The link between the pectoralis minor and distance
The pec minor is a muscle only a few inches long in the chest, going from the 3rd, 4th and 5th rib into the coracoid process of the scapula. Its action brings the shoulder girdle forward (protraction) and downwards (depression).
Seemingly a small muscle but a very significant one. If tight or in spasm, it will bring the shoulder girdle forwards and down, this will tension the muscles that act in the opposite direction. These include trapezius, rhomboids and latissimus dorsi and through a series of muscles be linked to tight hamstrings. In can also cause thoracic outlet syndrome, which is where the nerves and blood vessels between your collarbone first rib are compressed causing dysfunction.
But most relevant for golfers is the effect it has on your rotation. You can test this yourself. If you sit down on a chair (this isolates the rotation to come mainly from the spine) slump your shoulders forward and down and see how far you can rotate, then pull your shoulders back into a neutral position and see how much further you can rotate. It should be a noticeable amount. Those extra degrees at arm’s length can give you an extra couple of feet for your hands to accelerate in the downswing. Added to that you will also reduce the load on your spine to help with longevity in playing years It will also reduce the occurrence of injury.
This is a muscle that can easily be ‘fixed’ if it isn’t in spasm simply by stretching it. However, if it does not release properly or goes back into its tight position then you will need to see a specialist as the muscle may have length/tensions issues with its antagonist or it may be in spasm for a reason.