What is the best rep range for building muscle?

4-6? 8-10? 12-15? 20-25?  

There are so very many opinions out there on where your rep scheme should fall if your goal is to build muscle. But what is the truth? If you are trying to build muscle, what rep scheme should you be focusing your time on? 

First, we need to start with determining how we build muscle. The amount of muscle growth or hypertrophy we achieve is determined by a few things. Volume (the overall amount of weight/tonnage lifted during a workout), and intensity (how difficult or how much effort was exerted during a workout). 

Volume is determined by (pounds lifted) x (number of reps) = tonnage. Say you have a bench press set at 185lbs x 8 reps for 4 sets. This is going to be 185x8x4. So, this results in 5,920lbs lifted during your bench press movement.  

You would do the same for each movement in the workout. This is going to determine the overall tonnage lifted during the entire workout. Which is going to be the main driver of muscle growth.  

But you also need to make sure that you are achieving a high enough intensity level during that workout. The process muscle protein synthesis is stimulated more, the harder the body is forced to work to complete said workout. The more we can stimulate MPS, the better chances we have at building lean muscle.  

So, we need to make sure that bench press of 185 pounds was difficult enough to only leave 2-3 reps left before technical failure (the point at which form breaks down) on each set. Or a 70-80% exertion level, EACH AND EVERY TIME! 

Ok great! But what about the best rep scheme to achieve the most muscle growth possible? Should you just work at 4-6 reps to make sure you are lifting the most weight possible, or should you be lifting lighter weights in the 12-15 rep range. After all hypertrophy is all about how many times I move the weight, contracting and extending the muscle. Right? 

While yes, hypertrophy is stimulated by the repeated extension and contraction of the muscle. If your goal is to maximize gains, you should not be locking yourself into any one rep range.  

You should be working through all the different rep ranges to maximize muscle gain as well as strength gain. If you only ever work in the 8-10 rep range, you will only ever get good at the 8-10 rep range. Likewise with 4-6 and 12-15 and any other rep range for that matter. This is the principle of specificity. What you train is what you get good at. 

So, if your goal is to look as good as possible while also being as strong as possible (naturally). You need to be orienting your workouts to take you through the full spectrum of rep ranges. Everything from super heavy 3&5s to light 20s & 25s. Even the occasional 1 or 2 sets of 50 reps meant to just pump as much blood to the muscle possible.  

Train at all the rep ranges so you can get good at all the rep ranges.