Occlusion, Ischemia, and ‘The Pump’

It’s in vogue these days to hate on bodybuilding and the training methods bodybuilders use. The trend these days is to play up the role of strength-based training and ‘functional’ (sic) training methods, getting away from the older bodybuilding culture that’s dominated the popular conception of weight-lifting since at least the 1960s.

It used to be all about the pump, about feeling and shaping and all of that. These days, it’s more about ensuring proper movement, developing well-rounded fitness, and putting strength-based methods at the center of that balanced program. Specialized goals are then added to that framework, in the same sense that your house can look different from your neighbors even if they have the same blueprints.

I can’t say there’s a real problem with this, because that’s the gist of my philosophy, and in general I think that’s how things should be done. However, this takes us to a dangerous place, a thought process that can be counterproductive; in other words, you don’t want to throw out the baby with the bathwater.

This includes even the most Bro-ish of bodybuilding techniques. I can’t lie here, either. I’ve been guilty of this mentality too; or it least it might seem like it with my pro-strength, pro-rationality views. The reality’s a little different, but people used to thinking in black/white terms tend to label everyone else as thinking in black/white terms too.

Unlike most hardliners, who pick a position and stick with it regardless of evidence or outcomes, I think there’s some utility in almost any training style or approach. And yes, that even includes bodybuilding. It’s too easy these days to write off all of traditional bodybuilding as flawed, outdated, and based on pure mythology.

I think that’s premature, though. And I want to be clear: I’m specifically talking about training methods usually associated with bodybuilding – emphasis on ‘pumping’ the muscle, focusing on muscle isolation and shaping, things like that.

I discussed this to some degree in Maximum Muscle, but I was reminded of this subject yesterday, so I thought I’d write something up. The modern paradigm would write off bodybuilding in favor of ‘functional’ approaches. In response, I point out that ‘functionality’ is entirely dependent on context. For a bodybuilder seeking bigger muscles, anything that makes the muscles grow is the definition of functional.

Please let that soak in. ‘Functional training’ is not flipping tires, climbing ropes, doing cleans with the worst possible form, or kipping pullups. Functional training is whatever improves your functionality in a given goal.

KAATSU!!!! and Occlusion Training

Over in Japan the last 10, 15 years or so, they’ve been experimenting with something called ‘occlusion training’ or ‘ischemic training’. If you don’t pay attention to the research journals, you’ve probably never heard of this, but it goes by the name Kaatsu, which is probably Japanese for ‘powerful cuff of great oxygen deprivation honor’.

Anyway, what they do is occlude the flow of blood into the muscle with these big tight cuffs. It’s like when the doctor takes your blood pressure; imagine how that feels, with the tight cuff around your arm. Not always pleasant, but that’s what occlusion feels like.

These guys have been finding that if you block the flow of blood into the muscle – occlusion of blood flow – that very light loads can suddenly stimulate growth and strength gains. When I say light, I mean light; they’re talking on the order of 30% of the 1RM, where we normally expect to see weights in the 70-90% range used to stimulate growth.

I’ve gone over all that before so I’m not going to rehash the explanations, but that’s very unusual to see actual hypertrophy gains coming from loads that light.

My pet hypothesis, which seems to be backed up in the research, is that there’s a neuromuscular effect going in on response to the acute hypoxia (that is, lack of oxygen). Since the working muscles can’t refuel themselves, they’re fatiguing prematurely in response to even a 30% weight.

When you train to fatigue at 80% 1RM, you’re doing basically the same thing – you’re fatiguing the working muscles, and fatigue translates into neurological changes in how fibers are being recruited. Your nervous system is trying to take up the slack by activating more motor units.

In research, this state of fatigue is called ischemia; the muscle fibers tire out and tend to stiffen up. It’s thought that ischemia contributes to both neurological strength gains (via those recruitment changes) and the growth process by making the fibers more susceptible to eccentric overload on any subsequent reps.

In a way, we can think of occlusion as cutting out the middle man. Instead of requiring a heavy load to reach fatigue and ischemia, you just cut off the blood supply; instant ischemia, and now even light weights represent a sufficient overload to stimulate strength and muscle-mass gains.

Now as I mentioned, Kaatsu research has been using occlusion cuffs – a tourniquet or something like that to cut off the flow of blood into the muscle for the training. It’s not hard to imagine where the limitations come into this. You can tie off an arm or a leg pretty easily; anything in the torso is out of luck without some creative surgical methods.

My point here has never been to endorse that particular technique (although you certainly can). What I want to do is look at the underlying physiological process, and note that there is a mechanism to explain how lighter, but longer-duration and more fatiguing methods can potentially stimulate growth. The outcome of occlusion and the direct stimulation of ischemia is pretty compelling, regardless of how you create that effect.

