In the previous blog post, we’ve looked into training volume and muscle growth. The main takeaway was that training every muscle group with about 10-20 sets per week is a good starting point for muscle growth. But as you can imagine, just how many plain “sets” you do is not the only thing that is relevant. The intensity of the sets matters as well.

That’s why in this article, we will look into training intensity. Specifically, two types of intensity:

  • The intensity of load (a.k.a. your rep range)
  • The intensity of effort (how close you train to failure)

At the end of this article, you will have a clear idea of what the most effective rep ranges are for you and how close to failure you should train to gain muscle. Without any further ado, let’s get into it.


Training Intensity: Rep Ranges

If we have to believe the old school bodybuilding magazines, you need to train with an 8-12 rep range. Even though this is a fine rep range for muscle growth, it’s not the only rep range that works. But before we dive into that, let’s look into where the 8-12 rep range stems from.

The Strength-Endurance Continuum

training intensity

The strength-endurance continuum is based on the “Specificity” principle we discussed in part 1 of this “Training Programming” blog series. If you train with low reps and heavy weights, you gain more strength. If you train with high reps and lower weight, your endurance improves more. This makes sense.

Since muscle growth is often seen as something that happens when your muscles can produce more force and handle more volume, the strength-endurance continuum also indicates that moderate rep ranges (e.g. 8-12 reps) work best for muscle growth.

But now that there is more research on rep ranges and muscle growth, it has become increasingly clear that muscle growth is not limited to a narrow rep range like 8-12. In fact, you can maximize muscle growth with a wide spectrum of rep ranges.

Rep Ranges & Muscle Growth Research

In a 2015 study, 18 volunteers were divided into 2 groups. Group 1 trained with the traditional 8-12 rep range to failure, whereas group 2 trained with 25-35 reps to failure (volume was equated by matching the number of sets). Both groups gained a similar amount of muscle after an 8-week training period.

In another study, researchers compared hypertrophy-type training (3 sets of 10 reps, 90 seconds rest between sets) with powerlifting-type training (7 sets of 3 reps, 3 minutes rest between sets) while matching training volume. In this study, volume was defined as Reps*Sets*Weight. Again, similar increases in muscle size were found.

Perhaps the most convincing piece of evidence is a 2017 meta-analysis that compiled the data of 21 training studies on rep ranges and muscle growth. The researchers found that muscle growth can occur with a wide variety of rep ranges, as long as volume is matched and the sets are taken close to failure.

So, there is no narrow “hypertrophy rep range.” How much volume you perform per muscle group and how close to failure you take each set is what matters.

Rep Range Recommendations

Now, just because there is no narrow rep range that mechanistically works best for muscle growth, does not mean you can just do whatever in your training and expect the best results. It’s also important to consider fatigue management and what is practical.

If you perform 20+ rep sets close to failure, every set will almost feel like a cardio workout. If you train with <6 reps on each set, every set will be very demanding and you will put quite a bit of stress on your joints.

For this reason, I still recommend my clients to train mostly in moderate rep ranges. I usually program within a 5-15 rep range. This allows you to accumulate volume efficiently. Also, this rep range is quite broad, so you can have repetition variation in your training. Training with both low- and high-rep ranges may be beneficial for muscle growth since this can help preferentially target both type I and type II muscle fibers. The research is still mixed on whether it’s actually possible to specifically target type I and type II fiber growth, but rep variation is still worth a try. If anything, your workouts feel less repetitive.

Training Intensity


Training Intensity: How Close To Failure?

Now that we’ve looked into rep ranges for muscle growth, let’s look into intensity of effort. You don’t have to train to complete failure to gain muscle. But you need to come close to failure.

The closer a repetition is to failure, the more effective that rep usually is for stimulating your muscles. As you come close to muscle fatigue, you recruit more muscle fibers and challenge your muscle’s present capacity more effectively.

There is research showing that beginner trainees tend to train pretty far away from failure. In one study, the participants sometimes left 6+ reps in reserve after each set when they self-selected their weights. This likely is too far from failure to produce meaningful results. So make sure you keep a close eye on whether or not your sets are actually challenging.

Keep 1-3 Reps In The Tank

Training intensity

Now, as mentioned, you don’t have to take each set to complete muscle failure either. Keeping 1-3 reps in reserve at the end of each set is a good aim. This ensures your sets are challenging without impairing your recovery.

Staying just a few reps shy of failure allows you to handle more volume and have better performance over time. A 2017 study shows this quite well. In this study, the participants that trained to failure had slower performance recovery compared to the group of participants that left a few reps in the tank after each set. Basically, you run the risk of not being able to perform optimally on your next training session(s) if you train to failure.

So, the reason I suggest you keep a few reps in the tank at the end of each set is not that I want to make things easier on you. We want to stay a few reps shy of failure so that you can maintain a high intensity in your next training sessions as well.



Main Points

  1. Muscle growth is not limited to a narrow rep range of 8-12 reps. You can gain muscle with a wide spectrum of rep ranges, as long as volume is matched and you train close to failure.
  2. To accumulate volume efficiently, it’s still a good idea to train in mostly moderate rep ranges. I suggest a rep range of 5-15 reps. This allows you to train in a variety of loading zones, which *may* help with targeting type I and type II muscle fibers.
  3. You don’t have to train to failure to gain muscle, but you need to train close to failure. Keeping 1-3 reps in the tank at the end of each set will usually ensure that your sets are challenging enough without impairing your recovery.


Final Words

I hope you enjoyed reading part 2 of this 3-part blog series on training program design! In a few weeks, I’ll post the third and final part. The last article will cover Training Frequency. Training frequency is mostly about how you organize the volume and intensity in your training. Do you do organize your training in a body part split? Full-body or maybe Upper/Lower? More on this soon!

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