Muscle Imbalance and Injury Risk – Tips for Physiotherapists and Personal Trainers

Many people looking to get fit end up with injuries, and it is a sad fact that many of these injuries can be prevented by looking more closely at how the exercise programs are structured and how they effectively balance all the muscles of the body.

Muscle balance can be defined as the “relationship between both the strength and the length of muscles and groups of muscles as they cross over joints “. This definition leads us to the conclusion that it is possible for muscles to have any or a combination of the following :

a)    increased tightness leading to a reduction in joint motion and stiffness

b)    decreased tightness leading to a increase in joint motion and instability

c)    increased muscle strength leading to internal joint position issues

d)    decreased muscle strength leading to poor joint control

Muscle imbalances are also seen between the larger outer muscles that control major movement of a joint and the smaller internal muscles that are more responsible for deep stability and control – as in your case – the shoulder. Like many joints in the body the shoulder has a complex inter-relationship between these internal and external muscles that can lead to problems if these relationships become unbalanced.

The small internal muscles of the shoulder – often referred to as “the inner sleeve” include the well known rotator cuff group comprising the Supraspinatus, Infraspinatus, Subscapularis and the Teres Minor – these small but important muscles arise from the scapula (shoulder blade) and insert into the humerus ( arm bone) and essentially keep the humerus in close contact with the scapula and have a role in rotation of the humerus – thus the name – rotator cuff.

In contrast to these small muscles there are many larger muscles that cross the shoulder – these are called the “outer sleeve” and include the powerful Latissimus Dorsi, Pectoralis Major and Deltoids – amongst others. These large and powerful muscles are often worked hard in may resistance training programs and sporting activities however , as may be the case in your shoulder, these large outer sleeve muscles dominate their smaller “ inner sleeve” counterparts leading to fatigue, pain and eventual muscle failure.

Looking at the design of many resistance training programs it is easy to see how muscles imbalances such as these occur – the average gym user wants to gain maximal aesthetic value from their training and will focus on the larger chest, back and shoulder areas – often on consecutive days – without ever realising how overloaded their small support muscles are and how close these muscles may be to failure.

It is vital that all health enthusiasts appreciate that fitness is not all about training the larger muscles and having a great set of “pecs and delts” – effective training is about balancing your body with a variety of exercises and movements that focus equal attention to the smaller stability muscles as is placed on the larger and more obvious muscle groups.

Remember – if you are at all concerned about individual muscle imbalance issues see your Physiotherapist or Personal Trainer BEFORE symptoms appear.

Tips on Avoiding Muscle Imbalances

–          Include same balance and stability training in every workout such as Busu and Fitball

–          It is common to have a slight strength difference Right to Left – however attempt to reduce this deficit by performing single limb exercises such as lunges and standing one arm cable rows

–          Use a variety of equipment including cables, dumbbells and not just machine systems

–          Athletes need to pay close attention to the opposite muscles to those used in their sport – to ensure overall body balance is maintained.

–          Balance your exercises by doing exact opposites movements – eg balance your Bench Press with Bent Over Rows, and your Military press with your Chins and Pulldowns.

You can get full acces to more than 50 hours of exercise rehabilitation and injury prevention videos at

Paul Wright

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