Note that occlusion/ischemic training isn’t actually getting away from the basic principle of tension-time overload. In normal weight training, we reach a compromise in tension-time by using moderate weights and moderate volumes of work. Occlusion/ischemic training simply represents a different configuration of tension-time; by making the muscles more ‘receptive’ to lighter tensions and then extending the duration of work.

A New Use for ‘Pump’ Training

This brings me to the point of the article. We’re limited in how we can externally stimulate occlusion. But tight cuffs aren’t the only way to cut off blood flow.

Muscle contractions do it too. And with that, you can probably see where I’m going here.

How is it that bodybuilders have always been reputed to train? They’re all about ‘squeezing’ and ‘contracting’ the muscles, about really making sure to ‘feel’ the muscle working. Bodybuilders love their slow, controlled tempos, and really pumping up the muscle with all sorts of extended-tension methods. The failure-training meme got started with this, even, and who can forget Arnold’s obsession with the pump (no matter how much we drink…)?

Because of the occlusion research, there’s now a real basis for explaining how those methods produce results. If you’re a pro-strength hardliner, you’re going to scoff and say it’s ‘virtual’ muscle. Well, that’s kinda true depending on your point of view.

Based on the Kaatsu research, muscle fiber CSA does increase; that is, the muscle does grow. However, unsurprisingly, it seems that most of the CSA gains are the result of so-called sarcoplasmic hypertrophy.

That is, water, glycogen, and the various life-supporting enzymes and organelles of the cellular machinery increase in volume, as opposed to the contractile proteins. This is ‘non-functional’ hypertrophy. But if you’re a bodybuilder, who cares? A bigger muscle is a bigger muscle.

It’s often suggested that the more ’rounded’ or ‘puffier’ look of bodybuilder’s muscles is due to sarcoplasmic hypertrophy. There may actually be some truth to this given that bodybuilders are prone to high-volume, slow-tempo, post-fatigue kinds of training.

What I question, as I always have, is the contribution of such methods to your long-term progress. I’ll discuss that in just a minute.

Occlusion/Ischemic Training Methods

As far as creating the occlusion effect, and deliberately triggering ischemia, that’s easy enough to do. And if the Kaatsu stuff is anything to go by, it doesn’t require anything heavy. To that end, everything here can be done with weights (or resistance if you prefer the broader term; some of these methods are uniquely suited for machines) in the range of 30-50% of a 1RM load. Light and slow is the name of the game.

Slow Tempo and Peak Contraction Sets – Basically, this is just the ‘pumping’ style of training that Arnold was famous for. Slow, deliberate reps, focusing on the ‘squeeze’ of the contraction. The goal here is indeed to keep tension on the working muscles; no relaxation at the top or bottom.

Timed Partials – I say ‘timed’ in the sense that you don’t count reps. You just set aside say 60 seconds, or 90 seconds, and just keep moving slowly over a shortened ROM until the time’s up. This will hurt, especially if you’re not used to it.

Extended Isometrics – And on that same note, there’s really no reason you even have to move the bar. Load up your implement of choice with a 30-50% load, move into position, and just hold it. You could even combine it with the timed partials by holding at 2-3 positions and slowly moving between them, alternating isometric holds and slow partial reps.

Basically any ‘post-fatigue’ bodybuilding methods – Yeah, if ischemia is the goal, then most of every bodybuilder trick, from basic high-volume/slow-tempo/peak-contraction ‘pump’ training to rest-pause, drop-sets, and forced-rep methods actually have a place if you’re after maximum size at any cost.

Anything that has the muscle working up to and past the point of fatigue will be adequate to trigger that response.

In the Bigger Picture

Now, this doesn’t really change the game that much – I haven’t changed my thoughts about keeping big lifts and strength-oriented focus as the foundation of your training. Even if ‘strength’ programming had no other effect, the simple fact is that if you can lift more weights, you can do more work with these methods.

On that same note I also haven’t changed my thoughts about keeping ‘bodybuilding’ methods a secondary emphasis, even if you’re after maximum size. The occlusion/ischemia research just slots in nicely with the idea of ‘bodybuilding-specific training’, and lets you body-buffer types feel a little better about what you’re doing. It also gives a nice scientific basis to the Westside idea of combining heavy lifts with very light stuff, like 5×10, or the timed 30-second rest intervals that Louie’s spoken of.

Given that, there’s two options: either add in the ‘pump’ stuff after your big lifts, as bodybuilding-specific assistance work; or combine it with a simple strength template and slot in ‘bodybuilding’ workouts on the non-strength days. The conditioning templates and the ‘beginner and broken’ templates of mine would mesh with this nicely.

It’s functional for bodybuilding, after all. Also it irritates a lot of STRENGTH RAR!!! hardliners, which I enjoy.

Written by Matt


12 thoughts on “Occlusion, Ischemia, and ‘The Pump’”

  1. I've read about this before. And, well, the statistically significant results don't strike me as all that clinically significant. That is, the growth produced from this kind of training isn't so much greater than just training like we've known to. So, why would I want to go through the effort to tie up my arm or legs and go for the pump (and I'm not saying that you're saying to do that)?

