The use of compression stockings during a marathon competition to reduce exercise-induced muscle damage: are they really useful?
By Francisco et al., JOSPT, ahead of print
This article is very interesting. As this is one of the questions that I frequently get asked about when giving presentations on running. Do compression stockings improve performance?
Let’s quickly review the thought process behind why compression stockings (socks) are thought to work. Graduated compression socks surround the calf muscles and increase the calf muscle pump and improve venous blood return. Improved venous return brings more blood back to the heart allowing for increased cardiac output. Having an increased cardiac output would allow athletes/ runners to perform at higher intensities. Basically, compression socks stop blood from pooling in the calf and feet and forcing the blood to return to heart to be pumped out again full of oxygen to be delivered to the muscles.
This has already been shown not to happen in a shorter race than a marathon. The previous study was done in 10 km race.
So what happens in a marathon? Let’s find out…
This article had 34 people participate in the study, 17 people ran a marathon with the same brand of compression socks and 17 people ran the same marathon with the same low cut athletic socks. Before the athletes ran the marathon, 2013 Rock and Roll Marathon in Madrid, the researchers measured a bunch of things: blood glucose, blood lactate, blood sodium, potassium, chloride and calcium concentrations. In addition, myoglobin, creatine kinase and lactate dehydrogenase were used as indicators of muscle damage. Also were measured lower leg volume, jump height, mean leg muscle power and drop of center of gravity during the landing phase.
Now a little about the 2 groups of 17. This study matched the people running with compression socks to people running in regular athletic socks. This is important because they do not want to only give compression socks to faster marathon runners. Then they could, incorrectly, state that the runners with the compression socks were significantly faster than people that ran in regular socks. The participants were matched with age, body weight, years of running experience, completed marathons, best marathon time, average training distance per week and training sessions per week. I personally thought that was pretty good.
So what did they find? Not a whole bunch. The only difference between the runners with compression socks vs regular socks was that the day after the marathon, the runners that wore the compression socks reported less muscle soreness. But by the second days, 48 hours after the marathon, there was no difference. The day after the marathon, runners with compression socks reported their pain on average as 5/10. The runners in regular socks reported their pain on average as 6/10. That was the only difference but it was enough to cause some statistic significance.
The researchers could not measure a difference in the total race time, running pace, post race blood values of myoglobin, creatine kinase and lactate dehydrogenase, between the compression vs. conventional sock group. The leg volume changes and the decrease in muscle performance were also similar between the groups.
Their conculsion was this:
In summary, the group of runners wearing compression stockings during a marathon race did not improve marathon race time while they presented similar reductions in muscle function to a group of runners that wore conventional socks. Furthermore, the use of compression garments did not modify perceived exertion or the post-race concentrations of blood markers of muscle damage.
I agree with the authors. Just a couple of comments. I like that they used everyday marathoners, i.e, the average race time for the compression sock group was 214 minutes (3:34 marathon) and the control group was 210 minutes (3:30 marathon).
Last point, I promise. In the study, they did a power calculation, that is approximately how many people they need in each group to make the results, worthwhile. The power calculation for this study was 19. They only had 17 runners. This could mean that there could be a difference between runners wearing compression socks and normal socks. Maybe there were not enough participants to separate the difference between both sides.