Tennis elbow is a soreness on the outside part of the upper arm, near the elbow. Basically, if you do a lot of repetitive twisting of your wrist — hitting a backhand, for example — small tears develop in the tendon that attaches the muscles in your forearm to the bone on the outside of your elbow. Though it's often a problem for people who play tennis or other racquet sports, you actually can develop the condition from any other activity that involves the same twisting motion over and over, whether it's painting, plumbing, cooking, or using a computer keyboard or mouse [source: MedlinePlus].
If you've ever had to endure this malady, you know that getting rid of it isn't easy. But a study published in 2010 in the Canadian Medical Association Journal suggests that Botox injections might help.
In the study, researchers at a university hospital in Tehran, Iran gave injections to 48 tennis players who hadn't been helped by previous treatments. The shots paralyzed the extensor muscles of the fingers, relieving tension. The result was significant reductions in pain while the athletes were at rest.
The treatment, however, did have a significant drawback, in that it weakened the patients' ability to extend their third and fourth fingers, though that side effect faded after four months [source: Loriggio].