    I think going toward the bigger picture, like you said, and integrating it conceptually into your training is the better route, rather than literally trying to replicate this exercise technique.

  2. Time to tape up my entire body and bench press the bar so I can have massively muscular man tits. Fuck yes! ;)

    This is a good write up. Those who've done slow tempo training and seen some sexy results can now know exactly why.

  3. not to quibble, but the strength gains reported in all the studies of kaatsu (and there are several now) show just as impressive a pattern of increase as does size. biopsies show the fiber growth is almost entirely fast twitch.

    it seems hard to acknowledge, but the size gains seem to track strength gains almost one for one.

    this doesn't get over the difficulties of applying kaatsu to the trunk, but there are ways to impeded blood flow (which is what ischemia means) and you have touched on some of them/

    just mixing in really tough, extended isometrics into a regular training set can do this. your other suggestions, also.

  4. I've seen a few big names and gurus essentially say that the same effects of kaatsu training can be gained by doing "pump routines" or hypoxia inducing high rep high tut sets as prescribed in this article, yet have the two ever been compared? In the kaatsu study on rugby players with years of weight training experience these guys increased their CSA by 12% in 8 weeks. I mean that's adding over 1 inch to your thigh if I did my conversion from area to diamter properly. That's a hell of a lot of increased glycogen content, and I doubt if you took a dude with 5 years of weight training experience who was also an anaerobic power athlete, and put him on a pump routine for his quads that he would gain over an inch on his thighs in 8 weeks….am I wrong?

    1. The current thinking is that these protocols aren't just triggering sarcoplasmic hypertrophy. The changes in fiber recruitment are pulling some voodoo which actually does cause myofibrillar protein synthesis.

      As far as comparing the two, I've never seen anything in the same trial. There is however this, from Stu Phillips' team showing a very similar effect with low-load/high-volume exercise:

      Burd NA, West DWD, Staples AW, et al. Low-Load High Volume Resistance Exercise Stimulates Muscle Protein Synthesis More Than High-Load Low Volume Resistance Exercise in Young Men Lucia A, ed. PLoS ONE. 2010;5(8):e12033. Available at: http://dx.plos.org/10.1371/journal.pone.0012033

      Mathias Wernbom has done some additional work in this area and demonstrated similar findings.

      1. Yeah in wernbom's review in 2007 he showed like an average increase of .11% in CSA per day of training the quadriceps…and some of that was wacky, most of it was untrained people combining exercise with electro stim (unless I'm reading that wrong), I think only one study was in recreational lifters….in the 2002 Takarada study on rugby players with 5+ years of lifting they gained at twice that rate….to my knowledge, and I could be wrong, but I haven't found any studies showing a 12% increase in CSA in experienced weight lifters like the takarada study…but maybe I'm wrong…1-1.5inches on your thighs from 8 sets of leg extensions/week when you already have 5+ years under your belt in the gym seems like something above and beyond depletion or pump training could produce

      2. I'm not talking about Wernbom's review. He's published several papers specifically looking at ischemic/occlusion training:
        http://www.ncbi.nlm.nih.gov/pubmed/16686566 http://www.ncbi.nlm.nih.gov/pubmed/18466185 http://www.ncbi.nlm.nih.gov/pubmed/19826283

        For my purposes I'm not concerned with scrutinizing the exact effect size; that's entirely pointless for more reasons than I care to get into. That there's an observable mechanism at play is all that's relevant to me — it works, and I can explain why.

  5. Well sure, it fatigues the slow twitch fibers and preferentially recruits and trains the high threshold fibers, and the same can be done with low load high time under tension work, sure. And there may be more to it than that…but I'm not getting at that angle.
    This is a blog post about bodybuilding and the possible value/relation of occlusion training to typical bro stuff ie squeeze, feel the pump/burn yada yada?
    I would think that muscle size increases might have some value for discussion here. I'm not saying that the training of high threshold motor units can't be reproduced without actual occlusion, I'm saying that the rapid increase in muscle CSA, likely due to increases in glycogen content (which makes sense considering the oxidative fibers are down for the count very early and the greater demand on the anaerobic fibers) possibly can't be reproduced without actual occlusion…and I'm very open to being wrong…I just haven't been able to find anything comparing the two.

    1. It's possible but given the current body of knowledge there's little reason to believe that occlusion by cuff is functionally different from occlusion by contraction. I'd be waiting on something to disprove the similarity, personally.

  6. Well, I may do a little n=1 experiment…I'm about 12 weeks out from my first show of the season….I've done time under tension work, 60-90second low load sets, I've also done significant depletion work, and I've been lifting for 7 years as a competitive natural bodybuilder and powerlifter….I haven't put on 1-1.5 inches on my quads in the last year let alone 8 weeks, no matter the training modality, and no matter what short term carb loading and depletion training approach I've followed.

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