Clearly shoulder injuries are the main injury in swimmers due to the volume of revolutions at the shoulder joint for training. If you’ve been following my articles on various websites, you’re well aware I write a lot about the shoulder. These pieces provide numerous tips and tidbits for improvement. Here are a list of some pieces I’ve written on the subject.

For an extremely detailed review of injury prevention and rehabilitation, please checkout the COR Swimmer’s Shoulder System. I know this is a blatant plug for my product, but these extremely in depth piece discusses swimmer’s shoulder from multiple angles, highlighting the main issues, while providing practical methods for improvement. This system has helped thousands of swimmers stay healthy, and more importantly, returned many to the pool pain free.

This article is based a lot of a research in depth review of risk factors for shoulder injury. Allan Phillips and myself put a lot of research into our Troubleshooting System, helping determine which screening techniques are best for swimmers. Currently, there is no universal screening system best for swimmers, as the Functional Movement Screen (FMS) is often used. I’ve discussed this topic with many in the swimming community and all agree, screening is a must, but the FMS is likely missing the boat for swimmers. Allan Phillips and myself discuss this on the Swimming Science Podcast and I discussed this in a USA Swimming webinar. Nonetheless, this is a detailed review of potential risk factors for shoulder injury, providing more useful information which complements the Troubleshooting System

Here are 18 potential risk factors for shoulder injury. What do you think are additional risk factors? Do you have any to add or what do you on the pool deck?

18 Potential Risk Factors for Shoulder Injury

1. Shoulder Internal/external rotation

Six studies have investigated whether the internal/external rotation was associated with shoulder pain in swimmers. Although research suggests swimmers with shoulder impingement pain had significantly decreased shoulder internal rotation and insignificantly increased external range of motion compared to swimmers without swimmer’s shoulder (shoulder impingement), it isn’t clear if this is a cause of an effect. However, with combination of the results from other studies, it seems there is sufficient evidence for shoulder internal and external range of motion as a risk factor for swimmer’s shoulder (shoulder impingement). 

2. Clinical joint laxity and instability

The available evidence suggests that joint laxity and instability is a risk factor for shoulder pain in swimmers, but the size of these studies is quite small and the testing for these conditions is not the same. Nonetheless, there is a moderate level of evidence that joint laxity and instability are a risk factor for swimmer’s shoulder. 

3. Internal/external rotation strength18 Risk factors for swimmer's shoulder

Five studies have analyzed internal and external rotation strength ratio for swimmer’s shoulder. The results are mixed and this is likely due to a low number of participants, large difference in testing and large variation in those tested. Therefore, the possibility of an internal and external rotation strength ratio as a risk factor for swimmer’s shoulder is low or not well researched.

4. Shoulder flexibility

Currently, it seems there is poor research on flexibility and shoulder injuries. Many coaches feel like there is a correlation between shoulder injury and poor flexibility, but the research on this topic uses mixed subjects and varying tests. 

5. Glenohumeral translation

The gelnohumeral joint is the joint where the upper arm (humerus) rests on the shoulder blade. Two studies found no association between glenohumeral translation and shoulder pain.

6. Training load, volume and intensity

Swimming training is a wide ranging risk factor for swimmer’s shoulder and shoulder injury in swimmers. Overall, the research does not disect these variables closely enough to safely consider any of them a risk factor. Overall, a handful of studies have suggested training volume is a risk factor of swimmer’s shoulder, but there is a lot of variation between studies. Therefore, the risk factor of training load, volume, and intensity is relatively low.

7. Stroke distance and stroke specialty

Many believe swimming butterfly is a risk factor for shoulder pain, but only one of eight studies have found an association between swimming stroke specialty and swimmer’s shoulder or shoulder pain. however, the research doesn’t adequately break down the total volume of stroke specialty training, simply the stroke specialty of the swimmer, so the research requires more in depth analyze of daily training habits. 

8. Years of swimming experience

Many would think, the longer you swim, the greater shoulder stress and injury, but it isn’t this simple. Four out of six studies analyzing years of experience and swimmer’s shoulder found no association. Therefore, the idea of years of swimming experience as a risk factor for swimmer’s shoulder is low.

