It’s a question of the ages: what rep range is best for building muscle? Before we begin, let me dispel a widespread myth. I often hear about the merits of sarcoplasmic versus myofibril hypertrophy. However, common knowledge on bodybuilding forums often does not always align with reality:

          Sarcoplasmic vs. Myofibrillar hypertrophy? Perhaps you’ve heard those terms and even read information from some guru who says there are different types of ‘hypertrophy’. This is unadulterated garbage and anyone who has ever taken a course in muscle physiology, exercise physiology, or knows a little biochemistry would tell you so. There are no examples of where a muscle fibre hypertrophies with resistance training and the myofibrillar pool doesn’t grow but the sarcoplasm does.
          The next time you hear someone spouting off about sarcoplasmic hypertrophy you can tell them that no such thing exists. It’s a construct of bodybuilding forums. Hypertrophy is hypertrophy and strength is strength.
          -Stuart Phillips, Kinesiology PhD

I reckon this myth came about from observing the neural components of strength: feats of strength performed with relatively little muscle tissue. Ever seen those videos of a small-looking guy lifting a staggering amount of weight? Through neural adaption your body “learns” how to more efficiently fire the motor units located in your muscles. This process is also how new lifters gain surprising amounts of strength in the first few weeks of training.

In 2010, researchers from McMaster University of Ontario compared the muscle growth elicited from high-rep/low-weight programs to that of low-rep/high-weight programs. The study raised quite a ruckus when the  results showed that a workout performed at 30% 1RM stimulated an equal post-workout response as workouts performed at 90% of 1RM. Both routines were performed until muscular failure.

The low weight/high rep program elicited greater myofibrillar protein synthesis rates than the heavy weight/high rep condition, measured 24 hours post-workout. These results would suggest that higher-rep ranges using lighter weights results in greater muscle growth than going heavy with lower reps, which immediately set bodybuilding forums and magazines abuzz.

You’ll see studies similar to this one thrown around the internet fairly frequently, however, separating useful information from the chaff is an important skill if you are looking to optimize your training.

Do not make the mistake of applying information from short-term studies into your long-term routine. The study listed above only looked at muscular growth 24 hours post-workout. It’s important to read the methodology of studies before leaping to conclusions. A variable that elicits higher growth 24 hours post-workout does not necessarily translate into a wise practice long term. Be vigilant with your skepticism, dear readers.

So, what Rep Range is Best for Building Muscle?

Current studies indicate that a mixture of both high and low rep ranges returns greater muscle growth than focusing on either in isolation.

To maximize muscle hypertrophy, an optimal workout should include both high and low rep ranges.

To reap the best of both worlds, use strength-focused lower rep ranges on compound lifts such as bench press, deadlift, chin-ups, etc. The higher rep ranges should be used on the various accessory movements in your routine (such as bicep curls, tricep pushdowns, etc).

The takeaway:

  • A mix of both high and low rep ranges is best for optimal muscle hypertrophy.
  • Use strength-oriented low rep ranges (5-8 reps) on your compound movements.
  • On your accessory lifts, aim for a higher rep range (8-12 reps)
    • Muscle groups composed of primarily slow-twitch fibers, such as deltoids or calves, may respond best to a slightly higher rep range (10-15 reps).

If you’re interested in a routine that makes use of these principles, you can find one here.