Your Shoulder Only Works Half the Time You're Paddling

Every session, you climb on your board and paddle. Paddle out through the break. Paddle for waves. Paddle back out. Depending on conditions, you might spend 44 to 61 percent of your time in the water doing exactly this — a statistic that should make every surfer stop and think about what that movement is actually training [1].

Here's what it isn't training: the back half of your shoulder. The muscles that pull your shoulder into external rotation — the infraspinatus, teres minor, and the lower portions of your trapezius — get almost no meaningful resistance work during a paddle stroke. The internal rotators, meanwhile, are working hard against the full resistance of water every single time your hand pulls through. Over thousands of strokes, you're systematically building one side of a joint and leaving the other largely untrained. That asymmetry, not paddling per se, is the root cause of surfer's shoulder.

The fix isn't to paddle less. It's to train the half of your shoulder that paddling misses.

What Actually Happens During a Paddle Stroke

To understand the problem, you need to see the stroke in three phases — because each phase loads different structures, and the imbalance isn't random.

The catch phase is when your arm reaches forward and overhead to enter the water. Mechanically, this is shoulder flexion and elevation into a range where the subacromial space is at its narrowest — the same anatomical region clinicians provoke during impingement testing. The deltoid, infraspinatus, and upper trapezius are all measurably active here [2], with the supraspinatus recruited to initiate abduction and to stabilize the humeral head in the glenoid throughout elevation. Its tendon passes directly through the subacromial space, which is why it's the classic impingement target — not because it's the strongest elevator, but because it's the most mechanically exposed [1].

The propulsion phase is where the real work happens. From approximately 90 degrees of shoulder flexion, your arm internally rotates and extends as your hand drives water backward. The prime movers are your pectoralis major, latissimus dorsi, and subscapularis — your internal rotators, firing hard against full water resistance. This is the engine of forward motion, and it is entirely dominated by the anterior chain [2, 3, 4]. Worth noting: these are also the muscles spending the most time in a shortened position during each stroke recovery. Over thousands of repetitions, they don't just get stronger — they get tighter, and that progressive anterior chain shortening is part of what drives the postural drift described in the next section.

The recovery phase is the arm's return swing from hip to entry. It's the only window in the stroke where the scapular muscles — including all three parts of the trapezius — get their peak activity. It's also the only phase where the shoulder externally rotates. And it happens against gravity alone, not water. There is no external resistance on the return [4].

Read that again: your shoulder only externally rotates when your arm is out of the water. Internal rotation works against full water resistance hundreds of times per session. External rotation gets a single unloaded pass on the swing back. Repeat this asymmetry for years, and the joint adapts accordingly.

Research confirms the consequence. Studies of competitive surfers consistently find internal rotator strength significantly greater than external rotator strength [5, 6]. The functional ratios used in throwing athletes — where an ER:IR ratio below roughly 0.66 is considered a risk factor — don't necessarily translate directly to surfers, but the direction of the imbalance is clear and consistent across the surfer studies. The signature deficit of surfer's shoulder is reduced external rotation range of motion — the opposite of thrower's shoulder, where it's internal rotation that suffers [1]. In the sports medicine literature, this pattern falls under rotator cuff-related shoulder pain (RCRSP), or subacromial pain syndrome (SAPS) when the subacromial space is specifically involved. Same joint, opposite deficit from throwing. This matters because generic "shoulder mobility" advice borrowed from throwing sports may actively worsen a surfer's shoulder by pushing further into the direction the joint is already overloaded.

How the Scapula Gets Dragged Into It

The shoulder joint doesn't exist in isolation. What happens at the scapula determines whether the humerus has room to move overhead without impinging on the acromion — and the paddle stroke degrades scapular mechanics in a predictable way.

The pectoralis major, pectoralis minor, subscapularis, and lats that dominate the propulsion phase all pull the shoulder into anterior tilt, protraction, and downward rotation when chronically shortened. This is also, not coincidentally, the resting scapular position that years at a desk produce. A surfer who works at a computer is stacking two mechanical insults: chronic anterior-chain shortening from sitting, then repetitive overhead loading in internal rotation during paddling. The scapula ends up tilted forward, wings away from the rib cage, and rotated downward — narrowing the subacromial space exactly when the arm is reaching overhead for the catch.

Clinical examination studies have found scapular dyskinesis — abnormal scapular movement patterns — in a high proportion of surfers studied [1]. The mechanism is hypothesized, though not yet proven in surfers directly, to involve pectoralis minor shortening as an underappreciated contributor: a shortened pec minor changes the scapula's resting kinematics in ways that mirror what's seen in subacromial pain syndrome [1].