9. Breathing side

Breathing alters swimming biomechanics, which may increase shoulder stress. Overall, the research considers breathing side a low risk for shoulder pain and swimmer’s shoulder, but these results may be individual, as no two people breathe alike.

10. Swimming training equipment

Paddles, kickboards, and other training equipment are often clumped together as causes of shoulder pain. However, only one of four studies found an association between training equipment and shoulder pain. Like most training variables, how one uses the equipment is causes individual differences and variations in shoulder stress and injury.

11. Cross training and stretching

Currently there is insufficient information regarding cross training and stretching and shoulder pain. Of the studies researched some found cross training and stretching increased shoulder injury and swimmer’s shoulder, but other studies found no association. Therefore, the implementation and use of cross training and stretching is likely a larger factor for swimmer’s shoulder than simply performing these activities. 

BRISBANE, AUSTRALIA - JULY 18: Eamon Sullivan poses during an Australian Swim team portrait session at Brisbane Aquatic Centre on July 18, 2010 in Brisbane, Australia. (Photo by Jonathan Wood/Getty Images)

12. Previous history of pain and injury

Three of the four research studies analyzing a previous history of pain and injury increased the risk of shoulder pain and swimmer’s shoulder. A study by Walker et al. found swimmers with a history of shoulder pain were 4.1 and 11.3 times more likely to sustain a subsequent injury for significant interfering pain in the shoulder and a significant shoulder injury, respectively. This study in combination of other research suggests a previous history of pain and injury is a risk factor for injury.

13. Sex

Differences between men and women are obvious, but the influence of sex on swimmer’s shoulder and pain isn’t well understood. Overall, the majority of studies found no association between sex and shoulder pain in swimmers, making sex a low risk factor of shoulder pain. 

14. Age

Age is often clumped with injuries (at least that’s what many often blame on aches and pains). However, nearly all the research studies found a no association between age and swimmer’s shoulder. 

15. Competitive level

Many differences exist between recreational and competitive swimmers. The obvious differences are volume and intensity, but even psychological factors are different. The research studies do suggest there is a moderate risk factor between shoulder pain and competitive level in swimmers. 

16. Shoulder blade (Scapular) kinematics (control), strength and dyskinesis

The shoulder blade is believed to contribute to shoulder pain and injury. However, only one study has found an association between these factors. This study had 20 swimmers with shoulder impingement and 20 healthy swimmers without history of shoulder pain and shoulder impingement was significantly associated with reduced strength during the scapular strength test after swimming.

However, two other studies did not find these variables as a risk factor for shoulder injury. Therefore the evidence for shoulder blade strength and control is low. However, the methods for measuring these factors is extremely different and perhaps the reason for the differences.

17. Core stability

There are only two studies that have analyzed the association between shoulder pain and core stability. One study found those with shoulder pain maintained a side plank for less time than a group without shoulder pain. However, a different study found the regular bridge was not associated with shoulder pain.

Once again, the methods and groups tested were different in these studies, therefore more research is needed and the risk factor of core stability requires more research. 

18. Pectoral length

Pectoral length has been correlated with shoulder pain in swimmers in two studies. In both of these studies, the pectoral length was shortened in those with shoulder pain, but the evidence for pectoral length and shoulder pain is low due to the research design of the studies. 

Conclusion

Overall, only a few of these risk factors have high certainty for shoulder pain in swimmers. This doesn’t mean some of these risk factors aren’t in fact risk factors, but may need more research or better research design, causing us to label these risks as low until we learn more.

Hill (2015) also noted the following as potential risk factors for shoulder pain and swimmer’s shoulder:

“swimming scholarship status, inadequate treatment, triceps length, latissimus length and internal/external rotation endurance.”

On top of this, individual biomechanics, anatomy (different people can have different bone size and position), and many other items can increase one’s risk of shoulder pain and swimmer’s shoulder. Ensure you are receiving an individualized plan for reducing your risk factors for swimmer’s shoulder from a physical therapist. If you have swimmer’s shoulder or shoulder pain, make sure you find a physical therapist with knowledge of these risk factors and work on reducing your shoulder pain. 

Reference:

    1. Hill L, Collins M, Posthumus M. Risk factors for shoulder pain and injury in swimmers: A critical systematic review. Phys Sportsmed. 2015 Sep 14:1-9. [Epub ahead of print]