By Carl Valle
Dr. Oliver’s presentation on cluster sets from the NSCA Conference was so compelling I had to experiment right away with that modality. I have touched on cluster sets just lightly, because potentiation and contrast training competed in popularity over the last few years. When faced with several options, sometimes a good idea or valuable method can fall on deaf ears, so I decided to make cluster training a priority for two seasons before writing anything definitive.
Based on my experience, if you are not dabbling with cluster sets, you are leaving so many benefits on the table it’s borderline foolish. The science and practice both support the use of cluster sets, so I recommend trying them out with your athletes or your own training.
Why Another Article on Cluster Training?
I didn’t originally want to write this article, as enough bodybuilding or weight-training articles go over the topic, and I felt I addressed cluster sets enough previously to get people thinking about it. After talking to a few coaches, it seems most view cluster sets as something nice to have—nobody got excited about it like potentiation, complex, or contrast training. Clusters were accepted but not loved, but after spending a few years working with cluster-style training, I am a believer. After a few months, cluster sets seemed more of a burden than a benefit, but after two seasons I will admit I they were more potent than I thought.
The truth of cluster sets is that they require more work, literally, in the training and planning than conventional straight sets. So, is it worth implementing within a program? If you have athletes that are hitting plateaus or have weight requirements, cluster training might be the best medicine. I have had a few athletes that simply ran out of improvement space in the weight room, as their off-seasons became shorter from playoff runs and they were simply getting older. After using some of the research directly in our training, my skepticism was met with evidence and I knew I I should share my results.Cluster sets require more work—literally—in training and planning than conventional straight sets. Click To Tweet
Overall, everyone I assigned to cluster repetitions in the last two years got better, but only if they were matching previous strength levels. My feeling with advanced techniques is that they often mask poor lifestyle decisions, and coaches see them as shortcuts to getting better without putting in the necessary effort, dedication, and sacrifice.
Cluster sets are no longer options in my training; they are the new standard that everyone uses to get better. Countless articles, research studies, online workouts, and gurus tout the method, and I join them. I go on record saying that cluster training is a must.
Cluster Training: Is it Just Rest Between Sets and Reps?
Cluster sets are more straightforward than complex, contrast, and potentiation, as they are simply about rest patterns. Output can be maintained by adding rest between reps, as fatigue will rise during straight serial bouts, such as conventional lifting or jumping. In track, some coaches do split runs to keep the total output faster or higher in quality, but clusters basically inject a little more rest at the right locations to improve power expression.
Scientifically, rest can be inter-repetition, inter-set, or intra-set in nature. Manipulating rest by adding seconds between reps or adding a minute or two between sets may keep athletes sustaining velocity and power. Straight sets deplete the neuromuscular system and provide an advantage with hypertrophy and possibly strength, but if you want to push the envelope, clusters seem to be superior based on the research. This article will start to get confusing, so I will provide a working definition for each rest period.
- Inter-Set Rest: The passive rest time period between sets
- Intra-Set Rest: The passive rest time period clusters of reps within a set
- Inter-Repetition Rest: The passive rest time period between each repetition
Note that I added the term “passive” to Dr. Oliver’s presentation to ensure people don’t see clusters as rest-pause training or drop sets. When you do cluster reps, you walk away and either rack the weight or drop the weight. Cluster repetitions are for maximal exertion work, not for assistance exercises. When you manipulate the rest period by adding more time, you get nearly the opposite response than density training.Rest is often seen as something you do when needed. Plan it to enhance the training effect. Click To Tweet
Density training decreases rest, and cluster training can be a wonderful juxtaposition for athletes needing dramatic changes from compressed style sessions. It’s easy to think that cluster training is just splitting hairs—in this case, splitting reps—but rest matters. The most underrated variable is rest, and it’s often seen as something that you do when needed, instead of planned to enhance the training effect.
What Are the Scientific Benefits of Cluster-Style Training?
So why cluster repetitions? In the past I would have just answered that power stays higher during the training session, but according to Dr. Oliver, cluster-style training does nine things better than traditional straight sets, or sets that have reps continuously strung together:
- Greater total power output during bench press training
- Greater force, velocity, and vertical displacement during Olympic lifts
- Greater power output during ballistic jump squats
- Better maintenance of technique throughout the unit of training
- Better maintenance of jump height and distance
- Lower ratings of perceived exertion after training
- Lower reliance on glycolytic pathways during training
- Similar increases of muscular strength after a training cycle
- Similar androgen and hormone responses to training
So, anything else? Well, another benefit I like is that cluster sets increase what Scott Damman calls “barbell discipline.” Cluster training is by nature less social because the racks can’t be flooded by four athletes; clusters are usually about pairing up with a good partner and doing work. I fault myself for not doing more cluster work earlier because I see too much “night club” attitudes coming from athletes today. Either an athlete has been grinded down so much they are burned out of the weight room, or coaches have been so buddy-buddy that training was loose and didn’t keep athletes in check.
