Why do the shoulder muscles ache after an injury?
Fiber damage or tissue damage of the muscle occurs when the tissues tear. This can either be from the muscle or the tendon attaching the muscle to the bone. The tearing of the muscle fiber can also injure the blood vessels which causes bleeding in the area, or bruising, and pain caused by irritation of the nerve endings in the area.
Most muscle strains happen during high-speed and high load activities like sprinting or running. The most relevant muscle strains injuries can be in your hamstrings (hamstring strain), quadriceps (quadriceps strain), calf (calf muscle tear), and groin strain (adductor strain). These are the most common, but this can happen to almost all muscles.
Strain from sustained positions can also cause a muscle strain. Long periods of sitting in a posture can overstretch muscles in the back and neck which can then be strained. Back, shoulder and neck muscle strains are very commonly related to postural strain. Text neck has become a common condition due to postural fatigue while overusing your phone.
Muscle pain can also be caused from micro-tears in the muscles related to exercise. DOMS or delayed onset muscle soreness describes the pain or stiffness after vigorous exercise which can last anywhere from 24-72 hours depending on the amount of damage.