How much compression do socks need?

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Over the past few years, there’s been a ton of research into the effects of various types of compression gear, with conflicting results. Some studies show improved performance, others don’t; some studies show changes in physiological markers, others don’t. One of the big problems is fit: no one really know exactly how tight the garments should be.

A study from researchers at Massey University in New Zealand, which appeared online in the Journal of Strength and Conditioning Research last week, attempted to answer this question. They had 12 well-trained runners complete four 10K time trials on the track wearing four different socks: a non-compressing control, one low compression (12-15 mm Hg), one medium compression (18-21 mm Hg) and one high compression (23-32 mm Hg). All the socks had graduated compression, with maximum compression at the ankle tapering to no compression at the knee.

The results: no significant difference in 10K time, pre- or post-run lactate, heart rate, or several other measures. Now, I have my doubts about the statistical power and repeatability of a 12-person study with four 10Ks over the course of eight weeks, but take it for what it’s worth.

There was an interesting twist, though, represented in the following graph:

We’re looking at the change in “countermovement jump height” from before the race to after the race. The low compression sock shows a significant improvement compared to the control, and the medium sock has an even bigger improvement, while the tightest sock is roughly the same as the control. This test is basically a measurement of leg power, so the researchers speculate that it’s possible that the subjects might be able to produce a faster finishing sprint in the low and medium socks, though it’s not something they measured. I’m fairly skeptical — I never really had the sense that explosive leg power was the limiting factor in the final stretch of a 10K race. But who knows?

In the end, the study is a perfect microcosm of the greater body of research in this area: it shows that something happens when you put properly fitting socks on, but we still don’t know exactly what and we certainly don’t have evidence that it actually makes you faster. But in other ways, the study is a big step forward, in that it makes a serious attempt to determine what a “proper” fit is — at this point, 18-21 mm Hg is looking pretty good. More studies like this will be needed. And one addition that I would really like to see is a placebo compression sock — perhaps something with non-graduated compression that subjects can’t necessarily distinguish from the “real” socks.