Tennis elbow (lateral epicondylitis) refers to an injuries towards the outer elbow tendon that happens right after strenuous overuse with the muscles and tendons from the forearm, close to the elbow joint.  The pain is worse when arms are straight so you try to flex your wrists upward (even though palms are https://www.theorthopaedicandpainpractice.com/how-to-alleviate-tennis-elbow-pain-tips-from-a-medical-expert/