Swimmer’s shoulder

  • Physiology & performance

Swimmer's Shoulder: What causes it, how to prevent it, and how to treat and rehab it.

This article isn’t medical advice, and nothing here should stop you from seeing a doctor if your shoulders are giving you trouble. Think of it instead as a starting point — a way to understand why these injuries happen, so you can head them off before they do.

1. The Shoulder

The shoulder is one of the hardest-working joints in swimming, whatever your level — from beginner to seasoned racer.

Here’s why: over 80% of your propulsion comes from your arms (sometimes more, depending on the swimmer and the stroke), which puts a huge load on the shoulders.

A regular swimmer — nowhere near elite level — will average 40 to 50 stroke cycles per minute (one cycle being a full arm movement, from start back to start). That means each shoulder fires more than 2,000 times per hour of swimming.

💡 KEY FIGURES
  • Over 80% of your propulsion comes from your arms
  • Average 40 to 50 stroke cycles per minute
  • 2,000 shoulder use per hour of swimming.

2. What Causes These Injuries

1 – Technique breakdown 

Since the shoulder does so much of the propulsion work, small flaws in positioning become a real problem once you repeat them hundreds or thousands of times over months of training. It’s a bit like an engine part that’s off by a few millimeters — the engine still runs, but eventually that tiny misalignment creates a breaking point.

2 – Overtraining 

Wanting to improve naturally pushes swimmers — beginners and veterans alike — to swim more often and further. That’s fine, as long as you build up gradually. Double or triple your training overnight, though, and your body will eventually push back: muscle, tendon, ligament, or joint pain.

A quick reminder of what you’re working with: the shoulder is a complex joint made up of three bones (humerus, clavicle, and scapula), around twenty muscles — each with tendons at both ends, including the four rotator cuff muscles and the deltoid, which take a particular beating in swimmers — and a network of stabilizing ligaments (glenohumeral, coracohumeral, coracoclavicular, coracoacromial, and more).

It’s a delicate system, so pay attention to fatigue signals before they turn into actual damage.

3 – Equipment 

Swimmers love their gear — it mixes up training and helps build strength and skill. For the shoulders specifically, paddles are the usual culprit. Bigger paddles mean more resistance and more power, and the times they produce can feel incredible — which makes them tempting to overuse.

But that pulling power comes at a cost: paddles double or triple the surface area pulling against the water compared to your bare hand, putting far more strain on the joint. Used without control — or without addressing point (a) above — tendons and ligaments tend to end up inflamed.

4 – Outside factors (medical treatments, accidents…)

Beyond training-related causes, a few other things can trigger shoulder pain:

  • Medications. Some drugs are known to cause tendon issues as a side effect — fluoroquinolone antibiotics, for example. This is usually listed in the drug’s official information.
  • Unrelated accidents. A car accident, a bike fall, or any other incident can shift your body’s internal balance and create unusual tension elsewhere — the shoulder isn’t spared, and this shows up often after neck injuries.
  • Diet. Certain foods are linked to tendon and ligament issues. Some people don’t tolerate dairy well, for instance, and the same goes for gluten and other allergens.
  • Dehydration. Your body is 50–60% water (depending on sex and body composition), and that water is essential for your muscles and tendons to work properly. A dehydrated body is a weaker one — and since the shoulder handles most of your propulsion and power, it’s often first in line for trouble.

3. Solutions and How to Take Care of Your Shoulders

Work on your technique

Improving your technique and swimming more efficiently is non-negotiable if you want to swim long distances. Swimming is a highly technical sport, and self-correcting is genuinely hard — your best bet is taking lessons or joining a club to get expert eyes on your stroke.

A coach can also help here — guiding you through a sensible progression, whether that’s your weekly session count or the distance you’re covering. Your body can absorb gradual increases, as long as they actually fit into your life (cutting into your sleep to squeeze in training, for example, is asking for trouble down the line).

If you know your shoulders are a weak point, adjust your gear right away  rather than waiting for an injury to force the issue. Sure, you won’t hit your usual “supersonic” set times — but you’ll protect your shoulders and, more importantly, your enjoyment of the sport.

Nothing’s fun once your body starts sounding the alarm.

If you’ve already had shoulder pain, tracking down the actual cause is the only way to fix it and keep enjoying your training.

Knowing your allergies and intolerances — food or medication — is on you, and so is doing something about it.

A more balanced lifestyle helps too: enough quality sleep, less alcohol, fewer stimulants — none of which mix well with a sport you’re supposed to enjoy.

Beating shoulder pain (or preventing it) comes down to simple routines that fit naturally into your training and help you get the most out of it. A few habits worth building in:

  • Stretch regularly
  • Do a dryland warmup routine before getting in the water
  • See an osteopath periodically to check your overall body balance
  • See a physiotherapist as soon as tension shows up — before it settles in and gets worse
  • Drink plenty of water
  • If your training load is heavy, add electrolytes to help your body stay balanced
  • Build in regular rest days so your body can absorb the work
  • Learn to listen to your body — it’s your most valuable tool for getting the most out of every session