Photography by Michael Neveux

Wild and crazy training methods seem to come out every other week these days. Whether it’s static-contraction training, superslow mo or one-set-per-week workouts, the get-big fads go in and out of style faster than bell-bottom jeans and capri pants for guys.

Much of that is probably due to the explosion of information available on the Internet. Unfortunately, the explosion has included a lot of collateral damage—unscientific and downright bad training methods being popularized.

What if I were to tell you that one method of training has been proven to cause significant hypertrophy in numerous scientific studies? That it involved lifting weights that are about half the poundage you’d typically use? Then what if I told you that the method stimulates growth by reducing blood flow to the muscles you’re working? You’d probably say I’m an idiot and turn the page—but then you’d remember that I mentioned scientific research. Ah, you are interested. The method is called occlusive training, and it’s been around for a while, racking up unbelievable results backed by solid data. For some reason nobody’s jumped on the concept, but I’m here to tell you how you can integrate it into your current training to help slap on some big-time muscle.

Research on Occlusive Training

Studies show that moderate-intensity training (60 to 85 percent of one-rep maximum), with short rest periods (one minute) yields optimal strength and hypertrophy gains. Some scientists suggest that an intensity threshold of 60 percent of 1RM is required to stimulate hypertrophy and strength gains. That renders low-intensity training—20 to 40 percent of 1RM—obsolete in strength training and bodybuilding. Two primary mechanisms by which moderate-intensity training stimulates growth are greater recruitment of muscle fibers and the accumulation of metabolites—lactic acid, for instance—that serve as signaling molecules for anabolic hormones and other growth factors.

It’s reasonable to assume that if athletes could simulate the conditions produced by moderate-intensity training, they’d get similar results. Well, assume your brains out, for it is entirely possible, and you won’t even have to train heavy to do it. Researchers have found that occluding blood to the muscles during low-intensity physical activity can produce an anabolic response equal to, or perhaps greater than, moderate-intensity exercise. Occlusion training has also benefited the young and the elderly, regardless of training status.

In a short-term study investigating the effects of blood-occlusion training on protein synthesis—a.k.a. muscle anabolism—six healthy male subjects, average age 32, performed two sessions of low-intensity leg extensions for four sets, working at 20 percent of 1RM and taking 30 seconds of rest between sets. They exercised with and without a blood pressure cuff wrapped around their thigh and inflated to 200 mm Hg. The cuff increased blood pressure and impeded blood flow. Protein synthesis increased by nearly 50 percent following occlusion training but was unchanged in the control condition.

Longer-term studies have shown several advantageous adaptations as a result of occlusion training. A research team looked into the effects of performing leg extensions twice weekly for two months in elite rugby players. The athletes were separated into three groups: those doing leg extensions with blood occlusion of the thighs at 50 percent of 1RM, those doing leg extensions without blood occlusion at 50 percent 1RM and a control group doing no exercise. Strength and quadriceps size improved by 14 percent and 12 percent, respectively, in the blood-occlusion group, while neither increased in the nonocclusion or control groups.

Amazingly, this method works regardless of the age of the trainee. One study had 24 healthy elderly women, average age 58, perform dumbbell curls twice weekly for 16 weeks. The subjects were separated into groups: one doing low-intensity exercise—at 30 to 50 percent of 1RM—with occlusion, another doing low-intensity exercise without occlusion and a third doing moderate-intensity exercise without occlusion. Muscle mass was greater in the biceps brachii and brachialis after occlusion training (20.3 and 17.8 percent, respectively) than nonocclusion training (6.9 and 3.8 percent), and occlusion training tended to produce greater hypertrophy gains than the moderate-intensity training (18.4 and 11.8 percent).

More recently, scientists have found 6 percent increases in thigh muscle along with 8 to 10 percent increases in 1RM and isometric strength, respectively, in young men who walked for two five-minute bouts with occlusion, six days a week for three weeks. Conversely, no increases in either muscle mass or strength were observed in the control condition.

