Quick recap on the anatomy and mechanism of a pulled hamstring
The main fleshy part of the hamstring muscles consists of thousands of muscle cells that are grouped together in bundles. These bundles are held together by a thin layer of fascia (that white sinewy stuff in meat). One muscle contains lots and lots of these bundles. The muscle itself is also covered by a layer of fascia. The fascial layer is penetrated by blood vessels. The blood vessels divide until they are tiny enough to supply oxygen and nutrients to every cell.
Why do some hamstring strains bruise and others don't
A bruise is just an accumulation of dead or old blood under the skin. It forms whenever you injure a blood vessel but you’ll only see it if the blood can get close to the skin. This can often take a few days. For a bruise to disappear, the body has to absorb the dead blood and remove it via your lymph system.
When you strain your hamstring, you tear a few of the muscle cells and usually also some of the blood vessels. Whether you see a bruise or not will depend on:
Reasons for bruising
The size of the blood vessels
If the blood vessels you injure are tiny, there will be very little bleeding and it will stop quickly so you will likely not see much bruising. If you tear a bigger blood vessel, it will likely bleed more and result in a larger bruise.
The fascia stealth
Sometimes a person may tear a significant blood vessel but all the bleeding is contained in the facia sheath that surrounds the muscle. In that case, the blood may not be able to move to the skin and will remain at that deeper level until it is absorbed. This is why you may not see a bruise despite having a very painful hamstring strain.
What you did immediately post injury also counts
The amount of bleeding is also determined by what you do in the first 24 hours after injury. If you stop your activity immediately and follow the PRICE regime, you will limit the bleeding and have less bruising. If, however, you continue your activity you will likely bruise more. Certain substances like alcohol and aspirin can also thin your blood and cause more bleeding.
Why bruising can occur lower down the leg
Are you wondering why your pulled hamstring bruise is so low down – around your knee or even in your calf? This is quite common simply because gravity has pulled the old blood towards the floor.
How to get rid of the bruise from a pulled hamstring
Most bruises will disappear within 14 days without you doing anything to help it along. As it resolves, it usually turns from deep purple to green and finally yellow. Getting rid of the bruise won’t make your injury heal more quickly so don’t worry about it too much.
The research has so far not really found anything that is super effective. There is some evidence that applying a 20% Arnica solution may be beneficial. Solutions of 10% or less don’t seem to work.
Kinesiology tape is claimed to improve lymph drainage, which in turn can improve how quickly your body can get rid of waste products (like dead blood). I’m not aware of any research studies that prove this specifically but there is some very convincing real-life evidence that suggests that it may be worth a try. If you google “k tape bruising”, you’ll see plenty more pictures like this one.
Some people also use contrast therapy, where they alternate between applying heat and cold to the area, in order to increase the blood flow with the aim to remove the dead blood more quickly. Once again, there’s really not any research to support or refute this method. However, please DON’T use contrast therapy in the first 72 hours after pulling your hamstring as you can actually cause more bleeding and bruising by doing it before your injury has had time to settle.