What is a Cluster Set? A Complete Guide

Written by Adam Tzur and Brandon Roberts | Published: October 10, 2022

What is a Cluster Set?

In strength training, cluster sets are small sets inside a regular set. These small sets are known as sub-sets. Short rests are added between every sub-set. This allows your muscles to recover, and you can train with heavier weights with less fatigue.

How to do a cluster set: 

1. Divide your regular set into 2-4 sub-sets.
2. Do 3-5 reps per sub-set. [6]
3. Rest 15-45s between every sub-set. [3] 
4. When done with the sub-sets, take a normal rest (2-4 minutes).

For example: Instead of doing 12 straight reps, you now do 4+4+4 reps, with rest between each sub-set. We call these intra-set rests, meaning rests within the set. inter-set rests are rests between sets.

Do few reps with heavy weights

Strength scientists recommend doing 3-5 reps per sub-set. [6] You should take short rests within the set and avoid going to failure. 

This technique allows you to maintain good form, even with heavy weights. And you can lift more total volume without the exertion and fatigue of straight sets. If your bench press 3 rep max is 140 kg, then it might be 5 rep max inside a cluster set.

That is why professional weightlifters have used cluster sets since the 1950s. [1]

Example of a Cluster Set

This figure illustrates what a cluster set looks like, and how it compares to a regular set.

Here’s how to do it:

Cluster set

• Sub-set 1: Do 4 reps
• Rest: 20 seconds intra-set rest
• Sub-set 2: Do 4 reps

Rest

Rest for 3 minutes, then do the next set.

Regular set

• Do 8 reps in a row

Rest

• Rest for 3 minutes, then do the next set.

Note that in the example above, you do the exact same reps. There is no rule for how many reps or clusters there should be in a cluster set.

Differences between cluster sets and straight sets

• Cluster sets use rests within the set (intra-set rest)
• Cluster sets allow for better lifting form
• Cluster sets are less fatiguing

Because of these differences, you need to do more total reps or use higher weights with cluster sets. If you don’t, you simply end up adding more rest to your regular sets.

Are Cluster Sets Effective at Building Strength and Muscle?

Studies say yes, cluster sets are good for building both strength and muscle mass. 

But clusters aren’t better than straight sets for this purpose.

Scientific data: 18.6% increased strength

In 2021, Davies and colleagues analyzed all cluster set studies on strength and hypertrophy.

They found that the participants who trained with cluster sets increased their strength by 18.6%, on average. Participants who trained with traditional sets gained 18.4% strength. The median study duration was 7 weeks. [1]

You can use this data as a rough estimation to what you can expect in terms of gains.

Cluster sets and regular sets lead to similar strength gains.

Scientific data: 2.7% increased muscle mass

Davies also found that the participants who trained with cluster sets increased their muscle mass by 2.7%. 

In comparison, participants who trained with traditional sets gained 4.8% muscle. [1]

So is traditional training better than cluster training for muscle hypertrophy?

Not quite. According to the data:

• The differences were not statistically meaningful
• Most of the hypertrophy studies had participants who were new to strength training 
• Data in untrained beginners may not apply to those who have trained longer

Cluster sets and regular sets lead to similar muscle gains. Regular sets might have a slight edge.

Benefits of Cluster Sets

Less fatigue and exertion

In a regular set, you become more and more fatigued with every rep. If you lift until you can’t do any more reps, you have reached muscle failure.

Cluster sets help you keep fatigue low, and they reduce perceived exertion [1] [3] [5]. 

Better form and technique

When fatigued, your weak points become exposed and they affect your technique. We’ve all had it happen to us: we start to use momentum and cheat as we become tired. 

The problem grows if you make bad form a habit. Remember that with every rep, you are reinforcing a movement pattern: your own technique. Low quality reps with poor form may lead to slow gains or even injuries.

Cluster sets are a great tool for practicing technique, because they prevent form breakdown. This could allow you to train with more volume and high quality reps during a workout [5].

Cluster training can be especially useful if you start to grind during your set. Grinding is when your lifting speed slows down to a crawl, because you’re getting close to muscle failure. 

For example, you’re doing barbell bench presses for 8 reps: Reps 1-6 go fine, but you have to grind through reps 7 and 8.

A way to overcome this issue is to do cluster sets of 4+4 reps. You break your regular set in two, and add a rest in-between. 

