Absolute Mass

We all know building a muscular body takes time, but if you want to speed things up and kickstart some serious hypertrophy, you must make intelligent use of two core muscle-building concepts: absolute strength and absolute volume.

Absolute strength is 66% correlated to functional mass. The stronger you are, the larger the fiber cross-sectional area (size). Absolute volume (non-functional mass) means the more cellular muscle volume you can pack in, the larger the size of the muscle. Cell volume leads to a greater stretch-induced muscle hypertrophy without neuromuscular-induced stimulation.

How can you take advantage of these "absolutes"? Variable Cluster Training!

VCT: Variable Cluster Training

Generally speaking, "clustering" refers to the rest-pause method where you use a heavy load and do single reps with short rest intervals. The concept of cluster training was first introduced to me by Charles Poliquin. Cluster training is a form of weighted interval training that maximizes the strength and cell volume training effect in the same workout session.

Here's an example. In traditional resistance training, the trainee executes a workout using six sets of six reps to failure and resting three minutes between sets. In order to complete this, the lifter must choose a load equal to 80% of his one-rep maximum. This equals a total of 36 reps, 80% of max, in roughly 25 minutes.

Now, there are two types of cluster training, intensive and extensive. With intensive cluster training, you maximize the strength component by using comparatively higher loads, 85% 1RM, performed intermittently with a 30-second rest period between each rep. (1)

A cluster set of reps then is equal to six single reps, each spaced with a brief pause (1+1+1+1+1+1). This brief pause partially restores the nervous system which allows 2 to 5% additional load to be used. So six sets of six "cluster" reps at 85% intensity and three minutes between sets equates to the same 36 reps in 25 minutes, but 5% more work load. This strategy is performed on major lifts with heavier loads, resulting in larger, faster motor units being recruited.

Extensive cluster training maximizes the volume component by using similar loads as our first example, 80% 1RM, performed intermittently with a 10-second rest between each rep. In contrast, the brief pause facilitates the nervous system into allowing two or three additional reps. So six sets of eight intermittent reps at 80% intensity and three minutes between sets equals 48 reps in roughly 25 minutes at 80% intensity. That's an increase of 25% more work volume!

The pause facilitates the nervous system due to manipulation of physiological effects. Local lactate accumulation is allowed to dissipate. This mitigates the cellular "shut down" of energy system enzymes normally occurring in sub-maximal training.

Oxygen debt during the intensive cluster portion is kept to a minimum. This permits a longer recruitment of the fastest fibers. Furthermore, a long eccentric (negative) tempo of up to five seconds will prolong tension time on the fastest fibers. A longer, 30 second rest between single reps is used in this case.

Oxygen debt during the extensive cluster portion, however, is maximized. This forces a recruitment of the slower, oxygen efficient fibers. A long concentric tempo of up to five seconds will prolong slow fiber tension time and increase blood lactate, leading to non-functional hypertrophy (2). A shorter, 10-second rest between single reps is used in this case.

Due to higher metabolic demand and the need to minimize lactate, the intensive cluster is always performed first in the workout order.

Dropping Acid

As you've probably noticed, lactic acid, an energy byproduct of muscle metabolism, is of keen importance in both the ability to harness fast twitch fibers and the perception of difficulty. (3) Like a kid with a credit card, it must be constantly observed, otherwise it can crush your strength gains.

What about ways to control lactic acid and lactate buildup chemically? It can easily be done. Acid-base manipulation has been extensively researched, mostly in endurance events to prolong exercise time to exhaustion. Studies by Hermansen, Ownes and Sahlin show an increase of up to 15%. Buffering technology is beneficial in strength training (1-5 RM) because any buildup of lactate is detrimental to maximum strength. However, the jury is still out on whether less acid benefits bodybuilding/hypertrophy training (6-15 RM).

Why the controversy? Local acid buildup, the factor you're trying to avoid in strength training, leads to "muscle swoll": lactic acid buildup in the muscle cell which signals the body to super-compensate energy substrates (glycogen, phosphates etc.). This is the basis for non-contractile mass gains.

So which is better, fewer reps and quicker stimulus, or one to two more reps but the same end point? My personal view is that much depends on the individual's training and lifestyle. If a person is training high volume on a low carb diet or taking caffeine, then the blood is always going to be unusually acidic. Acidity can be spotted by a buildup of mouth sores and a faster breathing rate.

So toward the end of the week when dehydration and fatigue are factors, I have my athletes minimize the acid-containing foods and supplements and take baking soda up to three times per day. An exception may be the new R form of alpha lipoic acid. This antioxidant appears to increase mitochondrial ATP release, thus providing energy for extra reps. Yet being an acid, blood acidity may increase and still stimulate mass gains. Only time will tell.

