Trigger points are the clinical name for contracted muscle knots. These knots are the result of an overload stress placed on the muscle tissue. This overload can be from both acute or chronic stresses. When this happens some of the muscle fibers get locked together in a maximally contracted spasm that self perpetuates. These trigger points then cause symptoms such as pain, referred pain, stiffness, and weakness. They are one of the most common source of pain in the human body, and can even mimick symptoms of other conditions. Trigger points don’t go away on their own, they also can’t be treated with stretching, rest or rehabilitation exercises. A direct intervention targeted directly at the point itself such as trigger point massage therapy is the only way to release a trigger point.
With a whiplash injury the muscles of the neck get overloaded and strained. When this happens trigger points can form in any or all of these muscles. Trigger points in the neck muscles will refer pain into the head and face causing headaches and migraines. These points won’t release with rest, stretching, or rehab exercise. They require a manual technique like trigger point massage for them to resolve.
From Discover on Google https://www.insider.com/signs-your-workout-is-hurting-you-2018-5
The Subclavius muscle is a small muscle on the underside of the clavicle. It originates on the first rib and it’s cartilage, and inserts on the inferior clavicle. It’s main function is to assist in protraction of the shoulder. This muscle is often shortened and tight from poor rounded shoulder posture. When trigger points form in this muscle they can refer pain into the anterior shoulder and down the radial part of the arm. Pain can also be referred into the thumb and first two fingers.