There are 4 main isometric exercises we do at the elbow. With the elbow bent to 90 degrees, use your other hand to resist the movement of bending the elbow, where you can see and feel your bicep contracting without any movement of the elbow itself. Hold for 15-30s and push as hard as you are able to without any pain. Then do the opposite and resist straightening the elbow to work the tricep. Next resist pronation and supination of the elbow. To do this resist turning the palm of your hand to face down towards the floor, and then finally resist turning the palm up to the ceiling.