There are three main joints that are stressed when playing golf. These include the wrist, the elbow, and the shoulder. Although both the knees, as well as the hip, are often moved (see pictures 5-8), these joints are not quite as important and no injuries usually occur in these areas. Power is definitely gained from their movement though. Another area that is involved with movement is the trunk. Though technically not a joint, it is extremely important in the golf swing, and is an area where injuries do occur. The following descriptions are for a left handed golfer. Although more rare, I am one of them, so it’s easier for me to explain
Wrist The wrist joint is a condyloid articulation, and more generally a synovial joint, and is very important in the game of golf. This means it is bathed in synovial fluid, allowing a great deal of mobility. At the beginning of the stroke, the wrists are pointed downwards slightly. They will be flexed upwards by the top of the backstroke, bent down again at contact, then up again at the top of the follow-through.
Elbow The elbow is a hinge joint, so although it cannot move side to side, its stability is key to golf. The left elbow will be bent throughout the stroke. It will conform to the movements of the right elbow, and may be slightly more bent or straighter at different times. The right elbow, however, will be kept straight throughout the golf wing, until the follow-through, when it will bend as the club turns around the body.
Shoulder The shoulder, or glenohumeral joint, is a synovial joint, and more specifically a ball and socket joint. Both shoulders twist to left and up during the backswing, then right and down during the downswing. The shoulders finish off the follow-through by turning up and to the right.
Muscles and Bones
There are about 22 muscles that are used to power the golf’s downswing. The descriptions are again for a golfer that shoots left.
Hip The gluteus maximus, gluteus medius, quadratus femoris, pyriformis, superior gemellus, inferior gemellus, obturator internus, obturator externus, and gluteus minimus are all involved in the lateral rotation of the hip. This rotation is very important to generate power, as it shifts the golfer’s body weight towards the target. Some of the bones that move in this area include both of the femurs, tibias and fibulas, which both internally and externally rotate; and the pelvic bones, which pull the leg bones into their movements.
Spine There are three rotators of the spine, the external obliques, the multifidus, and the rotators. The external obliques are the most important. During the backswing, the right obliques flex (concentric), while the left obliques extends. This happens because the torso twists to the left. During the downswing, the opposite takes place. This happens because the torso twists to the right. This motion is carried through the follow-through. The bones in this area that are twisted are the vertebrae, from the lumbar all the way up to the cervical.
Arms The six main muscles used to move the arms are pectoralis major, posterior deltoid, teres major, latissimus dorsi, triceps brachii, and anconeus. The pecs allow for interior rotation, both in the backswing (right pec) and downswing (left pec). The posterior deltoid is involved in shoulder abduction, the left for the backswing and the right for the follow-through.
Teres major allows for the shoulders to internally rotate, the right muscle for the backswing, and the left muscle for the downswing. The lats internally rotate the arm, the right shoulder on the backswing and the left shoulder on the downswing and follow-through. Both the triceps brachii and the anconeus extend the forearms at the point of contact with the ball. The bones in this area that are most important include the humerus, the radius, the ulna, and the scapula. The scapula is very important, protracting both in the backswing (right side) and the follow-through (left side). The bones of the arm are what guide the club, so it is necessary to be aware of their movement.
Wrists There are four tiny muscles of the wrist that help in a successful swing. The flexors in the left wrist are active by the top of the backswing, with the extensors in the right wrist being active by the same point in time. The carpals, metacarpals, and phalanges are extremely necessary to maintain a proper grip of the golf club throughout the swing.