Surfer-specific posture compounds this further. Unlike swimmers, who rotate along their long axis with the head in line with the spine, surfers paddle prone on a board — neck and thorax extended, looking forward and upward to read waves. This sustained hyperextended position is itself associated with scapular dysfunction independent of the stroke. Decreased thoracic extension narrows the subacromial space. Studies in adults over 40 have found thoracic kyphosis associated with higher rates of subacromial impingement syndrome, mediated largely through reduced shoulder elevation [7]. A 2025 RCT found that adding thoracic mobilization to standard shoulder rehab produced greater improvements in acromiohumeral distance, pain, and function than exercise alone [8]. The causal picture isn't fully settled — the relationship between resting kyphosis and shoulder pain may be more associative than directly mechanistic — but the practical implication for a surfer with tight thoracic extension is worth taking seriously.

The Upper Trap Problem That Isn't What You Think

Here's where the usual advice goes wrong.

Most content about surfer's shoulder tells you to "stop shrugging when you paddle" or "turn off your upper trap." This is mechanistically incorrect, and following it would make things worse, not better.

The upper trapezius has a necessary job during arm elevation: it works with the lower trap and serratus anterior to produce upward rotation of the scapula — the motion that tilts the shoulder socket upward so your arm can get overhead without the humerus running into the acromion. This is a force couple: three muscles pulling in different directions to produce one coordinated rotation.

The upper trap pulls the acromion up and in. The lower trapezius pulls the scapular spine down and in. The serratus anterior pulls the inferior angle forward around the rib cage. All three firing together produces smooth, controlled upward rotation. Any one of them dominating produces dysfunction.

In most surfers with shoulder problems, the upper trap isn't the villain — it's the understudy playing the lead because the actual leads aren't showing up. EMG studies of scapular dyskinesis consistently show an elevated upper-trap-to-lower-trap activation ratio: the upper trap working two or three times what it should relative to the lower trap. The absolute upper trap activity may be entirely normal. It's lower trap inhibition that creates the pattern, and the upper trap looks overactive by comparison [1].

There's also a timing problem. In healthy scapular mechanics, the lower trap and serratus initiate upward rotation and the upper trap joins in. In dysfunctional patterns — which desk workers, in particular, develop over years — the upper trap fires first and hardest, producing scapular elevation (a shrug) rather than upward rotation. Instead of the scapula rotating around its own axis, it rides toward the ear. During the pull phase, the upper trap should quiet down; in many surfers, it stays tonically active through the whole stroke cycle. That's why people finish a session with a burning ring of tension across the tops of the shoulders and the base of the neck — the "coat hanger" distribution — as the dominant sensation.

The cue that actually works isn't "stop shrugging." It's: "Long neck, shoulders wide." Keep the neck long — not compressed by shoulders climbing toward the ears — and think about your shoulder blades staying wide across your back, held against the rib cage by the serratus, rather than hiking upward or pinching together. Paddle with that sensation and your upper trap is doing its job as part of the team rather than running the show.

What to Train — Ranked by Evidence Strength

1. Rebalance Internal and External Rotation

The most direct fix for the most direct problem. Your internal rotators are strong. Your external rotators are not. The Surfing Medicine International protocol, developed by the researchers responsible for the most comprehensive systematic review of surfer's shoulder, centers on this rebalancing [1]:

Sidelying External Rotation

Setup: Lie on your non-working side, elbow bent to 90 degrees, upper arm against your ribs. Hold a light dumbbell in your top hand, palm facing the floor.

The movement:

1. Keeping your elbow pinned to your side, rotate your forearm upward toward the ceiling.
2. Stop when the forearm is vertical or just past — don't let the elbow drift away from the body.
3. Lower slowly and with control.

What right feels like: You should feel work in the back and outer portion of the shoulder — the infraspinatus and teres minor. The movement should be small and controlled, not a wide, sweeping arc. Your elbow stays glued to your ribs throughout.

Common mistakes:

• If your elbow drifts away from your body: You're recruiting deltoid. Reset and pin the elbow back.
• If you feel strain in the front of the shoulder: Your range is too large. Reduce the arc.
• If the weight feels easy at 3×15: It's probably too light. External rotators are small but capable of more than people give them credit for. Progress to a weight that makes reps 12–15 genuinely challenging.

Dosage: 3 sets of 12–15 reps each side, 3–4 days per week. Progress to 90-degree abduction once the 0-degree version is controlled.

Pectoralis Minor Stretch

The pec minor is the underappreciated driver of scapular anterior tilt. When it shortens — which sustained paddling and desk posture both encourage — it tips the scapula forward and narrows the subacromial space even at rest. Stretching it directly addresses the postural component of the problem.

