According to the New York University Langone Medical Center, a muscle strain, also known as a pulled muscle, typically produces pain and soreness when moved. Sometimes twitching occurs in the muscles or a tender, hard knot appears in the area.
NYULMC states that a black and blue mark might be present in a second degree strain along with stiffness and weakness. Third degree strains are those where the muscle has torn, and in such cases, it is sometimes possible to feel the muscle fibers that have bunched up. A more prominent bruising might be present, caused by bleeding within the muscle.
A muscle strain that is mild to moderate may take weeks to heal, but a severe muscle strain can last for months. Often, mild-to-moderate muscle strains require physical therapy, and in severe cases, surgery may be required to repair the affected muscle.