Several converging muscles and the chest wall form the armpit, or axilla. Major muscles forming the axilla include pectoralis major in the front; latissimus dorsi, subscapularis and teres major in the back; and serratus anterior overlying the chest wall. A muscle strain injury can occur in any of the muscles forming the armpit. Common movements in weightlifting, tennis, baseball, basketball and football, for example, employ strenuous use of these muscles. Pulled muscle damage can happen all at once or develop gradually from long-term repetitive actions.
Signs and Symptoms
A pulled muscle, or strain, describes minor to severe tearing of muscle or associated tendon fibers. Pain is the most common symptom of an armpit muscle strain, which is often aggravated by specific arm and shoulder movements. Swelling may also be present during the first day or two with a severe strain. A pulled muscle may result in weakness, stiffness or a burning sensation in the armpit muscles. Compensation for the reduced strength of the injured muscle may cause soreness in nearby areas from overuse of other muscle groups.
The location of the pain and movements or activities that trigger or worsen the pain point to the diagnosis of an armpit muscle pull. The healthcare provider will examine the area for deformities, strength, and range of motion of the upper arm and shoulder. X-rays or other imaging tests may be ordered in the case of an acute, traumatic injury or if the diagnosis is uncertain.
Treatment and Recovery
Application of cold packs to the area for the first 24 to 48 hours is often recommended to control pain and swelling. An anti-inflammatory medicine, such as ibuprofen (Advil, Motrin), naproxen (Aleve) or aspirin, may also be helpful during this early time period after an acute injury. Resting the injured muscle by avoiding activities that stress the area is important to allow healing of the torn muscle or tendon fibers. Depending on the muscle involved and the severity of the strain, use of a sling for a short period may be recommended. Minor strains typically heal in 3 to 6 weeks. Chronic or more severe injuries may require months of physical therapy for full rehabilitation. A complete muscle tear might require surgical repair.
Placing excessive demands on muscles that converge in the armpit and improper training technique raise the risk for painful muscle strains. Gradually building up your fitness level can reduce the risk for muscle strain. Coaching or advice from a professional trainer or physical therapist can be useful for ensuring balanced muscle training and proper technique. Alternating light and intense workouts also helps avoid overuse injuries.
When To Seek Medical Care
People often put off seeing their healthcare provider for a pulled muscle. This can be a mistake because a muscle strain that isn't treated properly can lead to repeat or chronic injury. See your healthcare provider for any armpit pain that fails to improve with a few days with rest. Seek medical care right away if your injury occurs suddenly -- especially if you feel a sharp, tearing pain, hear a pop, cannot move your upper arm normally, or notice a lump in your armpit.
Reviewed by: Tina M. St. John, M.D.