Another interesting finding is that occlusion training may improve the conditioned look of a bodybuilder by increasing vascularity. Some studies reveal increased vascular endothelial growth factor, which stimulates the growth and formation of new blood vessels. Overall occlusion training leads to bigger, stronger and better-conditioned muscles. ALL Mechanisms of Action

Several mechanisms may explain the exciting growth and strength adaptations that occur with blood-occlusion training. The first is related to fiber recruitment. One of the major reasons high-intensity training works so well is that it forces trainees to recruit the larger fast-twitch muscle fibers, the fibers that have the greatest capacity for growth. Studies have demonstrated an increase in fiber activation equivalent to high-intensity training, as measured by electromyographic activity, greater whole-body oxygen uptake and increased depletion of ATP from muscle tissue. Likely, the fatigue in the small slow-twitch muscle fibers in a low-oxygen (no blood flow) environment causes increased motor unit recruitment, as well as inhibiting muscular contraction in those fibers due to lactic acid buildup. As fatigue sets in, the body is forced to recruit larger muscle fibers to maintain force output.

A second major mechanism is related to occlusion training’s stimulation of anabolic hormones. Occlusion during leg extensions increases blood growth hormone by as much as 290 percent. To put that in perspective, traditional high-intensity training has resulted in up to 100 percent increases in GH.

The explanation lies within the finding that low-oxygen environments increase lactic acid production, while the occlusion traps it inside the muscle tissue. Past studies show strong correlations between blood lactic acid and GH, a phenomenon most likely explained by increasing acidity in the blood. Moreover, research suggests that the accumulation of lactic acid in fast-twitch muscle fibers is sensed by local chemical receptors and carried back to the hypothalamus, which ups the rate of GH secretion.

Myostatin has received a great deal of press over the past decade, and rightly so, as its upregulation stunts muscle growth by inhibiting the addition of nuclei capable of supporting further growth to muscle fiber. That factor was recently found to be inhibited in the quadriceps following short-duration occlusion training.

What really makes the technique unique is its ability to stimulate muscle growth without a detectable rise in muscle tissue damage. That’s amazing, as many scientists suggest that muscle damage is essential to trigger growth. Finally, a number of studies have revealed that cortisol may not increase after occlusion training. By contrast, cortisol rises relative to increasing intensity and is responsible not only for myostatin upregulation but also for overtraining and the breakdown of muscle tissue.

To recap, blood-occlusion training can increase motor unit recruitment, raise anabolic hormones and suppress local negative regulators of muscle growth. It’s also free from many of the negative side effects of training, such as increased muscle damage and unfavorable catabolic hormone increases.

Practical Applications

“Okay,” you’re saying. “I get it. Occlusion training works. Tell me how to do it already.” After reviewing the studies and doing some experimentation, I’ve devised a few protocols. Unfortunately, occlusive training is feasible only for the arms, legs and possibly shoulders, as it would be nearly impossible to occlude blood flow to the chest and back muscles without suffocating.

You must place more pressure on the limb you’re trying to occlude than the blood pressure of that area. That’s how a tourniquet works. In the lab, researchers used a specialized blood pressure cuff to achieve a diastolic blood pressure of around 200 mm Hg—probably overkill, as most people have diastolic pressure of far less than that. Most people’s readings are anywhere from 110 to 140 mm Hg.

You can use several different methods to occlude a muscle:

1) Buy the actual cuffs used for kaatsu training. Unfortunately, they’re hard to find, as they’re made in Japan and are on the expensive side.

2) Use a blood pressure cuff. That enables you to get a precise measure of the pressure needed. Still, an actual blood pressure cuff may be a bit awkward to use in the gym. People may look at you as if your fly is open.

