Swimming is a intricate sport that places huge demands on the body for propelling through the water. The shoulders often suffer as a consequence of this, but, injury chiropractor, Dr. Alexander Jimenez asks, what are the implications of musculoskeletal shoulder asymmetry?
Overview
Swimming is a hugely popular game for both recreational and competitive functions. The nature of exercising against the water immunity provides a special setting compared to the field or court in all other sports. Likewise, most other sports utilize a dominant side, whereas in swimming that the repetitive, continuous motions require either side of your system to be coordinated and equally strong. This can place an accumulation of stress physically. The overhead actions of a swimming stroke may notably strain the shoulder joints and around 73% of swimmers will experience
shoulder pain at any stage within their career(1).
Taking this advice on board, surprisingly, swimmers do not usually develop symmetrically with equal muscle power on each side. And in which there is muscle imbalance, they commonly compensate by using different muscles more than ordinary to guarantee the total force generated is the same(2). Swimming also does not provide that point of contact or source to hold on to enjoy most other sports have. Swimmers rely on their inbuilt strength throughout the body along with the entire kinetic chain to generate maximum force propulsion. Expertise and strategy are important facets to contribute to this, however if there's a natural muscle imbalance then this can further affect technique, however much technique instruction you provide.
Asymmetry is defined when there's a muscle imbalance between the left and right sides greater than 10%(two). This means that the muscles on one side are more powerful or more efficient compared to those on the opposite side. A recent study that screened nationwide- level hens found that 85% were asymmetrical(two). Asymmetry usually develops because of the shoulder or whole arm being used wrongly or too often. Excessive repetition with no adequate rest causes the muscles to exhaustion. This decreases muscle activity and induce generation, and eventually causes biomechanical abnormalities as the swimmer attempts to overcome these failing mechanisms(3). A third of those swimmers in the study that were discovered with asymmetry were also identified as having compensatory plans(2). Asymmetry can lead to:
- further muscle imbalance;
- compensatory movement strategies, such as using increased hand force;
- muscle injury.
Every one of these can alter technique and thus performance execution. This might be the difference between finishing first and finishing second in competition.
Screening For Shoulder Asymmetry
Screening is the process of assessing a variety of characteristics that are significant with the game. This allows the identification of possible flaws and muscle imbalances. Strengthening applications to rectify such findings may provide optimum strength, functionality and prevention of injury.
Table 1 details the key screening tests for identifying asymmetry in shoulder power for swimming. This scale details if the athlete can move against gravity (tier 3), then resist your force (grade 4), and supply full strength to resist (grade 5).
Shoulder flexion is not listed here as a screening test as it's been found that it doesn't have any effect on shoulder asymmetry(2). This implies that many swimmers all have an equal stroke length. It seems to be the abduction, adduction and rotational components which become imbalanced and make the asymmetry of the shoulders.
Arm dominance and breathing side can also be often considered significant factors in procedure perfection; however studies have not found these to have any consequences on performance(two). For more technically precise ways to assess these functions with dynamometer, see the original research articles(1,2).
Even though these are significant testing purposes, it's just as important to look elsewhere when trying to identify potential weaknesses. The surrounding muscles like the latissimus dorsi should be considered.
Latissimus Dorsi Stiffness
The latissimus dorsi is your largest muscle of the trunk and is responsible for all pushing and pulling type activities. The repetitive character of swimming and thus overuse of the latissimus dorsi usually means that this muscle may be prone to stiffness.
Figure 2 shows the latissimus dorsi, which attaches to the mid spine at T7, the lower ribs and down to the pelvis at the iliac crest. It inserts into the top of the shoulder called the bicipital groove and also to the lower part of the shoulder blade. It inserts into the top of the shoulder called the bicipital groove and also to the lower part of the shoulder blade. It's these insertion points that allow the muscle to control shoulder blade motion.
A study that investigated the effects of latissimus dorsi stiffness on scapular movements among swimmers found that the muscle stiffness caused three significant problems with scapular mechanisms(1) (see Table 2).
Each of these issues alters the way the shoulder blade operates mechanically. This modified mechanics can then develop injuries as other structures become caught or pinched within the shoulder joint distances. These injuries will influence technique as the shoulder will slowly lose power and strength.
Have the athlete in crook lying with their back flat against the bed. Ask them to lift their arms over their head. If there is latissimus dorsi stiffness they'll struggle to fully stretch the arms overhead, and/or their spine will lift up away from the mattress.
For a more accurate and technical evaluation method refer to this analysis by Illinois University(1).
Power Exercises For Fat Loss
The added resistance that the water provides requires strengthening exercises to be carried out in similar motions to replicate the coils. This may improve the specificity and ensure the correct muscles have been targeted. Key exercises for scapular strengthening that carry over ideally for swimming are shown below.
1. Breaststroke
This is all about the scapular setting. The shoulder blades are activated as the arm extends forwards, then pull backwards just like the swimming stroke(10).
2. Swimming
The athlete raises their opposite arm and leg up while maintaining the shoulder blades in the neutral position. The opposite side is then performed(10).
3. Low row
Using a resistance band tied to a door handle in front, the athlete pulls the band backwards past their hip and slowly returns to the start position.
4. Front crawl simulation
This exercise involves having a resistance band from one hand around the back of the body and held in the other hand (like wearing a jacket). The affected arm is then taken through a front crawl stroke while pulling the resistance band tightly. The shoulder blades should be kept in neutral throughout and avoid the desire to throw the shoulder forwards.
Summary
- Asymmetry is a difference in muscle balance between the right and left sides and can lead to weakness, poor technique, compensatory strategies, and injury.
- Swimmers are susceptible to asymmetry due to the repetitive use of the shoulders. Specific screening tests can be performed to identify where weaknesses lie. Shoulder abduction, adduction, and rotations are the main culprits because of their repetitive use within every stroke.
- Treatment consists of strengthening and stabilizing the scapular muscles over a period of weeks, and making the exercises powerful to replicate the force required to battle through the water.
References: 1. Phys Ther in Sport. 2013; 14:50-53.
2. Phys Ther in Sport. 2013; http://dx.doi.org/ 10.1016/j.ptsp.2013.02.002
3. Rehab Res and Practice. 2012; ID:853037; 1-9.
4. McKesson Healthcare Solutions. 2004. www.mckesson.co.uk
5. Phys Ther in Sport. 2004; 3:109-124.
6. Musculoskeletal assessment. 2000. 2nd Ed; 150-156.
7. Clinical Sports Med. 2006. 3rd Ed; .246-247.
8. http://www.shoulderdoc.co.uk/article.asp?article=1381
9. http://www.youtube.com/watch?v=AcPZEtWP1x4 (2013).
10. APPI Pilates Matwork Handouts manual.2012. www.ausphysio.com
