The latissimus dorsi, or “lats,” is the broadest muscle in the human body, spanning the middle and lower back and extending to the upper arm. While primarily known for its role in shoulder and arm movement, the lats also assist in breathing, particularly during deep inhalation or forceful exhalation. When pain in this muscle group is triggered by the simple act of breathing, it suggests an issue involving structures that move with the rib cage. The pain usually stems from localized muscle trauma or, less commonly, from inflammation or pathology in underlying internal organs.
Musculoskeletal Origins of Lat Pain
The most frequent cause of pain in the lats that worsens with breathing is a muscular strain or spasm. Activities involving repetitive or forceful overhead movements, such as rowing, swimming, or weightlifting, can overstretch or tear the latissimus dorsi fibers. When the lung expands during a deep breath, the rib cage moves, which pulls on the injured muscle and causes a sharp increase in pain.
A strain in the intercostal muscles, the small muscles running between the ribs, can often be mistaken for lat pain. These muscles are responsible for expanding and contracting the chest wall, and a strain causes significant pain with every breath, cough, or sneeze. Because the lats cover a wide area of the thoracic wall, the localized, sharp pain from an intercostal strain may be broadly perceived across the back.
Inflammation of the cartilage connecting the ribs to the breastbone, known as costochondritis, can lead to referred back pain aggravated by breathing. This inflammation causes stiffness in the chest wall, restricting the rib cage’s movement. When attempting a full breath, the restricted movement places stress on surrounding back muscles and joints beneath the lats. The resulting sensation is a dull ache or sharp pain that intensifies during deep inhalation.
Respiratory and Inflammatory Causes
A more concerning cause of back pain triggered by breathing is pleurisy, which is inflammation of the pleura, the thin membranes surrounding the lungs and lining the chest cavity. Normally, these layers glide smoothly past each other, but inflammation causes them to rub together with each breath. The hallmark symptom of pleurisy is a sudden, sharp, or stabbing pain that worsens upon inhaling, exhaling, coughing, or sneezing.
This pain is typically felt in the chest but can radiate to the shoulder or back, often near the latissimus dorsi area. Pleurisy is often a complication of an underlying condition, such as a viral infection or pneumonia. Pneumonia causes inflammation that can spread to the adjacent pleura, leading to pain with breathing, often accompanied by a fever and a persistent cough.
The underlying structure of the rib cage itself can also be the source of respiratory-induced lat pain. A rib fracture or severe bruising from trauma causes intense pain whenever the rib moves. Since breathing requires constant rib movement, the injury is irritated with every expansion and contraction of the chest wall. This injury, even if minor, can cause muscle guarding in the overlying lats, resulting in a complex pain pattern.
Recognizing Serious Symptoms and Seeking Care
While muscle strain is the most common cause, simple rest, ice, and gentle stretching often resolve suspected strains within a few days. However, certain accompanying symptoms signal a need for prompt medical evaluation if the pain persists or is accompanied by other systemic signs.
Immediate medical care is necessary if the pain is associated with a fever or chills, which can suggest an infection like pneumonia. Severe shortness of breath, a sudden onset of crushing chest or back pain, or pain that spreads to the jaw or arm should not be ignored. Coughing up blood or colored mucus also requires immediate investigation.
Any pain that is unrelenting, severe, or prevents a full breath is a reason to seek professional care. These symptoms may indicate conditions more serious than a muscle strain, such as a pulmonary embolism (a blood clot in the lungs). A doctor can perform a physical examination and order diagnostic tests, such as a chest X-ray or blood work, to determine the source of the pain.