When a well-timed blow floors a boxer the fight isn't always over. More often than not, he'll come to his senses, stagger to his feet and steady himself for another bout of giving and taking punishment. And depending on the organization governing the fight, he'll often get a 10-second grace period or a standing eight count, giving him just enough time to compose himself and come back swinging.
Okay, so maybe you've never gone toe-to-toe with 12-ounce gloves on. But if you've stood with a loaded barbell on your back and squatted below parallel for rep after rep until you couldn't force yourself back up out of the hole, you have some idea of what it's like to handle a Tyson-like pummeling. What you may have noticed - particularly if you've experimented with the rest-pause intensity technique, in which you take a very short break during your set only to continue right back on - is that even though a heavy set of squats can leave your legs as shaky as those of a clock-cleaned prizefighter, your ability to lift heavy returns fairly quickly. In fact, after just a few seconds of rest you're often able to continue a set well past the initial point of failure. And while rest-pause is a great way to take advantage of this restored potential, a similar method, called cluster training, lets you embark on a significantly heavier set from the first rep and extend it into rep ranges that would normally be out of your reach to maximize your neural response and encourage greater growth. The trick is simply a matter of timing.
Extend Your Set
"Cluster training is simply using non-traditional set-and-rep schemes that contain built-in pauses," says Bret Contreras, who trains both bodybuilders and strength athletes in Scottsdale, Arizona. The idea, of course, is to lift a heavier weight - about 85% of your 1 rep maximum - for more reps than you normally would when following a typical hypertrophy routine. Whereas a standard rep count for hypertrophy tends to fall between 8-12 reps per set with a weight that forces failure somewhere within that range, cluster training lets you use a heavier weight (typically one that you'd be able to lift for no more than 5 reps) and pushes each set into a hypertrophy rep range (meaning you're doing 8-12 reps with a weight that's so heavy you'd normally fail in just 5). In short, you're doing more reps - far more - with a heavy weight to place significantly more stress on your target muscles.
The concept of cluster training is fairly straightforward, but the sheer number of available cluster variations - from antagonistic clusters to Mike Mentzer's cluster method - could easily sway some bodybuilders from incorporating them into their routines. So to focus your energy on lifting heavy instead of wasting time deciphering obscure training science, we're going to stick with one cluster method in particular that's especially promising. It's a variation called Extended 5's, developed by Christian Thibaudeau.
The goal behind an Extended 5's cluster is to perform a set of 10 reps with a weight that you would normally lift for only 5 reps. The method is similar to rest-pause, an intensity technique in which you complete a set and then, after a very brief rest, continue to perform reps until you reach failure a second and third time, extending the set beyond your usual point of failure. This way, you'll more effectively tax the target muscle group and encourage growth. The main difference between cluster training and rest-pause, however, is that rest-pause is often used at the end of a standard set performed with a moderate weight (e.g., a set of 5-6 reps using a lifter's 8-10 rep maximum), and the initial rest period is undertaken without going to muscle failure. Cluster training has pauses built in throughout the set, allowing you to use significantly heavier weights, which ensures you'll reach muscle failure on each one.
The science behind cluster training isn't anecdotal; in fact, it relies on the body's normal physiological response of swiftly restoring adenosine triphosphate (ATP), a molecule that the body uses to transport every activity you undertake, but it plays an especially prominent role in heavy, short bursts of resistance training, where it combines with creatine phosphate to provide short-term energy for high-intensity work. The beauty of cluster training, as with rest-pause, is that the built-in 7-12 second rest provides just enough time for you to restore enough ATP to continue on with your heavy set, effectively increasing both the intensity and the volume of your workout.
By the Numbers
A typical set in Extended 5's cluster training would go as follows:
- Load the bar with your 5RM (that's a weight with which you can perform only 5 reps, typically about 85% of your 1RM) and do 5 reps.
- Rack the bar and rest for no more than 7-12 seconds.
- Immediately get back under the bar and do another 2-3 reps.
- Rack and repeat the 7-12 second rest.
- Complete a final 2-3 reps to finish the cluster set.
So, it's
5RM x 5, 7-12 second rest, 2-3 reps, 7-12 sec. rest, 2-3 reps.
When you're finished you'll have done 10 reps (and hit the exact center of the typical hypertrophy rep range) with a weight that you could usually lift for only 5 reps. Form there, rest for 3-5 minutes before starting your next cluster set.
