In the previous two articles of this three-part series, I talked about training volume (how many total sets you should do each week for each muscle group) and training frequency (how often you should train each muscle group).
In this article, I am going to cover training intensity – how many reps you should be doing for each exercise to optimize muscle growth, and whether you should be training to failure or not on each set.
Some people lift heavy weight with low repetitions, while others lift lighter weights and do more repetitions. And some people take all their sets to complete failure (where you can’t do anymore reps), while others leave a few reps in the tank.
Which strategy makes more sense to maximize muscle growth?
Typical Hypertrophy Rep Range
It has long been thought that you should perform heavy weight with low repetitions in order to gain strength, lighter weight with high repetitions for muscle endurance, and somewhere in the middle for muscle hypertrophy (gaining muscle size).
This is known as the “strength-endurance continuum.”
These options follow the SAID principle (specific adaptation to imposed demand). This principle states that your body adapts to the specific demands you place on it.
So if you lift heavy weights, your body will need to adapt and you will get stronger in order to lift those weights. On the other hand, if you perform high repetition sets (endurance), your body will need to adapt in that specific way, increasing your muscular endurance.
This leaves the middle rep range (6-12 reps) as the traditional hypertrophy rep range, where you can still lift pretty heavy weight, but also perform enough reps to accumulate sufficient volume (total work) to grow your muscles.
While that option might sound like the best of both worlds (strength and endurance) in this article, we will review the research suggesting that the “hypertrophy” rep range might not actually be as definitive as was once thought.
Research on Rep Ranges and Muscle Growth
In order to find out what rep range we should use during our workouts to maximize muscle growth, we need to review the relevant research.
While there are individual studies that could be referenced, the most thorough study to date is a 2017 meta-analysis conducted by Dr. Brad Schoenfeld consisting of 21 studies that examined the relationship between rep ranges and muscle growth.
Assuming training volume (sets x reps x weight) is the same and you are performing your reps close to failure, Schoenfeld concluded that you can actually achieve similar muscle growth across many different rep ranges.
“Although differences in mean ES (p = 0.10) suggest a likely probability favoring heavier load training, study level analysis as illustrated in Figure 4 (above) showed no impact of load (p = 0.56) and the mean percentage gains were comparable between high and low-load conditions (8.3 vs. 7.0%, respectively)”
In other words, muscle growth is not limited to the hypertrophy rep range and the specific number of reps you use isn’t what determines whether you maximize your muscle growth – lower, higher, and medium rep ranges are all effective.
Your main objective should be performing enough volume and taking your reps close to failure in order to optimize muscle growth. Whether you should train to failure or not will be discussed in more depth later in this article.
While there are benefits to doing lower and higher rep ranges, there are also potential drawbacks to sticking to just one rep range.
Benefits of the Strength Rep Range (1-5 reps)
Research shows that the primary benefit of performing reps in the strength range is that you do indeed get stronger with this approach.
In one study, for example, participants performed 3 sets of 7 exercises for 8 weeks. One group performed their sets with 2-4 reps, while the other group performed their sets with 8-12 reps.
After 8 weeks, the participants who performed 2-4 reps showed more strength gains, while the 8-12 rep group showed more muscle mass gains because they were able to accumulate more volume.
Limitations of the Strength Rep Range
On the other hand, one of the main limitations of solely performing reps in the strength range is that you need to perform more sets in order to create enough volume to maximize muscle growth.
I discussed the need to perform enough volume in order to maximize muscle growth in this article that I wrote previously.
When you only do 1-5 reps, you are not putting your muscles through enough “work” to maximize their growth (this is why the meta-analysis mentioned at the beginning of the article needed to account for equal volume between the participants in order to appropriately test which rep ranges are optimal for muscle growth).
In other words, while you might reach failure after just 1-2 reps of a very heavy weight, you are not accumulating enough volume for muscle growth unless you perform a high number of sets, which would be very taxing on the body.
The second limitation of performing too many sets in the strength rep range is that there is greater chance of injury when you are lifting heavy weights, especially as you get older. It is easy to irritate your joints and pull a muscle when you lift heavy weights, a potential risk that should be considered when designing your workout routine.