Setup: Stand in a doorway, raise your arm to roughly 90 degrees of abduction (elbow bent, forearm resting against the door frame). Take a small step forward with the same-side foot.

The movement:

1. Gently rotate your chest away from the door frame, letting the front of the shoulder open.
2. You should feel the stretch across the front of the chest and into the coracoid region — just below the collarbone, toward the shoulder.
3. Hold without forcing. Let the stretch deepen with each exhale.

What right feels like: A lengthening sensation across the anterior chest, distinct from shoulder joint pain. Breathing should be easy throughout. If you feel tension or pinching in the front of the shoulder joint rather than the chest, back off the rotation slightly.

Common mistakes:

• If you feel nothing across the chest: Your rotation isn't sufficient, or your arm position is too high. Try dropping the arm slightly toward 70–80 degrees and rotating more deliberately.
• If you feel strain in the front of the shoulder joint: You've gone too far, or the arm is positioned too high. The stretch should be felt in the muscle belly, not the joint.

Hold: 30–45 seconds per side or until you feel the initial tension ease, 3 repetitions. Breathe steadily throughout — if you're holding your breath, reduce the stretch angle slightly.

2. Retrain the Scapular Force Couple

Strengthening the lower trapezius and serratus anterior specifically — not just doing generic "back work" — is what shifts the upper-trap dominance pattern. A 6-week scapular rehabilitation program in overhead athletes with impingement symptoms reduced SPADI (shoulder pain and disability) scores significantly and measurably decreased the upper-trap-to-serratus anterior ratio — the exact imbalance driving the dysfunction [9]. A more recent RCT found that scapular-dyskinesis-targeted exercise produced greater gains in lower trap, middle trap, serratus anterior, and external rotator strength than generic physical therapy, with large effect sizes maintained after the intervention ended [10].

One caveat worth noting: 6 weeks appears sufficient to change activation amplitudes and ratios, but the same research found it was not sufficient to change muscle onset timing. Sequencing corrections — getting the lower trap to fire before the upper trap, not just harder — likely require longer training windows and more deliberate motor control work [9].

Prone Y Raise

This is the cornerstone of lower trap retraining. Research confirms that adding a scapular depression cue — actively drawing the shoulder blade down before and during the lift — significantly increases lower trapezius activity during the movement [11].

Setup: Lie face down on a bench or firm surface, arms hanging straight toward the floor, thumbs pointing toward the ceiling. You can do this with bodyweight, light dumbbells, or a resistance band anchored at the floor.

The movement:

1. Before you lift, draw your shoulder blades gently downward — not pinching together, but sliding down your back. This is the depression cue.
2. Lift both arms in a Y shape (roughly 135 degrees from the body) until they're level with your torso or just above.
3. At the top, maintain the scapular depression — resist the urge to let the shoulders shrug toward the ears.
4. Lower slowly, reset the scapular position, and repeat.

What right feels like: The working sensation should be in the mid-to-lower back of the shoulder — lower trap territory — and the area between your shoulder blades. You should not feel your shoulders climbing toward your ears. If you do, you've either loaded too heavily or lost the depression cue.

Common mistakes:

• If your shoulders shrug at the top: You've lost the lower trap and defaulted to upper trap. Lower the weight or resistance significantly and practice the cue with no load at all until it's automatic.
• If you feel it primarily in the upper back between the shoulder blades: You're doing a retraction movement more than a Y. Check your arm angle — it should be wider than a T.
• If your lower back arches: Your core isn't engaged, or the surface isn't supporting you properly. Focus on keeping the ribcage gently pressed into the bench throughout.

Dosage: 3 sets of 10–12 reps, 3 times per week. Progress to light dumbbells only when the bodyweight version feels controlled and the lower trap is clearly working.

Serratus Push-Up (Scapular Push-Up)

Setup: Plank position, hands directly under shoulders, body in a straight line from head to heels.

The movement:

1. Without bending the elbows, allow your chest to sink slightly toward the floor as your shoulder blades pinch together (protraction releases).
2. Then actively push the floor away — let your upper back round slightly as the shoulder blades spread wide around the rib cage. That spreading is the serratus working.
3. This is a small, deliberate movement — not a push-up.

What right feels like: The working sensation is around the sides of the rib cage — the serratus anterior running in strips from the scapular border to the ribs. Many people have never felt this muscle work before. It can take several sessions to feel it clearly.

