Cluster Training for Strength and Hypertrophy

Introduction

I was recently asked on the Table Talk Crew Discord about how to include cluster sets within a training program. I initially gave a short answer before realizing the answer was much longer and more detailed than I initially thought.

Cluster training is an extremely effective and well-established training method. A method, like many
of the less “traditional” methods that doesn’t get utilized enough in people’s training programs. Clusters have a wider variety of applications. Most importantly, they are very effective as a tool to develop maximal strength, but not all they are good for.

Before we dive into the different ways cluster sets are used in your training, we must first define what they are.

A cluster set is a series of reps that are performed with a specific rest period in between. The exact number of reps and the rest periods will vary (as shown below). The principle stays the same. Cluster sets either allow us to achieve a higher volume of work at the same level of intensity/load or the same workload at a higher intensity/load.

The Benefits of Cluster Training

Cluster training is one of my favorite and most used strength methods. It comes with a whole host of benefits that include (but are not limited to):

High Volume at High Intensities

The rest periods between reps of a cluster set enable you to achieve more reps with the same percentage of your 1-rep max (1RM). This partial recovery can allow you to achieve up to double the number of reps per set. For example, most lifters can get three reps with 90% of their 1RM. Whereas in a cluster set, it is possible to achieve five or six reps. Also, performing a set of three at 90% 1RM is an all-out effort for many lifters—one which they can’t perform several times in a workout. Achieving two or three sets of five reps at 90% will be doable for most. It's easy to see how it allows you to accumulate a much greater volume of work with heavier loads

Higher Quality of Reps

The intra-set rest period allows you to evaluate your performance after each rep and make technical adjustments on the next rep. Not only that, but the partial recovery between reps will lead to a lower level of accumulated fatigue. Especially from a postural strength perspective (because you get to unload your body between reps), which in turn leads to more technically proficient reps.

Increased Practice of Set-up Procedure

Resetting between every rep of a cluster set gives you a chance to practice your set-up, walkout/un-rack, etc., more often than performing regular straight sets.

Improves Firing Rate

Once you have full fast-twitch fibre recruitment (usually around 80% 1RM), the only way you can produce more force is by increasing the firing/twitch rate of the fast twitch fibres. Accumulating more volume at these higher percentages of our 1RM allows you to spend more time improving their firing rate.

De-Sensitizing Golgi-Tendon Organs (GTOs)

The human body has built-in safety mechanisms that purposefully stop you from producing too much force—usually to prevent you from tearing a tendon off the bone or something like that. One of these mechanisms is the Golgi Tendon Organs, which sense how much force is being transferred through a tendon. At first, they are very sensitive and conservative, but exposure to near-maximal loads will desensitize them. By accumulating more volume at near-maximal loads, cluster sets allow us to desensitize these to a greater degree and/or more quickly.

Stimulates Hypertrophy

One downside of lifting heavy is that it can be difficult to accumulate enough volume to stimulate hypertrophy. As previously mentioned, clusters allow you to accumulate more volume at higher percentages of 1RM, making it easier for us to reach the threshold required to optimally stimulate hypertrophy. Since our loads will almost always be above 80% 1RM when using cluster sets, all of our reps will be maximally effective reps (MERs). Making it an incredibly efficient hypertrophy method that avoids non-effective reps.

The Downsides of Cluster Training

No training method is perfect. Cluster training may be a powerful stimulus, but that can
come with issues. So here are some things that you need to be aware of when programming cluster
training into your program:

Neurological Stress

Facilitating you to get more volume at higher percentages of 1RM is what makes cluster training so powerful. However, it is also capable of being its biggest downside. Too much volume performed at these higher percentages will be very neurologically demanding, so it’s important to dose the volume correctly and give yourself time to adapt to the increased stress.

Fast Rate of Adaptation

As always, the stronger the stimulus a method provides, the faster the adaptive response. So, it is not realistic to use cluster sets constantly, as you will quickly reach a point of diminishing returns. You can potentially use them for up to 10-12 weeks if you periodize them well with a progression system where you use progressively more intense cluster variations. But in most scenarios, you would use them for 4-6 weeks as this is enough time to get the benefits of this style of training with minimal risk of “burning out.”

Requires the Use of Heavy Loads

Most of the benefits of cluster training are only present when using heavier training loads, generally 85% 1RM or higher. So, clusters are not a great option if you are at a stage of your training where you are trying to limit heavier loading or if you struggle to recover from heavier loading.

