensation that one experiences when lifting in this fashion. This is caused by an accumulation of lactic acid within the muscles. Lactic acid is a metabolite that has been theorized to aid muscle hypertrophy. Meaning, the more metabolites we can saturate our muscles with, the better. In addition to that, the skin tearing pumps you get from high rep training is out of this world. This cell swelling response has also been positively correlated to increases in hypertrophy. Finally, load and repetitions are inversely correlated. The higher the reps you train with, the lighter the weights you will be using and vice versa. Light weights significantly decrease your risk of injury, most often brought about by lapses in proper training technique, most often seen in lifters that train using heavy weights and poor lifting form. Building muscle is a marathon, not a sprint. You can’t get jacked if you are injured, so best to avoid/prevent it.
Hopefully you can now see that there is more to building muscle than just training using 8-12 reps. There are countless ways of skinning this cat, and all the reps listed above are tools in your tool belt that can and should be used as and when necessary in order to truly maximize your results.
So…..what rep range is the “best” for building muscle?
The answer, you should now know, is all of them.