Common mistakes:

• If the movement is coming from the arms: You're doing a mini push-up, not a scapular movement. Keep the elbows locked throughout.
• If you feel it only in the shoulders and chest: You're not completing the protraction — push the floor harder at the end range until you feel the shoulder blades spread.

Dosage: 3 sets of 10–15 reps. Progress to a single-leg plank position once bodyweight is controlled.

Prone T Raise

The Y raise targets the lower trap; the serratus push-up targets the serratus anterior. The prone T fills the remaining gap: middle trap and rhomboids, which counter the protraction and forward tilt that paddling progressively drives the scapula into.

Setup: Same position as the Y raise — face down on a bench or firm surface, arms hanging toward the floor, thumbs pointing toward the ceiling.

The movement:

1. Apply the same scapular depression cue as the Y raise — shoulder blades sliding down before you lift.
2. Lift both arms out to the sides in a T shape (roughly 90 degrees from the body, perpendicular to the torso).
3. At the top, think about the shoulder blades drawing together and down — not just up.
4. Lower slowly and reset.

What right feels like: The working sensation should be in the mid-back between and below the shoulder blades — middle trap and rhomboid territory. The movement is smaller than it looks. If you're swinging the arms, the load is too heavy.

Common mistakes:

• If your shoulders shrug at the top: Same error as the Y raise — you've lost the depression cue and the upper trap has taken over. Reset with no load.
• If you feel it mostly in the upper back and neck: Your arms are too high — angle them slightly downward toward a Y position.
• If the movement feels too easy: Add very light dumbbells. The middle trap responds well to moderate load; don't stay at bodyweight indefinitely.

Dosage: 3 sets of 10–12 reps, 3 times per week. Pair with the Y raise in the same session — they're complementary and together take less than ten minutes.

3. Thoracic Mobility

A brief but worthwhile addition to the routine, particularly for surfers who also spend significant time at a desk. Emerging RCT evidence supports thoracic mobilization as an adjunct to shoulder rehab — not as a primary fix, but as a facilitator of better shoulder mechanics [8].

Foam Roller Thoracic Extension

Setup: Place a foam roller horizontally across the mid-back at roughly shoulder blade level. Support your head with your hands, elbows forward. Feet flat on the floor, knees bent.

The movement:

1. Gently let your upper back extend over the roller, using gravity rather than forced pressure.
2. Hold at the comfortable end range for 5–10 slow breaths.
3. Shift the roller one position up or down the spine and repeat.

What right feels like: A gentle opening sensation across the mid-back. You may hear or feel a soft release. This should not be painful — if it is, shift the roller position or reduce the extension.

Dosage: 3–5 positions along the thoracic spine, 5–10 breaths each. Perform before your shoulder strengthening routine.

The In-Water Reset

This is the practical complement to the gym work — something you can use between waves to prevent the pattern from drifting back toward upper-trap dominance. The trigger: do it after each wave, or each time you turn the board around to paddle back out. You don't need to check a watch — the natural rhythm of a surf session gives you the cadence.

1. Exhale fully.
2. Let your shoulder blades slide down your back — not pinch together. Down.
3. Feel your neck lengthen.
4. Take one or two paddle strokes consciously holding that position.
5. Let it automate.

That's it. A minute of deliberate reset redistributes the load from the upper trap back toward the lower trap and serratus, where it belongs. It won't fix a structural imbalance, but it slows the drift toward the dysfunction pattern during a session.

What Not to Do

A few things the surfing shoulder literature explicitly flags as counterproductive:

Don't do aggressive overhead stretches. Generic shoulder mobility work borrowed from gym culture — barbell overhead mobility, doorway chest stretches that load into further internal rotation — can worsen impingement symptoms in surfers already pushed into IR at the catch. If a stretch loads the shoulder further into internal rotation at the end of elevation, it's moving in the wrong direction.

Don't assume more paddling builds a balanced shoulder. It doesn't. The paddle stroke will always load internal rotation more than external. That's not a correctable technique problem; it's the physics of pulling through water. The solution is supplementary loading, not technique optimization alone. And if you're increasing your time in the water — longer sessions, more days per week — apply the same 10% weekly progression principle used in running and other endurance sports. The shoulder's connective tissue adapts more slowly than the cardiovascular system does.

Don't wait for pain. Strength imbalance has been measured in competitive surfers across symptom states [5], and in adjacent overhead sports it has been shown to predict future shoulder injury — making it a reasonable target for prehab work before symptoms develop. The time to address it is during the off-season, during flat spells, or simply as a standing habit — not after the shoulder starts clicking during the catch.

The Bigger Picture

Surfer's shoulder is a clarifying example of a principle that applies well beyond the water: the body adapts specifically to the loads you give it. It doesn't compensate for what you don't train. It doesn't redistribute work to keep things balanced. It gets good at exactly what you repeat.