Joint/Soft Tissue Stress

Another downside of a higher volume of heavier lifting is the increased stress on your joints, connective tissue, tendons, etc. This is why it is important to remember that clusters are generally not recommended for beginner lifters and are best used with movements that you are technically proficient with so that you can limit the possibility of any additional stress due to poor technique or unfamiliar loading patterns.

Types of Cluster Sets

There are many different types of cluster sets that you can use in your training. While they share
many common traits, we can adjust the loading, number of reps, rest periods, and other factors to
help bias the cluster set towards a specific goal. Below I will outline the types of cluster sets that I use most and some general guidelines for how to program them. Notice the differences between each Cluster type and how those differences can change the outcome.

Poliquin Clusters

Charles Poliquin is accredited with popularising cluster sets. Poliquin’s recommendations for cluster sets work well for those after a mix of strength and hypertrophy due to the lower loading zone and higher number of reps. Likewise, this works best with intermediate lifters due to the shorter rest periods. Fifteen to twenty seconds of rest can work well for those who are not close to their “true” ceiling strength-wise and also have a very good aerobic fitness base (i.e., many sports athletes). But with advanced or very strong athletes, this simply won’t be enough of a rest period to recover, meaning they would either have to lower the load used significantly (not ideal) or wouldn’t accumulate enough reps.

Programming Poliquin Clusters

Number of reps in a set: 5
Rest between reps: 15-20 seconds
Load: 87-90%, or your 3RM
Number of sets: 3-5

Miller Clusters

Carl Miller is likely the person who invented the methodology of clusters. He originally developed them for use with the Olympic lifts and their variations (as he was a very high-level Olympic lifting coach) but these guidelines work just as well for the traditional strength lifts. In reality, you can use slightly more load with the traditional strength lifts due to them being less technical, which I have taken into account with my recommendations below. These were developed in the context of coaching high-level Olympic lifters, so as you’d expect, these tend to work better with stronger and more advanced athletes. The longer rest periods allow enough time for the athlete to recover from the increased stress of each rep. Carl generally used two different styles of cluster sets:

Extensive clusters: More appropriate for accumulation or early intensification phases.

Intensive clusters: Better suited for later intensification or realization phases.

Programming Miller Extensive Clusters

Number of reps in a set: 5-7
Rest between reps: 30-45 seconds
Load: 85-92% for strength movements, 80-85% for the Olympic lifts

Number of sets: 3-5

Programming Miller Intensive Clusters

Number of reps in a set: 2-3
Rest between reps: 45-60 seconds
Load: 87-95% for all movements (clean & jerk could be as low as 82%)
Number of sets: 3-4

Mentzer Clusters

Mike Mentzer is known for his style of low-volume, very high-intensity training. Even though Mentzer was a bodybuilder, he was incredibly strong and it is methods such as the Mentzer cluster that he attributes a lot of that strength to. This is a very advanced and intense method that is only recommended for very advanced athletes. Even then, I would still recommend extending the rest periods to more like 40-60s to allow adequate recovery, otherwise, most athletes won’t be capable of completing the set. The first three cluster reps are performed at 95% of your 1RM, then you reduce the load to 85% 1RM and aim to get another two or three cluster reps. As I said, this is for advanced trainees with very good technique. Since the average intensity is so high, you would need to perform less volume when using this variation.

Programming Mentzer Clusters

Number of reps in a set: 5-6
Rest between reps: 15-20 seconds (although I would program using 40-60s)
Load: 95% then 85%
Number of sets: 1 or 2

Drop Clusters

With drop clusters, you reduce the load from rep to rep to account for the partial fatigue you will accumulate. This allows you to start with a heavier load on the bar at the start of the set and achieve a higher average intensity throughout the set. Let’s say you do a regular cluster set of 4 reps with 90% of your 1RM on the bar. The first rep is reasonably submaximal; after all, 90% is something most lifters can hit for three reps. But if you accumulate 2% fatigue from rep to rep (due to the incomplete recovery between reps), that 90% becomes progressively more difficult. So, it would look like this:

Accumulated Fatigue vs Relative Intensity

Rep Number	Bar Load	Accumulated fatigue	Relative Intensity*
1	90% 1RM	0%	90% 1RM
2	90% 1RM	2%	92% 1RM
3	90% 1RM	4%	94% 1RM
4	90% 1RM	6%	96% 1RM