Alternatively, you could do 4+4+2. Now you’re doing three sub-sets with two more total reps, and your form is good because of the extra rests.

You don’t have to do it for every set of every exercise, but try it out if you have a specific challenge to fix.

In my experience, this way of training overcomes grinding and stubborn sticking points.

Higher volume 

One of the biggest benefits of cluster sets is you can lift more weight for more reps with less fatigue. This means that it’s a good tool for increasing training volume. [4] [5] [6]

Personally, I use them as a quick way to add more reps and volume to the last set of an exercise. 

Let’s say I’m doing 3 sets of 10 reps for the deadlift. By making the last set a cluster set, I can do 2 sets of 10, and then 1 cluster set of 6+6 reps. 

Increased power

Power is the ability to produce force rapidly. 

This is the formula: Power (P) = Force (F) * Velocity (v)

For example, when you are jumping: if you do the movement slowly, you won’t get off the ground. You must do the movement quickly and forcefully.

We can apply the same logic to olympic lifts: the power clean, the clean and jerk, and the snatch. 

All of these lifts are dependent on producing power and creating momentum to clear the lift.

Here is how cluster sets affect power:

• Traditional sets lead to reps with lower velocity as you reach the end of the set [4]
• Lower velocity = less power
• Cluster sets maintain power and velocity because fatigue is low [3] [4] [5]

Drawbacks of Cluster Sets

Time consuming

Clusters can be time consuming, depending on how you program them. More rest means more time in the gym.

More complex workouts

Not only will you have to keep track of all your exercises, sets, and reps. Now you need to track the clusters, as well. More complexity isn’t always a good thing. Sometimes it’s nice to keep the workouts short and simple. 

Not superior for building strength or muscle

As we covered above, cluster sets can lead to good gains in strength and muscle mass. They aren’t superior to regular sets, however. This means they have specific uses. 

The main uses would be practicing form, adding fatigue free volume, and building explosive power.

How to Plan a Cluster Workout

Step 1: Choose your cluster exercises

We recommend that you stick to barbell exercises for cluster sets. Compound exercises such as the bench press, deadlift and squat are well-suited. 

There is no need to use clusters on isolation exercises, like leg curls. 

The reasons are simple: 

• You rarely need to work on your form or explosive power for the leg curl. 
• You are most likely doing curls to build muscle, and cluster sets are not better than regular sets for hypertrophy.

But there is one exception: unilateral exercises. The benefit here is you can rest one limb while training the other. 

A normal unilateral exercise set might look like this (biceps curl):

1. Do one set for the left arm
2. Do one set for the right arm
3. Rest 2 minutes

With a unilateral cluster set, it could look like this:

1. Do the first sub-set for the left arm
2. Rest the left arm while doing the first sub-set for the right arm 
3. Rest right arm while doing the second left arm sub-set
4. Rest left arm while doing the second right arm sub-set
5. Rest 2-3 minutes

Step 2: Pick the weight, sets, reps and rests

Weight	Sub-sets per cluster set	Reps per sub-set	Rest between sub-sets	Rest between cluster sets
70-90% of  1 rep max (RM)	2-4	3-5	15-45 seconds	2-4 minutes

 

When programming cluster sets, it’s a good idea to add more volume or intensity. 

If you just take your old sets and splice them in half with a rest, your muscles may be understimulated. 

The rest time between sub-clusters should be 15-45s [3]. Use 10-20s for isolation movements, and more than 15s for compound movements. [6]

In terms of reps, aim for 3-5 reps per sub cluster set [6]. The total amount of reps depends on how many subsets you do.

The simplest way to create an effective cluster set is to divide a regular set into two sub-sets and add 2-4 more total reps.

Step 3: Add it to your program

The key to cluster sets is to be intentional. You need to decide which exercise you want to improve on. 

Does your squat need more power to clear the sticking point you have at the bottom? Or does your bench press need more training volume with less fatigue?

The easiest way to do it is to turn the last set of an exercise into a cluster set. 

This strength training technique lends itself to creativity. Experiment and figure out how to use it in your program.

A cluster workout for the upper body

Tip: Have a spotter

Practically speaking, some exercises can trap you under their weight. The bench press is a classic example. 