All of the benefits are real, meaning you know after investing time into clusters that they are giving back, but only after a few months of programming them in twice a week. In a training calendar, only after a heavy or serious off-season will you see the physiological benefits, but after only one session you see athletes hunkering down. Clusters allow me to coach and not be a disciplinarian, and when using velocity feedback with barbell measurement tools everyone is engaged. Cluster training is a win-win for both the athlete and coach.
Anatomy of Design With Cluster Reps
The application of cluster reps isn’t something you just tweak on your training template to add spice or variation; it’s something you need to invest a little time and thought into. Clusters are not options; they are selected solution to help coaches deliver more juice to each rep. Programming a session requires knowing how many athletes are training in tandem and how the rest periods will solve problems or create bottlenecks in workflow. Cluster sets are selfish workouts, meaning each athlete will require a lot of time to think about what will work for them best. Also, cluster training doesn’t have a lot of formal rules, but here are a few guidelines.
Use cluster training for main sets, lower body work, and benching; for athletes who don’t need hypertrophy; and only for advanced athletes that require it. Athletes must think about only the cluster they are doing, and not think ahead. Coaches can advance the weight with cluster sets, but I would rather just do singles with conventional straight sets. Clusters is about distributing high power output through the training, not as a way to work on maximal strength. Athletes and coaches can get similar strength benefits as stated earlier, but it’s really a power solution for coaches.
Generally, coaches should add more rest and decrease rep clusters (amount of reps per cluster) as an athlete advances. It is unnecessary to start off with high rest and low reps early, and a good idea is to ride the option as long as possible by slowly tweaking the variables. I tend to double the rest between clusters and take off a rep each phase or even each year. Inter-set rest tends to lengthen last and I don’t like resting too long while lifting, as the athlete can feel the momentum wane.Clusters reveal what an athlete can do vs. pushing them beyond what they should do. Click To Tweet
Clusters are not rocket science, they just need to be done with good supervision and let the rest do the motivation. Save the cheering and the screaming for the games, as rest is the ultimate motivator and arousal. When an athlete can feel the difference in freshness, the beast will reveal itself inside the athlete. I love clusters because they reveal what an athlete can do versus pushing an athlete beyond what they should do.
Planning and Periodization Considerations
Several factors come into play when planning workouts with athletes, and to me it’s knowing how to take the benefits as proposed by Oliver and look for opportunities to insert clusters when it’s appropriate. I prefer to do clusters during the competitive phase of the season or during times of deep off-season work. The reason I prefer not to do clusters during the pre-season is that most of the time the merging of scrimmaging or practices with the team sport head coach doesn’t jive. Speed athletes in Olympic sport are a different story, and I use cluster training during the Specific Preparation Phase or SPP. Those are not my preferences per se, they are just my experiences. It’s going to be up to everyone else to share their results so I can experiment more.
I have tried clusters instinctively in tapering athletes in the past, and they felt fresh and sharp at the end of the season. The reason I twice tried clusters later in the season was because I wanted the athlete to be psychologically ready and sometimes they need to be distracted. Other times we just did maintenance work so we could make easy decreases in volume without complicating things, but knowing when to use something, or better yet when not to do something, is very individualized. I don’t do cluster reps with ballistic jump squats because I like rebound work as it allows rhythm to help athletes execute better, but in general the quality of movement is higher when reps are bite-sized.
Finally, If I have an ectomorph or an athlete that needs more mass, I stay away from clusters for most of the preparation phase. Time-under-tension, regardless of load, works for increasing cross-sectional growth of athletes needing to put on mass. I tried to get too smart one season with an offensive lineman who wanted to put on 10 kilos, and did too much power work. While the diet and low amount of conditioning enabled him to gain the muscle, I still felt that we could have done much better and I was convinced when we switched the program the following year.
New Ideas and New Technology to Amplify Rest
Not much has changed since the advent of clusters, but what has helped is the use of leaderboards and velocity-based training technology. Clusters are best utilized when training for power and speed, as percentages are estimates and dialing in exact outputs is far better than guessing and adjusting later. Manipulating rest has a cause and effect, and the use of bar speed tools helps with feedback for cluster training, as well as for traditional sets. As athletes get more experienced, they will finish straight sets with confidence and keep cluster reps nice and hot.
In Dr. Oliver’s research, cluster training was measured with less-conventional metrics, such as barbell stroke and athlete technique. In the past, cluster sets were always about getting more work done; now they’re a combination of quality work with both output and form. I have fallen in love with cluster sets more and more because of the new science and the new technology. It’s a perfect fit.
Leaderboards are great ways to help with cluster workouts, since the athletes are often spread out more and this allows a team to see who is doing what during the inter-set rest periods. Due to the decreasing cost of flat screens, new facilities are using small tablets and investing in more large-size flat screens for biofeedback. The issue with audio feedback is that it’s hard to know who the alert is for, and this is the reason a human still is part of the game—a strong voice is a timeless way to support training.
Example Training Sessions With Cluster Sets
I will share three workouts I am finding success with, and they are mainly vanilla with a little “special sauce.” I don’t have any special names for the workouts as mentioning clusters is enough to evoke some sort of buy-in with most athletes. Clusters are common enough that they may have heard of them, but they are not common enough that they are not useful to implement.