Even though the load stays the same, the relative intensity increases from rep to rep. By the time you have performed four cluster reps, the load on the bar now represents 96% of our maximum AT THAT MOMENT. Across the set, this gives you an average intensity of 93%. When you perform a drop cluster, you reduce the load from rep to rep, which allows you to start with a heavier load and achieve a higher relative intensity for the set, which has obvious benefits for maximal strength development. A drop cluster would look something like this:

Rep Number	Bar Load	Accumulated fatigue	Relative Intensity*
1	96% 1RM	0%	96% 1RM
2	93% 1RM	2%	95% 1RM
3	90% 1RM	4%	94% 1RM
4	87% 1RM	6%	93% 1RM

Here, your average bar load is 92% 1RM and your average relative intensity is 95% compared to 90% 1RM and 93% from your previous example. This may not sound like much, but when you're training for maximal strength and the volume you can handle is low, having your average relative intensity 2% higher is significant.

Overload Clusters

Overload clusters involve weight releasers or eccentric hooks to add extra load to the eccentric portion of the lift. When using these devices, you have no choice but to perform cluster sets since you have to reset them on every rep (unless you use them as an activation tool on the first rep only, which is a different strategy altogether). Overloaded eccentrics and weight-releasers are one of my favorite methods for improving maximal strength in a short time.

The only “downside” to them is that because the stimulus they provide is so strong, you can use them only for one training block (or two short blocks if you change methods) before you’ve milked everything out of them. I speak extensively about these and other eccentric methods in our second Table Talk episode, so I don’t want to go into too much detail here. But I have put the link to that episode below so that you can find out more information should you wish:

Programming Cluster Sets

When programming cluster sets using these devices, I would follow these guidelines:

1. Program Using Average Load (Eccentric/Concentric)

When determining load using overloaded eccentrics/weight releasers, use the average load of the eccentric and concentric. Generally, you don't want the bar/concentric load to be above 80% as otherwise, the concentric can get a bit too “grindy” after the increased fatigue of the overloaded eccentric. So, use 80% bar weight (for the concentric) and then add a further 20% via the releasers (10% on each) to give us 100% 1RM. This would give us an average load of 90% 1RM. So, when programming clusters using this method, you would treat the reps as if they were being done at 90% 1RM.

2. Don’t Go Above 110% 1RM on the Eccentric

Yes, there are some benefits to having an eccentric strength of 120%+ 1RM but there is a case of diminishing returns here and, for the vast majority of lifters (not sports athletes), the extra fatigue and injury risk of pushing towards 120% is simply not worth it.

3. Increased Neurological Demand

As mentioned, weight-releasers provide a strong stimulus, especially to the nervous system. This is a double-edged sword because it means you can make rapid gains in strength through improved neurological factors, but we also must dose the volume very carefully so you don’t overstress the nervous system.

4. Reduce Volume

A 10-20% reduction in volume when using weight releasers will generally be enough to avoid any excessive neurological fatigue while still achieving enough workload to stimulate the results we want.

Programming Overload Clusters

Number of reps in a set: 3-6 (depending on the loading scheme being used)
Rest between reps: 50-60s
Load: Generally 80% on the concentric and 100-110% on the eccentric, but this will vary
Number of sets: 2-3

Technical Clusters

Technical clusters are slightly different from the other cluster methods I have addressed so far. As the name suggests, this method aims to improve technical proficiency with heavy but submaximal loads. The loading generally will not be heavy enough to maximize the neurological adaptations I discussed earlier, such as improving the firing rate.

Will you get some of those adaptations? Yes. Will they be gained at the same rate or to the same level as some of the more “intense” methods discussed previously? No. What these clusters do achieve, however, is providing plenty of chances to improve your technical efficiency with loads that are heavy enough to have the improvements translate to maximal loads. This includes the parts of the lift that are often neglected, including the set-up, un-rack, walk-out, and so on. Yes, you could do your technical practice with lighter loads, but I find this method less effective for a few reasons:

1. Hypertrophy

Technical clusters are heavy enough that all the reps performed are maximally effective reps and can contribute to hypertrophy (which would not be the case with doing say 8 x 2 @ 60% 1RM). This may not be the main aim here, but more hypertrophy certainly isn’t going to hurt your performance.

