Tennis elbow (lateral epicondylitis) refers to an injuries into the outer elbow tendon that occurs after challenging overuse on the muscles and tendons from the forearm, near the elbow joint.  The pain is worse when arms are straight and also you try and flex your wrists upward (when palms are going through https://www.theorthopaedicandpainpractice.com/how-to-alleviate-tennis-elbow-pain-tips-from-a-medical-expert/