You can find many variables which affect your muscle growth. Scientists and coaches try to examine them and give us better tips for working out.
Among these factors are the number of repetitions (reps). You can work out in different ranges of repetition which can significantly impact your athletic achievements.
Many gym-goers think that low repetitions are suitable for strength and muscle building while high repetitions are only for endurance. However, I would like to say that they both could be useful for muscle hypertrophy.
In recent times, I’ve read many interesting and different opinions about this topic. Today, I want to share my discoveries and experience with you.
What is a repetition?
We can define repetition as one complete movement of a particular exercise. You grab dumbbells from the ground and curl them on biceps or press from shoulders once. In both cases, you have performed one repetition. Repetitions help you to count the number of exercise movements. For example, 8 repetitions of bench press or 10 repetitions of a squat. Most gym-goers count how many repetitions they perform in one set.
Repetitions along with sets, rest intervals, resistance etc. are the factors that directly affect your training intensity. For example, to calculate so-called volume load, we use the equation such as repetitions x sets x resistance kg.
Even for repetitions there are some classifications. It helps to better understand the intensity of the load. Usually, reps are classified as:
- 1 – 5 heavy
- 6 – 14 medium
- 15+ light
Rep ranges are related to a percentage of the maximum weight that you can lift one time – one repetition maximum (1RM). For example, if you decide to work out with heavy loads over 85 % of 1RM, then there’s a greater chance that you will do 1 – 5 reps. The lighter the weight you choose, the more reps you will do. In a workout, we can use either reps or % of 1RM to determine the intensity of the load.
Different opinions for the best rep ranges for muscle hypertrophy
One of the most popular recommendations is to do 8 – 12 reps for muscle hypertrophy. Did you know that the origins of this advice dates to 1954? It comes from English surgeon and bodybuilder, Ian MacQueen. During that time, he proposed 8 – 12 rep ranges as the best choice for muscle growth and it is still very popular nowadays.
In more recent times, Arnie suggested performing 8 -12 repetitions for upper body, but 12 – 16 repetitions for lower body in his bodybuilding encyclopedia. He argues that your lower body doesn’t fatigue as fast and for this reason you should perform more reps.
Trainer of champions, Chris Aceto, in general, argues for 6 – 12 repetitions. Meanwhile a man with an amazing physique, Jeff Willet, advertising MAX-OT training systems, stands at only 4 – 6 reps for muscle hypertrophy.
Ah! People and their opinions are so different.
In the following sections, we’ll try to explore the latest studies and theories about rep range impact on muscle growth.
7 – 40 seconds for muscle growth
And now I want to sift through some theories for muscle building which suggest the best rep range selection.
In order to boost muscle growth during a workout, we should affect muscle cells (fibers) in a certain way. As I’ve mentioned in the introduction, many factors come into play for building muscles.
According to scientific resources, the repetitions range should last from 7 to 40 seconds or even better from 15 to 40 seconds. It’s the so-called hypertrophic range. During this time frame, muscles get optimal stimuli for growth. If your reps last less than 7 seconds, the stimulus will be insufficient. On the other hand, repetitions over 40 seconds don’t activate enough muscle fibers. It’s also bad for muscle building.
Actually, this is related to the main energy molecule adenosine triphosphate (ATP) production pathways: phosphagen – energy from creatine phosphate; glycolytic – energy from glucose. The optimal hypertrophic range is from the point when phosphagen reduces to about half but the glycolytic pathway just starts to dominate. It creates the appropriate environment for muscle growth. Usually, this happens (occurs) during the 7 – 40 second window.
However, I would like to repeat one more time that this is only a theory.
What studies reveal to us?
Now, you know some theories about how long your repetitions should last. Let’s look closer at what a few studies reveal to us.
Usually, I like to look at meta-analyses, because they provide us with the most complete information.
I found one meta-analysis that examined data from 140 studies about the optimal workout intensity for strength gains.
What were the main conclusions?
