Overview

Pectoralis major injuries range from mild muscle strains to complete tears of the muscle or its tendon. They are relatively rare, and the most common mechanism is the bench press — particularly the bottom position, where the chest muscle is loaded while the arm is extended and rotated outward.

A strain is a stretched or partially torn muscle-tendon unit. A tear — partial or complete — means more tissue has been disrupted. The biggest clues are not pain alone: a pop, rapidly developing bruising, a change in the front of the armpit, or an immediate loss of pressing strength all raise concern for a larger tear.

Typical Pattern

Sudden pain or a pop during a bench press, dip, throw or awkward reach
Pain in the chest or front of the armpit, worse with pressing or bringing the arm across the body
Bruising that can appear hours later in the chest, armpit or upper arm
Weakness pressing, or difficulty lowering the arm from an outstretched position
With a complete tear, a visible change in the anterior axillary fold — the front border of the armpit formed by the pectoralis major

Why It Develops

The pectoralis major is loaded heavily during pressing. Tears usually happen when the muscle contracts while being stretched — the eccentric phase of a bench press, a catch during sport, or a forceful throw. The lower (sternocostal) fibres are particularly vulnerable when the arm is extended and externally rotated.

Fatigue, sudden increases in load, prior injury and technique all change how much stress the tissue can tolerate. The injury can also happen in contact sports, wrestling, water sports, or a fall onto an outstretched arm.

How It Is Diagnosed

A clinician combines the mechanism, symptoms and examination. The key questions are where the injury is (tendon versus muscle belly), how much is torn, and whether there is a complete rupture.

Ultrasound or MRI is often used to confirm the location and severity. This matters because complete tears of the tendon at its attachment heal less predictably on their own, while many muscle-belly and partial tears do well without surgery.

Treatment

The first priority is an assessment when a pop, bruising, deformity or marked weakness is present — not repeated testing of the injury with pressing movements.

Mild to moderate strains: protected early loading, then a graded return through isometric work, shallow presses and eventually the specific lift. See the return-to-pressing guide.
Partial tears: usually non-surgical, with the same graded loading approach and a longer, more cautious timeline.
Complete tendon tears: surgical repair is commonly recommended for young, active people, with evidence of improved strength and return to sport. Repair should happen relatively early when it is chosen.
Muscle-belly tears: often managed non-surgically, depending on the degree and function.

Rehabilitation matters whether or not surgery is performed. The usual progression is settle the irritation, restore motion, rebuild strength, then return to pressing loads.

When to Get Assessed

Arrange an assessment for any sudden chest injury with a pop, bruising, deformity or immediate weakness, ideally within the first week when a complete tear is possible.

Chest pain can also be cardiac, so if pain feels heavy, tight or pressing, spreads to the arm or jaw, or comes with shortness of breath, sweating or nausea, treat it as urgent — see chest pain red flags before assuming a muscle cause.

References

StatPearls. "Pectoralis Major Tear." https://pubmed.ncbi.nlm.nih.gov/31751065/
Yu J, et al. "Outcomes and Return to Sport After Pectoralis Major Tendon Repair: A Systematic Review." Sports Health. 2019. https://pmc.ncbi.nlm.nih.gov/articles/PMC6391551/
Long C, et al. "Injuries of the Pectoralis Major: Diagnosis and Management." Orthopedic Reviews. 2022. https://pmc.ncbi.nlm.nih.gov/articles/PMC9797018/

This information is for education only and is not a medical diagnosis. InjuryAtlas does not replace an assessment by a qualified health professional. If you have severe pain, visible deformity, numbness, loss of function, or symptoms that are getting worse, seek medical care promptly.

Pectoralis Major Strain & Tear