Kaatsu: a shortcut to more muscle, but maybe not better health
Last week, Anne asked the backchannel about a workout trend she had come across called Kaatsu, sending along this link from Military Times and this one from Wikipedia. Her question was basically “does this set off any of your bullshit detectors” and as I am in the weird half-way point between fitness instructor and biologist, I took it up.
What is this, even?
From what I can tell, the method is relatively simple — you strap fancy blood pressure cuffs to your upper arms and legs, and do what would be a short, low-stress workout. The tension of the blood pressure cuffs causes the blood to pool in your extremities, which in turn means that they can’t properly oxygenate, and in the absence of more oxygen more lactic acid is produced. Lactate is a signal to the body to rebuild the muscles, so you get a spike in new growth of those muscles without all the pesky “working out” to cause it.
It has a couple caveats — they use blood pressure cuffs and not, say, tourniquets because the tightness has to be pretty carefully monitored in order for this to work well and not just cause injury. After all, working your muscles in the absence of oxygen is generally speaking not the best idea. (Just saying.) And the whole kit, plus training in how to use it, would run you about $2000. So for now it seems like the kind of thing that specialized high-performance athletes, and military trainers would be interested in. Not really for laypeople.
In the backchannel, Ashley brought up a connection to steroids. It’s worth noting that this is a bit different from steroids because steroids generally act by increasing the response to muscle damage when that damage occurs, this sends a false signal to the body that muscle damage has happened in the first place. The best analogy I can come up with is that steroids are like training more structural engineers so you can build better bridges. It’ll work as long as there’s reason to build bridges. Kaatsu claims to be different — it fakes a bridge collapse which actually gets legislators to temporarily reinvest in infrastructure, to build a ton more bridges right away. The point? It doesn’t matter how many engineers (in the analogy, how much testosterone) you have if they’re not building bridges.
Is it really the next big workout thing?
In general I find it plausible that this would be a way to very quickly and relatively easily build a huge amount of lean muscle mass. That’s for several reasons — mostly the concordance of several unrelated experts quoted in the article. The fact that they have a basically plausible mechanism doesn’t hurt, but it honestly doesn’t help much (lots of things are unsupported by reality and have basically plausible mechanisms). So I can act on the premise that yes, this would be a way to quickly build muscle.
But would I use it? Probably not. Would I recommend it to all my friends? Probably not.
I think most people aren’t in the gym JUST to build large amounts of lean muscle mass. It wouldn’t do anything to burn fat, it wouldn’t do anything to increase cardiovascular fitness. It JUST builds muscle. So if you’re already in good shape, and want to push it to the next level of lifting-things (i.e. military applications, high-performance athletes) this is great. You can lift a lot more weight quickly. If you’re trying to shed pounds, or if you’re trying to build endurance, this won’t do much if anything.
And moreover, I think that there’s a bit of a problem in how we think about health if “lifting more weight” is equated with health in a 1:1 manner. It’s a similar, if not as common, misapprehension as “healthy == skinny”. Or any other oversimplification of health.
Relevant to Kaatsu specifically, strength is a part of fitness but it’s only part — flexibility, tone, endurance all contribute to the bigger picture and if you’re not working on those then you’re missing out on a lot. The rest of the workout, and an active lifestyle, address all of these things. It seems like Kaatsu focuses just on tricking out the body to make muscle, which can be useful if you need to build a lot of muscle in a short time and are already doing (or don’t care about) the others, but it’s not going to do the rest. So that’s one caveat — this is part of, not all of, a full fitness regime (just like strength training generally).
The other big gaping hole here is that while this approach would work for extremities it would be impossible to jumpstart core strength — you can trap blood in arms and legs but not really in your abs or core.
What do they need all that muscle for?
I think in reality, the best way to judge “are you in shape” is “can you physically do the things you want to in life?” It cuts through all the externalities of the fitness industry (BMI, body fat percentage, dead lift) and turns it into a practical consideration: are you living the life you want?
It also makes fitness much more holistic than just a weight (whether that weight be how much you can lift or how much it takes to lift you). It makes fitness flexible — my fitness goals are probably not your fitness goals.
Here’s something I’ve run into a lot in circus arts — a muscled out guy will sign up for my class. He thinks that everything should be easy since he’s already so strong. But in the end, he struggles because he doesn’t have the range of movement, or the endurance, or the coordination. He can lift a lot of weight, but if he can’t put his arms above his head there’s a lot he just can’t do. He actually needs to lose some of that bulky muscle, probably, to get what he wants out of his body.
The powerhouses in my particular area of athletic expertise are usually people like gymnasts and dancers — generally not hulked out but with a low body fat percentage, great range of motion and the strength, coordination, and endurance to control it over the course of hours of training. I’ve even had coaches remind me that conditioning just for the sake of conditioning — as in, going to a conditioning class — is not useful when you’re not SERIOUSLY hurting for strength. The best way to stay in good enough shape to do a certain thing is to do that certain thing, and the best way to get in good enough shape to do it easily is to do it three times every day.
And muscle, while it does make you stronger, also makes you heavier, so if you’re thinking about just increasing mobility then there’s definitely a sweet spot beyond which more muscle doesn’t help.
As with every fitness regimen, I feel like the VERY first question you have to ask is really “what are your goals” — if you want to lift heavier things quickly, this might be a great way to do that. If your goals aren’t just “bigger muscles in my arms and legs” well, then… you’ll need something else in addition to this.