It’s one of the most discussed topics among gym goers: how many reps should you do for optimal muscle growth (hypertrophy)?
The answer: almost any rep range is effective for muscle growth, as long as you train your sets to muscle failure or near-muscle failure (1-3 RIR). However, there is a rep range that is preferable for the average bodybuilder, namely 6 to 15 repetitions.
Coach Bill Campbell shows that this is supported by various studies: 7 sets of 3 reps are no better than 3 sets, 20-25 reps per set is no different than 8-12 reps per set, 3-5 reps per set is not different from 10-12 reps per set and 2-6 reps per set is no different than 6-12 reps per set .
However, a good coach will not arbitrarily prescribe every rep range:
- If you want to lift heavy most of the time (< 5 reps per set), you may need to do more sets to get enough volume needed to cause muscle growth. See also this study. Low rep ranges are more effective for strength gains;
- If you want to lift lighter weights most of the time (15-20+ reps per set), then you have to accept experiencing more pain and discomfort than with a medium-rep range, say 8 to 12 reps. One study reported that the feeling of discomfort was significantly higher at approximately 20 repetitions per set, compared to 10 repetitions per set;
- Several coaches, including Bill Campbell and also Brad Schoenfeld, advise using different rep ranges for each muscle group. See also this article. This way you can be sure that each muscle group receives sufficient growth stimuli. You may also appeal to the two types of muscle fibers that exist, but more research is needed for this.
Campbell uses the following method for most of his clients: 2-6 repetitions (20%), 8-12 repetitions (60%) and 15-20 repetitions (20%).
In principle, any rep range is sufficient for muscle growth, but very low ranges (< repetitions per set) or very high ranges (> 20 repetitions per set) have their specific disadvantages and may therefore not be optimal.
Therefore, use a medium rep range for most of your training: 6-15 repetitions (possibly broken down to 6-10 for compounds and 10-15 for isolation exercises). Supplement that with some sets of 2-6 reps and 15-20+ reps.
Always train your sets to near muscle failure and perhaps some to complete muscle failure.