Newbies gained more strength doing exercises with the mean intensity 60 % (around 8 – 12 reps) of 1RM. Meanwhile, for the more seasoned individuals, the best choices were 80 % (around 4 – 6 reps) of 1RM. In the first instance, it seems that we found the answer and need to stick only to this rep range. However, there are two problems.
Firstly, among persons and even exercises, there is a variation of how many reps you can perform with a certain weight. For example, one related study found that working out with a weight of 80 % of 1RM resulted in 10 reps for bench press, 7 – 8 for the bicep curl and 15 reps for legs press. The difference is significant. I suppose if you exercise for a long time, you have already noticed that. For this reason, it is difficult to predict how reps correlate to % of 1RM.
Secondly, this meta-analysis focused only on strength, not muscle gains. We are more interested in maximizing hypertrophy.
We can look to the other studies, which focused exactly on rep range impact on muscle growth. I found 5 studies which analyzed this question and I collected data from them.
As you can see in the table below, either a low, medium or high repetition range resulted in similarly gained muscle mass. Strength increased better during low and endurance high rep range.
A very important remark from experts is that to get a similar effect from all repetitions, you should equate volume. It means if you perform 3 sets of 8 – 12 reps, you should perform 4 – 5 sets of 3 – 5 reps to get the same workout volume.
How can low reps affect your muscle hypertrophy?
For muscle growth, it is very important to gradually increase your working weight over time.
Low reps help you to gain strength and further work outs with heavier weights in a hypertrophy repetition range. Strength training could also become a new challenge in your everyday workout routine.
Be ready as some of you will experience better growth on pure strength workout.
How can high reps affect your muscle hypertrophy?
On the other hand, we have high reps.
I suppose you know that we usually talk about two types of muscle fibers: slow and fast twitch. Increase in muscle size mainly comes from fast-twitch muscle fibers. For this reason, gym-goers focus on their development. However, slow-twitch muscle fibers can also help to increase muscle size. Some people tend to have more slow-twitch muscle fibers than others. In order to increase slow-twitch muscle fibers, you should exercise in the high rep range.
A number of mitochondria and capillary density in your muscles can also positively affect their size. High rep range is that what you need to increase both of them!
What is the best choice?
If you get confused by this information overload, I want to give you some guidance.
I would like to start with the easiest part – newbies. Newbies should utilize only medium to high reps: 8 – 20. Because they both boost muscle growth and would be more proper for leaning towards correct exercise form.
For more advanced… It seems to be better to work out during a wide rep range like 1 – 20. Periodically, change your reps from lower to medium and higher. Yes, I can agree with Chris Aceto that on average, you should work out in the 6 – 12 rep range. However, stick to the reps which give the best results for you for maximum muscle gains, either 5, 10 or 25! l leave it as your choice. The most important factor is to get positive results!
For exercises with a relatively short range of motion, go for more reps than for exercises with a longer movement amplitude. This is because they take less time to perform. For example, one rep for a calf rise is less time consuming than the squat.
Which of rep range do you prefer?
- A meta-analysis to determine the dose response for strength development.
- Differential functional adaptations to short-term low-, moderate-, and high-repetition weight training.
- Effects of different volume-equated resistance training loading strategies on muscular adaptations in well-trained men.
- Effects of Exercise on Mitochondrial Content and Function in Aging Human Skeletal Muscle.
- Effects of Low- Versus High-Load Resistance Training on Muscle Strength and Hypertrophy in Well-Trained Men.
- Gross measures of exercise-induced muscular hypertrophy.
- Muscular adaptations in response to three different resistance-training regimens: specificity of repetition maximum training zones.
- Neither load nor systemic hormones determine resistance training-mediated hypertrophy or strength gains in resistance-trained young men.
- Relationship Between Repetitions and Selected Percentages of One Repetition Maximum.
- The relationship between the number of repetitions performed at given intensities is different in endurance and strength trained athletes.