Tennis elbow is mostly caused by overusing your forearm due to a repetitive or strenuous activity.
It can also sometimes occur after banging or knocking your elbow.
If the muscles in your forearm are strained, tiny tears and inflammation can develop near the bony lump (lateral epicondyle) on the outside of your elbow.
You may get tennis elbow if your forearm muscles are not used to doing a certain activity, such as gardening or decorating. However, even if you use your forearm muscles frequently, it can still happen.
You can develop tennis elbow by doing any form of activity that involves repeatedly twisting your wrist and bending your elbow or using your forearm muscles. Examples include:
Playing racquet sports increases your risk of developing tennis elbow, particularly if you play for the first time in a long time. However, despite its name, only 5 out of 100 people actually get tennis elbow from playing racquet sports.