Compression socks (clothing)
I frequently get asked do compression socks (clothing) actually work,
what are the benefits, what do they do? So, I wanted to provide you with some quick answers.
A research paper published this year accumulated and analyzed all previous studies about the effects of compression clothing on running performance and recovery and it concluded that “that by wearing compression clothing, runners may improve variables related to endurance performance (i.e., time to exhaustion) slightly, due to improvements in running economy, biomechanical variables, perception, and muscle temperature. They should also benefit from reduced muscle pain, damage, and inflammation.” 
So what does this conclusion actually mean to you and I?
First if all, how does compression clothing actually works?
Originally compression wear was developed for swelling disorders in the limbs, and this led on to compression socks to treat vascular disorders, such as varicose veins, and to help to prevent blood clots in bed-ridden patients after surgery. These are typically knee high socks with the compression highest at the ankle and tapering off towards the knee.
The socks work by creating positive pressure on the one-way valves in the veins and the difference in pressure between the ankle and the knee encourages blood to flow back to the heart, against the forces of gravity (which is why it is advised for frequent flyers to minimize deep vein thrombosis too).
So the improved circulation and blood flow are the major selling points when you look at buying any compression clothing or socks.
What does this mean for you the runner (cyclist)? Do compression socks/sleeves actually work? Below are some answers based on compression socks.
For muscles soreness (DOMS (delayed onset muscle soreness) - YES, there are studies that conclude positively for a reduction in muscles soreness and pain post intense exercise
Lowers heart rate (which is good for sustaining a higher level of effort, good for endurance) – YES - this has been proven in running to exhaustion over a 5km distance , but in this particular study the results were minimal so it still remains inconclusive.
For endurance performance - YES – studies have concluded better endurance,
specifically noting better mechanical performance (muscles less fatigued) over a distance of 10K . Compression helps to stabilize the muscles and decrease the amount of muscular vibration.
For improved recovery – YES – lactic acid levels (the by product of anaerobic metabolism) have been found to be notably lower immediately post exercise aiding muscle recovery 
Comfort- YES - close to the body to wick away sweat and prevent rashes
Temperature – YES – keeping the muscles warmer, means more blood flow and more oxygen is readily released, muscles contract and relax and nerve transmission is better.
So these are ALL the benefits. However, it does appear from the results of all the studies that they did not provide overly conclusive results about these benefits, but nonetheless positive marginal ones.
So are compression socks, sleeves, shorts worth the money?
It seems that they are not a game-changer. The most conclusive evidence suggests they are best used to prevent excessive soreness and muscle damage from hard training sessions and there is some evidence that over longer distances they could improve your performance. My husband is a fan of the socks and we have of course discussed the placebo effect, if you like wearing them and feel they are helping your performance and recovery, then why not, there is no harm in trying and wearing them!
Are compression socks good for shin splints, calf cramps, strains and Achilles tendonitis?
YES, for all of the reasons noted above, but they are not going to cure any of the above injuries, you should still follow initial PRICE (Protect, Rest, Ice, Compression, Elevate) principals and get an injury assessed for proper recovery and the cause to be addressed. Note, for recovery from an injury it is better to wear a sock rather than a sleeve so that the foot doesn’t get swollen, as it can’t get past the compression at the ankle!
An important point when looking to buy compression socks is they should be rated and sold in millimeters of mercury or mmHg at the ankle and calf. So a sock labeled 15-20 mmHg is 20 mmHg at the ankle and 15 at the calf, and this is a recommend rating for sporting use.
NB. The above article is meant to give you an overview of the benefits of compression socks and sleeves in a running (sporting) context. This is my summary of a number of articles and papers I have read. I hope this helps! Any queries let me know