3) Use a Velcro-equipped lifting belt. They’re inexpensive, easy to find and quite fast and easy to use. The downsides: You’ll probably be able to use it only for legs, as the belt will be too big to properly occlude your arms. You also won’t know exactly how much blood flow you’re blocking the way you do with a pressure cuff. A quick and dirty method of finding out if it’s tight enough is to put the belt around your leg tightly, then stand up and see if you feel a strong “pump” and slight numbness after about 60 seconds. If you do, it should be tight enough.

4) Use powerlifting knee wraps. They’re inexpensive and readily available and can occlude the arms or legs. The downside is that it takes time to wrap your limbs, and if they’re not tight enough, you’ll spend more time rewrapping. Additionally, it can be more difficult to get them on both limbs with the same degree of occlusion; you don’t want to occlude one limb more than the other if you’re wrapping them both at the same time. Unilateral training is an easy fix: Wrap one limb, do your sets, and then wrap the other limb.

5) Apply a compression wrap—typically used for injuries—tightly around the trained muscle. They’re particularly effective for small muscle groups such as calves, biceps and forearms, but they can be rather difficult to wrap around the arms. Having someone assist in the wrapping is helpful. Now that we’ve covered how to occlude a muscle, the next obvious question is which exercises, sets, reps, etc., you should use. I suggest adding occlusion work at the end of a typical leg or arm day. It should take only five to 10 minutes, but be forewarned: Occlusion training is very taxing.

First set: 30 reps with 20 percent of one-rep max

Three subsequent sets: 15 reps with 20 percent of one-rep max, taking 30 seconds of rest between sets

Four sets to failure with 50 percent of one-rep max, taking 30 seconds of rest between sets

Four sets to failure with 50 percent one-rep max, taking one minute of rest between sets

Note: Do not remove the occlusion device until you’ve completed all of the sets. You may be looking at those poundages and thinking this is some kind of joke. Go ahead and laugh. You’ll be cursing soon enough.

If you’ve occluded the muscle properly, you’ll find that the first few reps feel very easy, like normal. As the set progresses, however, you’ll find that you hit a wall very fast because the slow-twitch fibers have been prefatigued by the lack of oxygen. The rest between sets will do very little to help you recover. The pump will be intense, but so will the pain if you’re working correctly—so intense that you’ll want to remove the occlusion after every set.

A Cautionary Tale

It’s important to note that while occlusion training has proven to be an extremely effective agent of hypertrophy, more is not necessarily better. Safety first: Do not occlude any muscle for more than 10 minutes at a time. Long periods of occlusion can put you at risk for necrosis or embolism. The protocols provided here are for very short periods and are very low risk. Even so, as with any training program, it’s wise to consult a doctor before starting. If you want to do more occlusion training, you might try using the protocols multiple times in the same workout, releasing the occlusion between bouts. For example, you could do four sets to failure with 50 percent of your one-rep max, resting one minute in between sets. After those four sets release the occlusion, rest for a few minutes, and then repeat the protocol.

While most exercises are suitable for occlusion training, I recommend that you stay away from free-weight squats, as the occlusion may make it more difficult to balance the weight properly. Keep in mind that occlusion training is no replacement for heavy lifting, which should be an important part of every serious bodybuilder’s arsenal. It builds a strength base that is necessary in order to stimulate significant hypertrophy over time. It also causes significant muscle tissue damage, which itself is a very powerful signal for growth. You should use occlusive training as an adjunct to heavy training, and you can use it with great success during deloading periods.

It’s just too hard on the joints to lift heavy every day for years on end. You need periods of reduced load to enable your joints to heal and your state of mind to recuperate. Historically, that’s meant sacrificing short-term gains over a few weeks’ time for long-term benefit. With occlusive training, however, you can achieve significant hypertrophy while lifting light.

Note: Maybe you don’t need a tourniquet at all. For another view of occusion training, see “Was Charles Atlas Right?” on page 125.

Editor’s note: Layne Norton has a B.S. in biochemistry and is a Ph.D. candidate in nutritional science. He’s a professional drug-free competitive bodybuilder in the IFPA and NGA. His Web site is www.BioLayne.com. IM References

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