Paddling trains the anterior chain — hard, frequently, and against real resistance. The posterior chain gets an unloaded pass on the recovery swing. For occasional surfers, the imbalance may stay subclinical indefinitely. For people who surf regularly and also sit at a desk for eight hours a day — stacking anterior-chain dominance on anterior-chain dominance — the joint is getting a clear signal, and that signal only points one direction.

The intervention isn't complicated. It's the boring, consistent work of training what you're not training, stretching what you're shortening, and paying attention to a few kilograms of force couple mechanics at the top of each stroke. That's not a glamorous program. But it's the one that keeps you in the water.

Open Sorely, tap Shoulders, and follow the guided paddle prep routine.

References

1. Langenberg, L. C., Vieira Lima, G., Heitkamp, S. E., Kemps, F. L. A. M., Jones, M. S., Moreira, M. A. A. G., & Eygendaal, D. (2021). The surfer's shoulder: A systematic review of current literature and potential pathophysiological explanations of chronic shoulder complaints in wave surfers. Sports Medicine — Open, 7(1), 2. https://doi.org/10.1186/s40798-020-00289-0

2. Nessler, J. A., Silvas, M., Carpenter, S., & Newcomer, S. C. (2015). Wearing a wetsuit alters upper extremity motion during simulated surfboard paddling. PLoS One, 10(11), e0142325. https://doi.org/10.1371/journal.pone.0142325

3. Nessler, J. A., Ponce-Gonzalez, J. G., Robles-Rodriguez, C., Furr, H., Warner, M., & Newcomer, S. C. (2019). Electromyographic analysis of the surf paddling stroke across multiple intensities. Journal of Strength and Conditioning Research, 33(4), 1102–1110. https://doi.org/10.1519/JSC.0000000000003070

4. Pexa, B. S., Johnston, C. D., Elder, E. E., Ford, K. R., Patterson, M. Q., & Myers, J. B. (2024). Pool-based surfboard elicits activation of posterior shoulder muscles during a surfing stroke. Journal of Strength and Conditioning Research, 38(7), 1300–1304. https://doi.org/10.1519/JSC.0000000000004791

5. Furness, J., Schram, B., Cottman-Fields, T., Solia, B., & Secomb, J. (2018). Profiling shoulder strength in competitive surfers. Sports, 6(2), 52. https://doi.org/10.3390/sports6020052

6. Madeira, M., Nobre, P., Costa, T., Almeida, V., Paulo Sousa, J., & Pereira, Â. M. (2019). Isokinetic profile of the shoulder internal and external rotators in surfers. Annals of Medicine, 51(sup1), 218. https://doi.org/10.1080/07853890.2018.1560727

7. Otoshi, K., Takegami, M., Sekiguchi, M., Onishi, Y., Yamazaki, S., Otani, K., Shishido, H., Kikuchi, S., & Konno, S. (2014). Association between kyphosis and subacromial impingement syndrome: LOHAS study. Journal of Shoulder and Elbow Surgery, 23(12), e300–e307. https://doi.org/10.1016/j.jse.2014.04.010

8. Calik, M., Kara, D., Terzi, M. M., Bezirgan, U., Misirli, S., Kaya Utlu, D., & Duzgun, I. (2025). Effect of thoracic mobilization on acromio-humeral distance, thoracic kyphosis angle, pain and shoulder function in patients with subacromial impingement syndrome: A randomized controlled trial. European Spine Journal. https://doi.org/10.1007/s00586-025-09144-w

9. De Mey, K., Danneels, L., Cagnie, B., & Cools, A. M. (2012). Scapular muscle rehabilitation exercises in overhead athletes with impingement symptoms: Effect of a 6-week training program on muscle recruitment and functional outcome. American Journal of Sports Medicine, 40(8), 1906–1915. https://doi.org/10.1177/0363546512453297

10. Wen, M., Hu, X., & Bao, G. (2025). Scapular dyskinesis-based exercise therapy versus multimodal physical therapy for subacromial impingement syndrome in young overhead athletes with scapular dyskinesis: A randomized controlled trial. BMC Sports Science, Medicine and Rehabilitation, 17(1), 204. https://doi.org/10.1186/s13102-025-01254-8

11. Yu, I. Y., Lim, N. D., Kim, G. B., Lee, D. H., Du, R., & Kim, T. G. (2025). Effectiveness of the scapular depression strategy to activate the lower trapezius during prone Y exercise. Isokinetics and Exercise Science. https://doi.org/10.1177/09593020251323792