2. Muscle Fibre Recruitment

Muscle fibre recruitment patterns are different with heavier loads compared to lighter loads due to the speed of movement. If you look at the recruitment pattern of an explosive or plyometric movement, it is different from that of a heavier rep performed on that same movement. So, to a degree (but certainly not entirely), the recruitment pattern is velocity or load-dependent. Performing technical clusters at 80%+ 1RM gives you the same recruitment pattern that you would see with a maximal attempt, which makes it easier to translate any alterations you make to those heavier lifts.

3. Technique Work

Heavier loading can make it easier to address technical issues and weaknesses. Lighter technique work is often performed with such a fast movement/bar speed that it can be difficult to notice any deviation that needs correcting. Not only that, but lighter loads will often not be heavy enough to cause any weak points to rise to the surface. Just about anyone can lift 60% 1RM with perfect technique, but what happens when that same lifter is using 80, 85 or 90% 1RM? It can be a very different story. Am I saying lighter technique work is useless? No, of course not. But if we are looking for a way to do technical work with an intermediate/advanced lifter with a more direct carryover to their heavier work, then I believe technical clusters are a more efficient way of achieving that.

Programming Technical Clusters

Number of reps in a set: 4-6

Rest between reps: 40-60seconds

Load: 80-85% 1RM

Number of sets: 2-4

Hypertrophy Clusters

Last but certainly not least, I come to hypertrophy clusters. Once again, the name tells you straight away that these clusters have a slightly different end goal from the earlier methods I touched on. Cluster training is biased more towards hypertrophy with a few simple tweaks. As I mentioned in the introduction, one of the great things about cluster training is that in the vast majority of cases, all the reps performed will be maximally effective reps (MERs) due to the load being 80% 1RM or above. This means you can accumulate a high number of MERs with a low total volume of work, making it a very efficient hypertrophy stimulus.

The only downside is that it can be difficult to accumulate enough total volume per session if using a more traditional cluster approach as you will become very neurologically fatigued before you have completed the desired workload. Then, there is the fact that cluster training is time-consuming.

Enter Hypertrophy Clusters

These are performed using slightly lighter loads, 75-80% 1RM, which allows you to perform multiple reps per “micro set” without accumulating too much fatigue. By performing 2-3 reps per “micro-set,” you can achieve as many as 10-15 reps per cluster set. Not only that, but you achieve that greater volume in less time compared to a regular cluster set because you spend less time resting between reps, setting up, un-racking, and so on. This increased time efficiency, along with the lighter loading, helps navigate both of the downsides I mentioned above. These can be performed on several movements within a workout, say if you are training using a whole-body, upper/lower or push/pull split and need to hit several movement patterns.

Alternatively, they can be used for your “main lift” at the beginning of your hypertrophy session before performing the rest of your movements using more “traditional” hypertrophy methods. Another benefit of including this method in your hypertrophy training is that it allows you to continue improving neurological factors while focusing primarily on hypertrophy. This aids long-term hypertrophy goals as they will facilitate an improved level of performance and more load being used on our movements, leading to a greater stimulus over time.

Programming Hypertrophy Clusters

Number of reps in a set: 10-15
Reps per “micro-set” – 2-3
Rest between “micro-sets” in a cluster: 40-60seconds
Load: 75-80% 1RM
Number of sets: 2-3

Conclusion

As you can see, cluster training has a wide variety of applications within a training program, depending on which “style” of cluster you choose to use. The above is by no means an exhaustive list. If you wanted to, you could come up with plenty of other variations depending on what goal you are trying to achieve. Chances are that you could benefit from including cluster training in your programming from time to time.

There’s a reason that cluster training is one of my favourite training methods. It rarely fails to deliver impressive results. But just like any training method that delivers a powerful stimulus, it is easy to “burn out” if you abuse the method by overdoing the volume or using it for too long. So, just be wary that the results from this style of training can be a little addictive…

---

Tom Sheppard is a UK-based strength and powerlifting coach. As a coach, he has worked with professional athletes from a wide variety of sports worldwide, including rugby, baseball, MMA, and high-level powerlifters. Tom is the co-owner of Phoenix Performance and the Head Coach at Thibarmy. He also contributes content for companies such as elitefts and T-Nation. Tom presented at the 2023 and 2022 SWIS Symposium alongside some of the biggest names in the fitness industry.