Tennis elbow is not caused by the size of your racket’s grip. Studies of forearm muscle actions shows little connection between grip size and the development of tennis elbow, also known as tendonitis. Researchers have measured how players’ muscles “fired” during a backhand swing using three different sizes of racket grips. No matter which grip size they used (the optimal grip size and grips ¼” larger and ¼” smaller than optimal), there were no differences in the actions of the muscles studied. A poor swing is one of the biggest risk factors for tendonitis, so use whatever grip size is comfortable for you.