I got a patient who was a construction worker, a few days ago. He was suffering from right-sided Tennis elbow, and he had never played tennis in his lifetime. It's a misnomer named disease in the medical field. In fact, a particular type of pain in the elbow joint is known as Tennis elbow.
_The legendary Roger Federer; We don't know if he has ever suffered from tennis elbow or not_
The patient had pain in the outer aspect of his right elbow joint for several weeks. The pain happened to radiate to his forearm. He was a construction worker as I mentioned above and a few days earlier he did "wall plaster" continuously for several hours; afterwards, he started having the pain which increased gradually.
If a person moves his upper limb, repeatedly in the same way, for long hours, as seen in the tennis players, he may feel pain in his elbow. That's the Tennis elbow.
Rest and simple painkillers are enough in most of the cases of tennis elbow. It usually resolves over several months. In some complicated cases, needs steroid injection at the site of maximum pain.
Image source: Both of the gif pictures here are from https://tenor.com/