With this in mind, I recommend the use of an acid buffer drink prior to intensive cluster training. This is simply one tablespoon of baking soda with water. After the strength portion has been completed and prior to extensive clustering, consume 200-400 mg. R- alpha lipoic acid.

The Animalistic Squad Busting Routine

Let's put all that info to work now in this sample leg training program. This program is designed to be performed once every five days or six times per month. Additional calf training may be added to suit your personal needs.

Execution Guidelines

All reps must be completed; that's why I recommend starting the first couple of sessions with a slightly lighter load. Using this approach, you'll be able to increase the load 2% to 5% every session.

During the intensive, heavy portion, rack the load in between reps and rest 30 seconds. During the extensive, moderate load part, hold the loads isometrically between the concentric and eccentric portions. This constitutes your 10 second "rest!"

Intensive Portion of Workout

A1) Barbell Hack Squat – Elevate your heels on the edges of two 25 pound plates, spaced 4 inches apart. Feet should be shoulder-width apart. Using wrist straps, grasp the barbell slightly wider than shoulder-width. The barbell is on the floor behind your heels.

Using your vastus medials quad muscles and a straight back, lift the barbell by extending the knees. To squat the bar, shoot your knees forward over your toes and then lower your hips until the back arch is compromised.

Sets: 5 clusters*

Reps: (5 x 1) start session one at 78.5% 1RM

Tempo: 50X0**

Rest between reps: 30 seconds

Rest before A2: 2 minutes

*In other words, you'll be doing 5 single reps of hack squats, pausing a full 30-seconds in-between each rep. Upon completion of this cluster set, you'll do a cluster set of Seated Single Leg Curls (described below) before doing your second cluster set (of five).

**See the FAQ if you're unfamiliar with tempo prescriptions.

A2) Seated Single Leg Curls –
On this exercise, the concentric contraction is minimized by lifting with two legs and lowering (eccentric) with one.

Tips: Place the feet in a neutral position, shoulder-width apart and plantar flex (point) the toes. Be careful not to lift or shift the hips toward your strong side.

Sets: 5 clusters

Reps: (5 x 1) start session one at 72.5% 1RM

Tempo: 50X0

Rest between reps: 30 seconds

Rest before resuming A1: 2 minutes

Extensive Portion of Workout

B1) Wide Stance Leg Press – The feet are positioned wider than shoulder-width and splayed out at 45 degrees.

Flex the knees and lower the platform so that your knees contact your shoulders. Pause momentarily to let the stored elastic energy (plyometric effect) dissipate. Next, slowly extend the knees to a soft lockout position and pause briefly again.

Sets: 3 clusters*

Reps: (12 x 1) start session one at 70% 1RM

Tempo: 2151

Rest between reps: 10 seconds

Rest before B2: 1.5 minutes

*In other words, you'll be doing 12 single reps of leg presses, pausing a full 10 seconds in-between each rep. Upon completion of this cluster set, you'll do a cluster set of Semi-Stiff Legged Deadlifts (described below) before doing your second cluster set (of three).

B2) Semi-Stiff Legged Deadlift – Grasp the bar with a clean, pronated grip, elbows locked, knees bent 10 degrees, feet narrower than shoulder-width and toed out slightly.

Lowering: Using an arched back, lower the bar along the body in constant contact with the thighs and shins. Drive the hips on a horizontal line to the posterior. Keep the knees iso-angular at all times. Lower until the torso is parallel to the ground.

Next, in one uniform motion, raise the bar by contracting the glutes and hams. Extend the spine completely past the vertical line. Lower the bar along the body and repeat. Keep the chin retracted and head in a neutral position.

Sets: 3 clusters

Reps: (12 x 1) start session one at 70% 1RM

Tempo: 1050

Rest between reps: 10 seconds

Rest before B1: 1.5 minutes

C) Leg Extensions – I'm sure everyone can figure this one out. The two tips I like to give are to keep the feet neutral at all times and start relatively light. This will keep your blood pressure and hips from soaring and your tempo somewhat rhythmic.

Sets: 3 clusters

Reps: (12 x 1) start session one at 70% 1RM

Tempo: 1050

Rest between reps: 10 seconds

Rest before repeating C: 1 minute


All this might seem a little confusing just reading it, but it'll all come together when you try it in the gym.

Want some rapid mass gains? Try Variable Cluster Training today!


1. Mel C. Siff, Yuri V Verkhoshansky Supertraining 1999; Bodybuilding and other strength training methods, Sec 7.1, 396-97.

2. Different effects of concentric and eccentric muscle actions on plasma volume Robert J Durand et al. The Journal of Strength and Conditioning Research Vol. 17 Number 3 Aug. 2003 541-48.

3. The Journal of Strength and Conditioning Research Vol. 16 Number 4 Nov. 2002 491-499.