Tennis and golfers elbow are very common injuries and a high percentage of the sufferers of this conditions don't play tennis or golf at all.
Both are tendonitis (inflammation of the tendons) of the elbow and are very related to repetitive movements at work or in daily habits.
Tennis Elbow: Is the term for lateral epicondylitis, or inflammation of the common extensor tendon, located on the outside of the forearm. Muscles that extend the fingers and bend the wrist backward come together at this tendon and attach to the humerus bone in the upper arm. Pain is usually felt at the tendon attachment and along the muscles on the back of the forearm. Over time, micro-tears can develop in the tendon causing weakness in the extensor muscles.
Pain may radiate from the outside of the elbow to your forearm and wrist. It can be a constant ache in the elbow area, or you may only feel it while performing activities that involve reaching, grasping or lifting.
Golfer's Elbow: Is the generic term for medial epicondylitis, or inflammation of the common flexor tendon on the inside of the elbow. Muscles that bend the fingers and wrist forward merge at this tendon and attach to the humerus bone. Pain usually occurs at the tendon and along the muscles on the front of the forearm. Micro-tears in the tendon cause weakness in the flexor muscles, affecting a person's ability to grip.
This injury includes pain on the inside of the elbow when lifting the wrist or hand, pain when twisting the forearm, or when making a fist. The area may be slightly swollen or tender to the touch. If the problem has lasted for a while, additional symptoms can include stiffness in the elbow or weakness in the hands or wrist.