With roller massage legs will appear black blue possible reasons are massage way is not correct, leg fasciitis, blood clotting function abnormalities. 1. Incorrect massage: If the massage is incorrect, such as too much strength when massaging, massage time is too long, it may cause black and blue legs, usually accompanied by pain. 2. Fasciitis of the leg: Fasciitis after pressure may be due to the soft tissue in the adhesion of the loosening of the damage, resulting in subcutaneous bleeding, manifested as black and blue. 3. Abnormal coagulation function: If the coagulation function is abnormal, a very small pressure can lead to subcutaneous bleeding, appearing black and blue. If the massage method is correct, there will still be black and blue, you should go to the hospital in time to find out the cause and targeted treatment.