The Trapezius Muscle
The upper traps are muscles most commonly associated with bodybuilders. They are not thought of as a muscle that is important in the golf swing as they aren’t used to for their power. The upper fibres of trapezius muscle run from the spinous process of C7 and the occipital bone and the back of the head to the clavicles (collarbone). The middle fibres run from the spinous process’ of C7, T1, T2 and T3 into the spine of the scapula. The lower portion of this muscle originates from the spinous process’ of T4 – t12 and inserts into the scapula.
Speed or Injury
If any of the fibres are tight then it will have a negative effect on the way you swing a golf club. When you turn you away from from the ball, the left shoulder girdle (in a right-handed golfer) will elevate or the rotation will be limited as a compensation for the tightness in the upper traps. Then on the follow through you may turn your head early, limit your rotation or elevate your shoulder. The middle and lower fibres will limit your shoulder turn and limit protraction of the shoulder.
With the limited rotation, you won’t be able to create the same speed as you would without it as you won’t have as much turn to accelerate through. You will also be limited as your body will have less time to decelerate. This is a great example of how your body will protect itself from an injury. As you move all muscle lengths and tensions are fed back to the central nervous system via muscles spindles and Golgi tendon organs, and they will be telling your body it’s near its end range and needs to slow down in order to not overstretch.
What to do
The first thing to do is make sure that your traps are not only able to move through the required range, but also that they are conditioned to work at this speed. Another thing to do is add some deceleration and negative work into your training whether you have tight traps or not. The process to improve the performance in this area or any other will remain the same. Create the optimum range of motion, increase muscle mass, then make that muscle stronger before making it quicker. Aim for a balance between both right and left as well as with the antagonist.