Swimmer’s shoulder is an overuse injury caused by repeated overhead arm movements that irritate the tendons and soft tissues around the shoulder joint. The most common source of pain is damage to the supraspinatus tendon, one of four rotator cuff tendons that hold the upper arm bone in its socket. Shoulder pain affects up to 91% of competitive swimmers at some point and is the leading cause of missed practice in the sport.
What Happens Inside the Shoulder
Every freestyle stroke cycle moves the arm through a wide arc of motion, and competitive swimmers repeat this motion thousands of times per practice. The space beneath the bony roof of the shoulder (the acromion) is narrow, and the rotator cuff tendons pass through it each time the arm rises overhead. When those tendons get pinched repeatedly in that gap, the result is subacromial impingement, the hallmark of swimmer’s shoulder.
The problem often starts with fatigue. Muscles that stabilize the shoulder blade, particularly the serratus anterior and upper trapezius, lose their ability to rotate the blade upward as a workout wears on. When the shoulder blade doesn’t rotate properly, the subacromial space shrinks, and the tendons get compressed with every stroke. Over time, this leads to tendon inflammation, fraying, and in some cases small tears. Instability can also develop: the ligaments and capsule of the shoulder stretch out from repetitive motion, allowing the humeral head to shift slightly upward and compress the tendons from below.
Stroke Errors That Increase Risk
Certain technique flaws place the shoulder in positions that mimic the exact maneuvers doctors use to test for impingement. A hand entry that crosses the body’s midline forces the shoulder into the same internally rotated, flexed position used in clinical impingement tests. Entering the water thumb-first stresses the biceps tendon where it attaches to the labrum, the ring of cartilage lining the shoulder socket.
A dropped elbow during the pull-through phase puts the propulsive muscles at a mechanical disadvantage, forcing smaller structures to compensate. An S-shaped pull pattern or pulling past the midline of the body increases time spent in the impingement zone. During the recovery phase, a dropped elbow means the elbow enters the water before the hand, and the water pushes the upper arm bone upward into the tight subacromial space.
Body roll matters too. Rolling less than about 45 degrees increases mechanical stress on the shoulder and sets up a poor hand entry angle. Rolling too far can cause the hand to cross over the midline on entry. Even head position plays a role: looking straight ahead instead of slightly downward restricts normal shoulder blade movement and promotes impingement.
Who Gets It and When
Adolescent swimmers report the highest rates of shoulder pain, with prevalence reaching 91% in some studies. Young swimmers (pre-adolescent) show rates up to 20%, adult competitive swimmers up to 70%, and masters swimmers around 19%. The jump during adolescence likely reflects the combination of rapidly increasing training volume, growth-related changes in shoulder anatomy, and technique that hasn’t yet matured. Training volume is one of the strongest predictors across all age groups.
How It Feels
The primary symptom is pain at the front of the shoulder that worsens with arm movement, especially overhead activity. In early stages, pain may appear only during or after hard training sessions and fade with rest. Coaches often notice a dropped elbow during the recovery phase of freestyle before the swimmer even reports pain. This happens because the shoulder instinctively avoids painful inward rotation by lowering the elbow, which reduces the rotational demand on the joint.
As the condition progresses, swimmers may develop exaggerated body roll to compensate, and the shoulder blade may begin “winging” (its inner edge lifts visibly away from the rib cage). In advanced cases, the shoulder becomes weak enough that it can’t resist even light manual pressure during strength testing. At this point, pain typically occurs with everyday activities like reaching for a seatbelt or sleeping on the affected side.
How It’s Diagnosed
Diagnosis is largely clinical. Two standard physical exam maneuvers are commonly used. In the Neer test, the examiner stabilizes your shoulder blade and slowly lifts your arm forward in a semicircle. Pain during this motion suggests impingement. In the Hawkins-Kennedy test, the examiner positions your arm forward at 90 degrees with the elbow bent and then rotates your forearm downward toward your chest. Pain here also points to impingement. Imaging is generally reserved for cases where symptoms persist despite treatment or a more serious injury like a labral tear is suspected.
Treatment and Rehabilitation
The first step is usually reducing training volume or temporarily modifying strokes to avoid painful positions. Complete rest from swimming isn’t always necessary, but continuing to train through significant pain risks turning a recoverable tendon irritation into a structural tear.
Rehabilitation targets the muscles that stabilize the shoulder blade, since their weakness is typically at the root of the problem. The serratus anterior is a priority because it holds the scapula in the correct position and maintains adequate clearance for the rotator cuff tendons. Exercises that promote scapular protraction (pushing the shoulder blade forward against resistance) are a common starting point. Slide board exercises, where you move your hand along a surface while keeping the shoulder blade pressed forward, are one approach used in physical therapy clinics.
The lower trapezius, which controls downward and inward stabilization of the shoulder blade, also gets targeted. A typical exercise involves lying face down with the arm angled out at about 150 degrees and the elbow bent to 90 degrees, then lifting the hand off the table by externally rotating the shoulder. The middle trapezius and rhomboids round out the scapular stability program.
Rotator cuff strengthening comes alongside scapular work, with particular attention to the external rotators that counterbalance the dominant internal rotation forces of swimming. Recovery timelines vary, but most swimmers with early-stage symptoms improve within several weeks of modified training and consistent rehabilitation. Advanced cases with significant weakness or structural damage can take months.
Prevention With Dryland Training
A resistance band program targeting the shoulder rotators has shown effectiveness in reducing injury rates among competitive swimmers. One evidence-based protocol uses four exercises performed three times per week:
- Shoulder press: Starting with elbows bent and hands above the shoulders, press upward to full arm extension and return slowly.
- External rotation at 90 degrees: With the arm out to the side and elbow bent at 90 degrees, rotate the forearm upward until the hand is level with the head.
- Shoulder flexion above 120 degrees: From a standing position with thumbs up, raise both arms past 120 degrees and return slowly.
- Low scapular rows: With elbows bent at 45 degrees, pull the elbows back in a rowing motion focusing on squeezing the shoulder blades together.
Each exercise is performed for three sets of 20 repetitions with 30 seconds of rest between sets and one minute between exercises. Resistance bands provide the load, with the band color (and therefore resistance) matched to the swimmer’s ability. To set the right starting level, swimmers perform two sets of 20 repetitions plus a final set to exhaustion. If they complete 30 repetitions on that last set with good form, they move up to the next resistance level.
Beyond dryland work, stroke technique correction is arguably the most important preventive measure. Having a coach or video analysis identify crossover entry, dropped elbows, inadequate body roll, or forward head position can eliminate the mechanical triggers before they cause tissue damage. Managing training volume, especially during periods of rapid growth in adolescents, reduces the cumulative load on already vulnerable structures.