Clusters can be paired (contrasted and complexed) with other exercises, so the key is to monitor output and not get too fancy. Always remember how much power and speed athletes demonstrate versus good traditional work as a comparison, and still try to exhaust the system by doing enough volume and intensity so athletes feel it the next day but not during it.
Standard Cluster Triples for Squats
Using a squat rack, have the athletes perform six reps with 30-90 seconds between clusters and two to three minutes between sets. Three to four total work sets help a less-experienced athlete keep the quality up during the season without taxing them with loads. Using triples is a great way to transition to higher loads later without grinding reps. While each rep doesn’t have rest, the key is making sure the second set of three has high output without residual fatigue the next day. We are still experimenting with this protocol, but what we know is it’s great for keeping athletes fresh without decreasing total work. Ideally others will evolve this so it’s even more useful for athletes.
Video 1: While clusters may create more time racking the weights, it’s a good idea to use them when you want to regulate stress with more precision. Athletes who are sensitive to DOMS love clusters because they feel the reps are sharp and crisp.
I have mentioned in the past in articles on VBT that very slow reps sometimes fatigue more than they stimulate; meaning the residual soreness and fatigue is not worth the adaptation that other options can provide. Doing triples with a small break can get a lot of work done in the primary lift in just about 20 minutes or so. Usually you can do one or two warm-up sets after practice or use the first set of clusters as a transition. As the load increases, it’s important to make sure athletes don’t jump too much, so use a few warm-up sets and cut out one to two main sets if needed. It’s better to get 12 awesome reps than 24 causal reps.
Clean Pulls Singles for Power
Clean pulls are not my favorite, but I will use them when an athlete has true orthopedic restrictions or limitations from bad genetics with their flexibility. In addition to clean pulls, I do use lift-off work with cleans to teach postures, but we are careful to always include eccentric hamstring exercises after as the movement is mainly concentric. Due to the nature of clean pulls having no catch, this is why using a Gymaware or device that displays barbell displacement is a godsend. As the load gets heavier, many skilled and unskilled athletes change their technique and distance readings along with power keep everyone honest.
Video 2: Sometimes an athlete who has problems catching orthopedically or technically can benefit from clean pulls. The catch is a great option for bracing, but due to the low drop the eccentric demand is small, so if you can’t get a catch in, the loss can be made up elsewhere.
Typically, two to three sets of three to four reps is enough to really drive high quality work in without ruining an athlete later in the week. I have found that clusters not only keep athletes feeling fresh afterwards, they don’t trash the athlete so another high intensity session is not possible. Due to the intense neural work, some athletes may feel flat, but they don’t have the car accident feel that straight sets seem to do, especially with the tightness or stiffness the next day from DOMS. Rest periods are typically longer on the sets (3-5 minutes) but shorter (20-30 seconds) between singles. As the athlete is more skilled I tend to use 30 seconds, but this is just a personal preference.
All of the workouts can be modified to meet the needs of the athlete, and are just the tip of the iceberg. Try creating your own by replicating the workouts that show experienced lifters; many of the studies are actually good programs.
Block Power Snatches for Doubles
My last workout is perhaps the biggest staple—block snatches for doubles—but in this case as a cluster option. I love snatches from blocks as it saves the stress on the lower back and allows for great force-generation capabilities because no rocking action of a hang can cheat the rep. I like keeping the set rest periods shorter (two to three minutes) while keeping the rest between clusters very high, usually up to a full minute or longer. Rest between repetitions is typically 20-40 seconds, but longer is fine. The key is to find the right blend of rest that paces the workout so each rep has high output. It’s ok to extend cluster time as the workout unfolds. Experiment with cluster set rest and the rest between rep for optimal workout performance.
Video 3: Above-the-knee power snatches are fast off the start and provide a way to load the legs and spare the lower back. Athletes using blocks should make sure they know how below-the-knee options interact with their body, as the rhythm is different.
I typically work the athlete up to six to eight total reps per set, and perform two to three sets per workout. It’s a serious workload, but the use of blocks and a lighter percentage makes it a sensible high-power session. The numbers change as the athlete gets more advanced, and guide the process by speed and power, not by load.
Like the clean workout listed above, barbell tracking from either the technical path of the bar or a proxy measure, such as total distance of the action, is a value to the coach. Other measures such as RFD are not appropriate unless the lift is above the knee and athletes are just working on gross pulling and not worrying about any temporal mechanics.
Give Cluster Training a Fair Try
Don’t bother using cluster training for just a few weeks, as it takes a few months for it to show up anywhere. I found clusters reps took two full seasons to see something that was undeniable, and a few months of it just looked like good training, not a remarkable technique. The research may show a statistical significance in weeks, but a full performance benefit may take a year to surface.
If you use cluster workouts with your athletes, expect a lot of focus and mental lockdown for the session because the method keeps an athlete on their toes. I have found that long stretches of rest for high output is gold, but adding more science and application, clusters are the diamonds of training.