When you’re using cluster sets, you’re going to be re-racking weights a lot. If you’re alone, you will spend energy needlessly racking the weight between the intra-set rests. Racking weights can itself be fatiguing.

A spotter has the dual benefit of keeping you safe as you rack the weight, and they can help prevent racking fatigue. 

You shouldn’t need a spotter for machine exercises or isolation exercises. But barbell exercises like the bench press are riskier. 

This is especially true when you’re just getting used to cluster sets. You may not know when you’re about to reach muscle failure. 

Strategies for Advanced Lifters

This section is for powerlifters, olympic weightlifters, strongmen, and coaches.

Clear the sticking point

The sticking point is the weakest link in your range of motion for a given lift. It is where you stop and grind. Your form breaks down and you risk injury. [2]

Notably, force development and velocity is impaired during and after the sticking point. [2]

If you could fix the sticking point, you could improve your lifting performance.

And as we discussed earlier, force and velocity create power. Cluster sets are a good way to not only maintain power as the set goes on, but they can also increase power. [3] [4] [5]

Which makes it a powerful technique for improving lifts that you have to grind through. 

Break plateaus

In a linear progression, you increase the load while maintaining the same number of reps. 

Week 1: 100 kg x 10 reps, week 2: 102,5 kg x 10 reps, and so on.

This gets harder once you become an intermediate lifter.

Cluster sets can be a way to keep progressing into new PRs.

Let’s say you are stuck at 210 kg x 5 reps for a given exercise. Every time you increase the weight beyond 210 kg, you can only do 4 reps.

With a cluster set, you could try 212,5 kg x 4+2 reps. Do this for some weeks, and try to increase the number of reps in the second sub-set (4+2 to 4+3 to 4+4). If it’s too hard, try to change the intra-set rest.

Now see if you suddenly can’t do 212,5 kg x 5 reps in a regular set.

Ascending cluster sets

With normal cluster sets, you’re using the same weight for every sub-set. Ascending cluster sets are an intensity technique where you increase the load for every sub-set. In the example below we increase the weight while decreasing reps. 

These sets can be an advanced technique to try out if your progress stalls.

1RM = 200 kg	Sub-set 1	Sub-set 2	Sub-set 3
Reps	4 reps	3 reps	2 reps
Weight	170 kg (6RM)	180 kg (4RM)	185 kg (3RM)

 

References

1. Davies TB, Tran DL, Hogan CM, Haff GG, Latella C. Chronic Effects of Altering Resistance Training Set Configurations Using Cluster Sets: A Systematic Review and Meta-Analysis. Sports Medicine (Auckland, N.Z.). 2021 Apr;51(4):707-736. DOI: 10.1007/s40279-020-01408-3. PMID: 33475986.
2. Kompf J, Arandjelović O. Understanding and Overcoming the Sticking Point in Resistance Exercise. Sports Med. 2016 Jun;46(6):751-62. doi: 10.1007/s40279-015-0460-2. PMID: 26758462; PMCID: PMC4887540.
3. Latella C, Teo WP, Drinkwater EJ, Kendall K, Haff GG. The Acute Neuromuscular Responses to Cluster Set Resistance Training: A Systematic Review and Meta-Analysis. Sports Medicine (Auckland, N.Z.). 2019 Dec;49(12):1861-1877. DOI: 10.1007/s40279-019-01172-z. PMID: 31506904; PMCID: PMC6851217.
4. Marshall J, Bishop C, Turner A, Haff GG. Optimal Training Sequences to Develop Lower Body Force, Velocity, Power, and Jump Height: A Systematic Review with Meta-Analysis. Sports Medicine (Auckland, N.Z.). 2021 Jun;51(6):1245-1271. DOI: 10.1007/s40279-021-01430-z. PMID: 33666895.
5. Tufano JJ, Brown LE, Haff GG. Theoretical and Practical Aspects of Different Cluster Set Structures: A Systematic Review. Journal of Strength and Conditioning Research. 2017 Mar;31(3):848-867. DOI: 10.1519/jsc.0000000000001581. PMID: 27465625.
6. Vargas-Molina S, Petro JL, Bonilla DA, Baz-Valle E, Carbone L, Cannataro R, Benítez-Porres J. Cluster Sets for Muscle Hypertrophy: A Short Review. OBM Integrative and Complementary Medicine 2022; 7(1): 010; doi:10.21926/obm.icm.2201010.