Compression Socks

Compression socks are very popular amongst athletes, particularly triathletes and endurance runners.

For more information about triathlon gear visit our Triathlon Gear main page


  • What are they?
  • Do they work?
  • What do they actually do?
  • Should you be using them, and if so, how?

What Are Compression Socks?

These socks create compressive pressure around the muscles, bones and connective tissue of the lower limb.

Traditionally most compression running socks provide compression which is highest around the ankle and then reduces gradually up to the top of the sock just below the knee.

Compression socks

However now some companies are producing socks where the compression is progressive up the leg – ie lower compression around the ankle and higher around the belly of the calf muscles.

The theory here is that pressure around the ankle is unlikely to offer much compression to the veins as the bony structures of your ankle inhibit this. In addition higher pressure on the calf muscles is needed to have any effect on venous blood flow.

Levels Of Compression

There are different grades of compression, and most commercially available sports socks are fairly low level (around 15 - 20mmhg).

Level of Compression Use
8-15 mmhg light compression Travelling
15-20 mmhg therapeutic compression Sport
20-30 mmhg medical grade Recovery from sport/medical use
30-40 mmhg medical grade Medical use
40-50 mmhg medical grade Severe medical cases only

Do Compression Socks Work, And If So How?

Socks which provide compression have been used for a long time in the medical setting, to treat deep vein thrombosis and venous problems. They have been proven to improve blood flow in the veins of the calves and reduce the accumulation of fluid beneath the skin.

During exercise the calf muscles contract and relax repeatedly. When the muscles contract, the pressure exerted on the veins pushes the blood through the one-way valves of the veins, enhancing the return of blood flow to the heart. Socks which provide compression are thought to enhance this pumping action.

It has been suggested that this enhanced blood flow would improve oxygenation of the muscles and improve the removal of waste products.

In the sporting world there is conflicting evidence of the usefulness of compression socks.

Research studies have found positive effects of compression running socks such as:

  • Reduction in muscle oscillation, optimising muscle alignment and reducing muscle microtrauma
  • Improved muscular resistance to fatigue
  • Lower blood lactate levels
  • Improved running economy
  • Enhanced muscle oxygenation
  • Reduction in delayed onset muscle soreness.

Equally however there have been studies that have found no beneficial effects of using compression socks.

There does however appear to be a trend for those studies who haven’t found effects to have used lower grade compression, or their subjects have not done as challenging protocols as other studies, or they’ve run on a treadmill where the ground reaction forces (and therefore likelihood of muscle damage) are lower than road running.

What is clear is that no negative impact has been seen in any of these studies, even when used in the heat. Therefore wearing compression socks might help your performance but even if they don’t, they are unlikely to do any harm.

How To Use Compression Socks

In theory, the key areas where wearing medical grade compression socks can help in sport are:

  • Performance
  • Recovery
  • Injury rehabilitation
  • During travelling

If you do decide to use compression socks, here is some information to help you get the most out of them.

Choosing Your Socks

The level of compression will influence the effectiveness of the socks. Some manufacturers sell them by foot size. This is not going to be ideal, as two people with the same sized feet could have very differently sized calves, and therefore will get a different compression level from the same sized socks.

Some manufacturers allow you to select your sock size by usingmeasurements of your calf and ankle. This is a much better option.

Nowadays some companies are producing custom-made compression garments, and these are the best option, as they will be made to provide exactly the stated compression level no matter your leg size.

There are two options of compression grading. Most companies provide socks where the compression degrades (ie gets lower the higher up the sock), but now you can buy ones that have progressive compression, with higher compression around the calf muscle rather than around the ankle.

There has been limited research comparing the two types of sock, so it really is a case of trying a pair and deciding if they work for you.

When you put your socks on, ensure the top of the sock is just below your knee. If the sock appears too long, do not fold it over at the top, this will change the compression level. Instead, position the top of the sock just below your knee, then manipulate the sock until the material is smoothed out evenly the length of your calf.

When To Wear Compression Socks

In general it appears that the ideal compression for socks used during activity is 20mmhg, with a slightly higher compression level (25mmhg) being better for use during recovery from exercise.

compression calf guard

Racing: An important point to note if you are a fan of compression socks, is that they are banned in triathlon races by the ITU.

Any form of sock is classed as ‘illegal equipment’ for the swim. So if you do want to use compression for your lower legs you will need to look at the footless,‘calf guard’ options.

Training: It would appear that beneficial effects of socks which provide compression would be most likely to be seen if you wear them for particularly long or hard running sessions. If you are returning from an injury to your calves, then the added support and compression the socks provide could be beneficial.

Recovery: Socks which provide compression can reduce muscle soreness, so put them on after a training session for 2 – 3 hours to enhance your recovery.

Remember there are many other techniques you can use to enhance recovery, you can find out more about them here.

Injury: Most people will be familiar with to ‘RICE’ guide to injuries – rest, ice, compression, elevation. Compression through the use of these socks can be useful if you have sprained or injured your ankle, damaged your calf muscles or have shin splints/compartment syndrome.

Travel: If you are going to be immobile for a long time whilst travelling, then these socks can be helpful at improving blood flow in the calves and reducing the swelling associated with long periods of inactivity. Don’t rely solely on your socks though, move around as much as you can (even clenching and relaxing your calf muscles whilst seated or circling your ankles and so on), and stay hydrated.

Summary Of Key Things To Consider When Choosing & Using Compression Socks

  • Get the right fit and right compression level.
  • Put them on properly – no folding over the top.
  • Wear them in races (but no foot for a triathlon) and for your longest/hardest running sessions.
  • Wear them in recovery, after training.
  • Use when travelling to a race.

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