To get cluster training right, you'll need to be precise when you load the bar. Go
too heavy and even if you manage to make it to 5 reps, that 7-12 second pause won't allow enough ATP recovery for you to finish the set. Pick a weight that's too
light and you'll be sacrificing the intensity component of cluster training. Generally, if you can make it past those first 5 reps without pausing, you've gone too light. To estimate your 5RM on just about any exercise refer to one of the multitude of max calculators online.
Whenever you're lifting within ranges that optimize strength (anywhere from 85-100% of your 1RM, or more simply when you can do just six or fewer reps), you'll need to be vigilant about overworking - especially when you're applying cluster training or other intensity methods to a compound, big-stress movement like the squat. For this reason, I recommend you hit legs only once a week, with the focus switching from anterior-dominant (quadriceps) movements to posterior-dominant (hamstrings and glutes) movements each week for four weeks before deloading. While some bodybuilders prefer to separate their leg training over two days, that isn't recommended for cluster training. When you're aiming for intensity, a "less is more" approach is often best. Hit it hard and then head home. After the fourth week, you should scale back your intensity and take at least a week off from cluster training to give yourself a chance to recover, refresh, and reload. Deload to reload.
In Your Workout
Now that you understand the basic mechanics behind cluster training, let's consider how it fits into your leg-day routine. As Contreras points out, "All leg exercises can be clustered, but since you're aiming for neural adaptations it makes sense to use heavy compound movements rather than lighter isolation movements." For that reason your cluster training will revolve around the front and back barbell squat, two of the best lower-body mass-builders. Because you'll have to quickly rack and un-rack the bar to take full advantage of your brief rest periods, be sure you're set up to do so - and be sure to take precautions covering the possibility of missing a target rep.
Contreras insists that individuals should "always do clusters first in a workout, right after a general dynamic warmup and a specific warmup on the exercise at hand." The reasoning here is simple: You'll be able to lift the most weight and create a maximal neural response while you're still fresh. And it should come as no surprise that your 5RM on the squat will be significantly less after you've performed other multi-joint or isolation exercises than it would if you did squats at the beginning of your workout.
You also shouldn't be applying clusters to more than one exercise. "Clusters should be reserved for just one movement per workout," Contreras says. "Then you can add exercises that focus more on metabolic stress and cellular swelling," otherwise known as hypertrophy-focused single-joint movements. For these accessory lifts (see the routine layout at end of article) you'll follow basic set-and-rep schemes with standard breaks of about two minutes between each working set.
In Your Corner
As with any hardcore training method, safety should be first on your list when you're hitting heavy clusters. To avoid injury, always squat with a competent squatter or in a rack with properly adjusted catchers. As mentioned earlier, efficiency in racking and un-racking the bar will be key to fully utilizing on this method.
When training for either strength of hypertrophy (or, in the case of cluster training, both), intensity is your best friend. But always remember that your goal should be to find a balance between training intensity and injury prevention and avoidance. Listen closely to your body and be vigilant about keeping perfect form even when the going gets tough.
The Best of the Rest
The squat may be the king of full-body mass builders, but it's just the tip of the iceberg when it comes to cluster-ready movements. To break though plateaus in other stagnant bodyparts, try applying the same cluster-training template to the following heavy compound movements, each of which allows for quick, convenient rest periods.
Legs: deadlift, Romanian deadlift, leg press.
Back: weighted pullup, lat pulldown.
Chest: bench press, incline bench press.
Triceps: weighted dip close grip bench press.
Sample Leg Training Cluster Routine
Week 1 - Rear Thigh Focus
Back Squat
3x5 warmup (40%, 50%, 60% of 1 RM) with 1 min. rests.
3x10 (85%) 3-5 min. rests. Perform as a cluster set by doing 5 reps, racking the bar and resting for 7-12 seconds, performing 2-3 more reps, racking and resting again for 7-12 seconds, and then completing a final 2-3 reps for 10 reps total. Rest and complete the sequence three more times.
Reverse Hack Squat
3x10, regular reps, 2 min. rests.
Leg Press
3x10.
One Leg Lying Leg Curl
3x10.
Week 2 - Front Thigh Focus
Barbell Front Squat
3x5 warmup (40%, 50%, 60% of 1 RM) with 1 min. rests.
3x10
(85%) 3-5 min. rests. Perform as a cluster set by doing 5 reps, racking
the bar and resting for 7-12 seconds, performing 2-3 more reps, racking
and resting again for 7-12 seconds, and then completing a final 2-3 reps
for 10 reps total. Rest and complete the sequence three more times.
Leg Press
3x10.
Walking Barbell Lunge
3x10.
Leg Extension
3x19.
Week 3 - Rear Thigh Focus
Repeat Week 1.
Week 4 - Front Thigh Focus
Repeat Week 2.
