When it comes to lifting weights and gaining muscle mass, making sure you hit the right rep range is deemed very important. In this article I will summarise some of the research into what is the best rep range to build muscle.
The chart below is what most people and coaches, including myself, have used to set the appropriate rep range depending on the goal.
The Chart shows the number of reps and weight of the load for:
- Strength training – 1-5 reps heavy load
- Hypertrophy (increase in size of muscle mass) – 6-12 reps moderate load
- 13-14 reps – no man’s land, avoid at all costs as the universe will explode.
- Endurance – 15+ Reps light load – Also known as cardio to bodybuilders.
Based on this information the ideal rep range for putting on muscle mass is 6-12 reps. If you go any lower than 6 you will turn into a power-lifter or higher than 12 and you will lose all your gains and turn into a endurance athlete.
However, recently there has been more research into which rep range and load produces the most amount of muscle hypertrophy. Brad Schoenfeld has conducted much of this research. Brad is one of the go-to coaches and researchers when it comes to muscle hypertrophy.
In his article ‘THE MECHANISMS OF MUSCLE HYPERTROPHY AND THEIR APPLICATION TO RESISTANCE TRAINING’, he outlines the 3 main mechanisms for muscle hypertrophy:
- Mechanical Load – this is when large amounts of mechanical force and tension are generated and applied to the body’s muscles and joints through resistance training. Basically means lifting heavy weights.
- Metabolic Stress – this is the build up of metabolic waste products from anaerobic respiration. This is what causes the burning sensation in the muscles, or what Arnold Schwarzenegger refers to as the pump.
- Muscle Damage– exercise training can result in damage to muscle tissue, this is known as Exercise-Induced Muscle Damage (EIMD). This however is not to be confused with the Delayed Onset of Muscle Soreness (DOMS). DOMS is a by product of EIMD, but EIMD does not always cause DOMS. Therefore don’t go searching for soreness every-time you train, as this will only be detrimental.
What does the research show to be the best rep range to elicit these 3 mechanisms for muscle hypertrophy? To help answer this question I recently attended the Personal Training Collective Conference in Bath where Brad Schoenfeld was one of the speakers. One of his topics was ‘Loading Zone – Implications for Strength and Hypertrophy’. The research Brad showed us looked at comparing different loads and rep ranges and their effect on muscle hypertrophy. In my article I have summarised the research that Brad showed us as well as other research on the same topic of muscle hypertrophy and loading zones.
Research Into Loading Zones And Muscle Hypertrophy
A study by Schoenfeld et al randomly assigned 17 resistance-trained (4 years experience) individuals into 1 of 2 groups.
- The 1st group was a Bodybuilding group who performed 3 sets of ~10Rep Max (RM) using split routine with 90 sec rest intervals.
- The 2nd group was a Powerlifting group who 7 sets of ~ 3RM using total body routines with 3mins rest intervals.
Training was performed 3/week over 8 weeks. The findings showed that:
- There was a similar increase in Bicep Thickness between groups.
- The Powerlifting group significantly increased their squat and bench 1RM compared to the bodybuilding group.
The findings suggest that hypertrophy can be achieved equally through heavy or moderate loads in well-trained subjects. However 2 people pulled out of the powerlifting group due to injuries. The bodybuilding type routines took a ¼ of the time to perform with similar results in the regards to hypertrophy. And the powerlifting group were more fatigued after each training session.
Another study by Klemp et al 2016 found similar findings when looking at increases in muscle hypertrophy in the quads and pectorals in 16 resistance trained individuals using moderate load of 8-12 RM and heavy load of 2-6RM.
In these 2 studies the volume and load were equated between groups.
Mangine et al 2015 (5) compared different rep. ranges where the loads were non-equated between groups. 29 resistance trained men were put into 2 groups.
- 1 group performed 4×10-12RM with 1min rest between sets.
- The other group performed 4×3-5RM with 3mins rest over an 8 week period.
The findings showed there was a greater increase in lean arm muscle mass in the low rep group. 1RM for the bench press was greater in the low rep group as well. This may be because the loads were non equated and the low rep group lifted more weight overall.
Campos et al 2002 (5) looked at 32 untrained individuals and compared 3 different resistance training regimes. Subjects were divided into 4 groups:
- Low rep group 3-5RM for 4 sets, 3min rest
- Intermediate rep 9-11RM, 3 sets, 2min rest
- High rep group 20-28RM, 2sets, 1min rest
- Non-exercising control group.
Three exercises (leg press, squat, and knee extension) were performed 2 days/week for the first 4 weeks and 3 days/week for the final 4 weeks. The findings show that the low and intermediate rep groups induced similar muscle hypertrophy responses, whereas the high rep range didn’t. The low reps group significantly increased strength compared to the other 3 groups.
The practical application from these studies:
- Both heavy and moderate loads produce similar levels of hypertrophy.
- A bodybuilding style program is more time efficient than a powerlifting style program.
- The bodybuilding style programs are shorter and cause less fatigue. This therefore may lead to additional volume been added and overall gains being achieved. There is also a lower chance of sustaining an injury in a bodybuilding style program.
- Heavy loads significantly increase strength compared moderate to light loads.
Only 1 of the studies listed above, Campos et al 2002, compared heavy and moderate loads to low loads. Previous guidelines in regards to muscle mass gain suggest that you need to be lifting heavy to moderate loads for muscle hypertrophy (65%+ RM). However bodybuilders, who spend most of their time trying to increase muscle mass, will quite often lift in the higher rep ranges 20reps + or 65%- RM. The science behind this suggests that lifting in a higher rep range will increase the size of the Type 1 muscle fibres and lifting with a moderate and low rep range will increase the size of Type 2 muscle fibres.
Therefore what does the research show when comparing high loads to low loads? A meta-analysis conducted by Schoenfeld et al 2014 looked at 8 studies comprising of 191 subjects in total. They found that both high and low loads produced significant growth but there was greater growth in the heavier loads. However a limitation of the meta-analysis was that all the subjects were untrained.
This study by Schoenfeld at al 2015 (6) then compared low v high load resistance training on 18 trained subjects with over 3 years resistance training experience. They were assigned into 2 groups; a 10RM group or a 30 RM group. The subjects trained 3 days a week for 8 weeks. The hypertrophy results were similar between both groups and the high load group had greater increases in strength in 1RM bench press and 1RM squat.
Take Home Message
The research in this article suggests that if you want to increase muscle mass then train through a wide spectrum of rep ranges with heavy, moderate and light loads. Also on an individual basis I have noticed that my clients will respond differently (in terms of hypertrophy) to the same reps ranges.
Training Methods For Muscle Hypertrophy
There are many ways to train through a wide spectrum of reps ranges. One is through block periodisation where you split phasing of training, usually into months. For example 1st month you train through an endurance rep range (15+), second month hypertrophy (6-12) and then third month strength (1-5).
You could also train a different training goal each week. E.G. Week 1 – Strength, week 2 – Hypertrophy and week 3 – Endurance.
Another method that I use myself and with clients is more of a Conjugate System where you train heavy, moderate and light loads in 1 session. Below is an example of an upper body sessions using a conjugate method:
A.1 Bench 4x5reps
A.2 Chest Supported Row 4×5
B.1 DB Military Press 3×10
B.2 Pull Ups NG 3×10
C.1 BB Bi Curls 3×15
C.2 Ez Bar Skull Crushers 3×15
It’s all about finding out what works best for you and not sticking to one rep range. There is not one best rep range when it comes to hypertrophy.