Benefits of the Endurance Rep Range (12+ reps)
The primary benefit of performing more reps per set is that it allows you to perform more volume. By choosing a weight that is on the heavier side and performing many reps, you put your muscles through metabolic stress, one factor needed for muscle growth.
Limitations of the Endurance Rep Range
That being said, there are some limitations to this approach as well.
First, while you do get stronger performing reps in the endurance rep range, you gain more strength by using heavier weight.
Additionally, performing higher rep sets, especially with compound exercises, is very taxing on the body. For example, if you have ever performed 3-4 sets of 15 repetitions to failure on a back squat, you know what I’m talking about.
For these reasons, performing all of your sets in the 12+ rep range is not optimal.
So What Rep Range Should You Be Doing?
Based on the research presented above, I recommend that you incorporate all different rep ranges into your workout routine.
While you certainly should perform heavy sets if you are able to with good form, dipping into the 1-5 rep range, and lighter sets, consisting of 12+ reps, I would recommend doing the majority of your sets within the 6-12 rep range.
For example, you might want to perform a few sets each workout in the 1-5 rep range (10-20%), a few sets in the 12+ rep range (10-20%), but then the rest of your sets in the 6-12 rep range (60-75%)
The benefit of the 6-12 rep range is that it allows you to still lift heavy weight, while also performing enough repetitions in order to create sufficient volume.
Example Routine
Below is an example of how you can structure an upper body day into your routine to take advantage of all rep ranges.
Bench press: 3×5
Pull ups: 3×5-8
Arnold Press: 3×12
DB Rows: 3×12
Lateral Raises: 3×15
Tricep extensions: 3×12
While this is one example of how to incorporate different rep ranges into your workout routine, there are other ways this could be done. For example, instead of doing a specific rep range for each different exercise, you could cover a range of reps within one exercise.
Here’s an example:
Squats: 3x 4-6, 6-8, 8-10
In this scenario, you are performing 3 sets of legs doing “reverse pyramid training.”
Set one is 4-6 reps, then you would drop the weight around 10%. Set two is 6-8 reps, then you would drop the weight an additional 10%. Set 3 is 8-10 reps. In this case, not only are you dipping into the strength range, you are also in the “hypertrophy” range, allowing yourself to perform more total volume.
There are other ways to create a workout routine, such as undulating and block periodization (something that is typically considered for more advanced lifters who are looking for more variety in their training), but that is a topic for another day.
Final Note: How Close to Failure Should You Train?
First, let’s define what we mean by failure. Reaching “failure” is when you are performing a set and reach a point where you can no longer perform any more repetitions with good form.
While you might think that going to complete failure on each set is beneficial as it puts your muscles through more stress, research does not show the benefits of doing this.
This study looked at participants who performed a 20-week resistance training program, some of whom took their sets to failure and some of whom didn’t. The researchers concluded that there was no difference in muscle thickness between the different groups.
The explanation behind this is that training to failure is extremely taxing on the body and your recovery takes longer. Not only will this hinder your ability to perform well on your next set, it also might negatively impact your ability to recover in time to have an effective next session.
That being said, there is a time and place for training to failure, as well as many factors that will influence the decision of whether to train to failure or not.
Personally, based on the research, I would recommend training 1-2 reps shy of failure on most of your compound movements (push ups/bench press, lat pull downs/pull ups, squats, deadlifts, overhead press, etc.), which ensures you are pushing yourself hard, but not overly taxing your body.
For isolation exercises (bicep curls, tricep extensions, lateral raises, calf raises, etc.), it is perfectly acceptable and likely beneficial to train to failure as these exercises are far less taxing on the body.
Conclusion
While the recommendations in this article are based on current research, your particular regimen should mostly be determined by what works best for you and what you find most satisfying.
In general, I would recommend incorporating reps in all 3 different rep ranges. While the majority of your training should take place in the 6-12 rep range, try to incorporate some heavy loads ensuring proper form, where you fail sooner than 6 reps, in addition to lighter loads, where you fail above 12 repetitions.
This will ensure that you gain the benefits of using a variety of rep ranges and help maximize muscle growth.
I hope you enjoyed this article and learned something that will help you as you move ahead in your training. If you haven’t read my posts about training volume and frequency, you might also find those helpful!
If you have any questions or comments, leave them below and I’ll be sure to get back to you!