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An interesting wrinkle in the debate over whether compression garments do anything during exercise to improve performance, from a new Australian study just posted in the Journal of Strength & Conditioning Research. The situation so far:
- Every time you take a step while running, the flexing of your calf muscle operates something called the “calf muscle pump” — basically, your calf literally squeezes the blood vessels in your lower leg, helping to shoot oxygen-depleted blood back toward the heart.
- Graduated compression of the lower leg (i.e. tighter at the ankle, looser at the knee) is thought to enhance the action of this calf muscle pump, by helping it to squeeze harder. This should reduce the load on your heart and speed the circulation of blood through your body, possibly enhancing performance.
- One argument against the idea that compression garments boost performance is that, when you’re running hard, the action of the calf muscle pump is already maxed out, so adding more compression doesn’t help. You can’t squeeze more blood from a stone!
The new study put 25 rubgy players through a form of interval workout: basically 5:00 easy, 5:00 medium, 5:00 hard, 5:00 easy, 5:00 hard, 5:00 easy. They each did the test twice, once in running shorts and once in full-leg graduated compression bottoms. The researchers measured a bunch of variables (heart rate, oxygen consumption, lactate levels, blood pH) during each stage of the workout. There were basically only two elements where the data was significantly different between shorts and tights: in the fourth and sixth intervals (i.e. the easy recovery intervals), heart rate and lactate levels were both significantly lower in compression tights.
On the surface, this fits nicely with the ideas above. The tights don’t help when you’re running fast, since the calf muscle pump is maxed out; but during the easy recovery, the compression does help, resulting in lower lactate and heart rate — and, in theory, better performance on the subsequent hard section.
This is the problem, though: the study didn’t actually measure performance. The pace during each interval was predetermined, so we don’t know whether this difference in physiological parameters actually translates into better real-world performance. That’s a point that was highlighted in another Australian compression study that I blogged about back in August. That study also found physiological “improvements” from compression — but in that case, they also measured performance and found no difference. As the researchers wrote:
However, the magnitude of this improved venous flow through peripheral muscles appears trivial for athletes and coaches, as it did not improve [time-to-exhaustion] performance. This would suggest that any improvement in the clearance of waste products is insufficient to negate the development of fatigue.
Bottom line: I remain skeptical that wearing compression during a run will allow you to run faster. (Note that this is entirely separate from the question of whether wearing compression during and after a run will allow you to avoid or recover more quickly from muscle soreness, a claim that has somewhat better support.) This new study raises the intriguing possibility that compression might boost active recovery during interval workouts — but until it’s directly tested in a performance context, it’s just a hypothesis.
Shouldn’t the weight of the tights, at least below the knee, guarantee the garment reduces performance at worst, making it harder to prove a performance gain?
I wear bike shorts often for running, and while they are probably not as tight as compression shorts the one thing that I can say is that they are warmer than regular shorts or track pants. I used to run in track pants years ago but the cold wind would cause frostbite in certain parts of my lower anatomy *if you know what I mean*. Ever since making the switch I no longer have that problem.
More interesting results would be found when a portable NIRs device is used so you can see if there is a change in blood flow and oxygenation. If they used SEMG they could look at the muscle activity! If they had heomodyanmic device they would know if the heart was working harder with the socks or not. The sock may help to push blood back to the heart, but would the heart not then have to work harder to push the blood back into the legs because of the compression! Lactate is a energy source, so would lower lactate levels be a positive thing? or it might indicate better lactate shuttling to parts in the body where it will be used? Looking at lactate, heart rate and breathing rate alone is not enough. If compression socks work, they work on a mircro scale and and old school ways to look at performance does not work anymore. Make no mistake I am a fan of compression sock for running, as I believe it helps reduce the muscle vibrations, but it is time for research studies to use more modern equipment to do their testing.
@greg: In theory the weight might matter, but in practice I’m not convinced it would make a real difference, since the added weight is so small (and it’s distributed along the length of the leg, as opposed to added weight in a shoe, which causes greater torque because it’s concentrated at the far end of the leg’s “lever arm”).
Think of the reverse case: if someone told me I’d run faster by going sockless since it reduces weight, I’d be skeptical — again because the difference in weight is likely too small to matter.
@Paul: For sure, there are lots of different reasons to wear tights, and comfort is a big one. I’ve definitely got no argument against wearing them!
@Marcel: “More interesting results would be found when a portable NIRs device is used so you can see if there is a change in blood flow and oxygenation…”
In fact, that’s exactly what they did in that study I blogged about in August. And they did indeed see changes in blood flow and oxygenation. But I would argue that the only truly relevant parameter is the most “old school” of them all: actual performance. In the end, who cares about oxygenation, lactate, blood flow, or any other physiological parameter if it doesn’t translate into enhanced performance?
Isnt a side effect of compression the reduced damage due to the shock of the (heel) landing of the foot?
And are the short intervals as described above not to short a time befor the change in energy system from anaerobic to aerobic.
The population is a population with an explosive muscle build up. Wouldnt the muscles from runnens be more “red” type endurance muscle, and will the compression have therefore more effect?
It would be nice to measure actual performance benefits from compression garments but like most of this area of science, unfortunately, it’s impossible to solve for the placebo effect. Compression garments may make you “feel” like running faster or if you believe that they do, they may in fact do so. Pretty impossible to sort that out in a study, so you’ll have to live with biological markers as a substitute (and even then the predisposition factor may play a role).
Agreed that it’s very hard to control for placebo effects. Still, that doesn’t mean we can’t do meaningful performance studies — the study I linked to above (from August) compared different tightnesses of compression. If there’s a physiological effect, then you should see some sort of dose-response effect, or a threshold of compression below which there’s no performance gain. If you get the same effect with fancy “medical grade” graduated compression socks compared to regular non-graduated knee socks (i.e. 1970s NBA socks), then you’re probably just looking at a placebo effect.
Moreover, the placebo effect should make it EASIER to detect performance gains. So at a bare minimum, we should expect that there will be lots of studies showing an “apparent” gain in performance from wearing these socks. Sure, that gain might be placebo. But until we see those performance studies producing consistent results, it’s not even worth starting the debate.
I am 53, working with weights to bulk up and get and stay in shape. If a compression suit pushes water out of the muscles, would it be counter productive for someone trying to bulk up (build muscle mass)? If you don’t know, can you point to some literature that isn’t a sales pitch?
Thank you for the article either way.
@John: It’s not something I’ve seen any research on, but off the top of my head I don’t know of any reason that compression would either help OR hurt attempts to build muscle mass. If you’re trying to bulk up, your focus is on the size of the muscle itself, not how much water it retains.