I have been training many different individuals over the past few months. They all have different goals, needs, physical attributes, strengths and weaknesses. However, one thing in which they do not differ at all is that every single one of them has some form of muscular imbalance. In fact, everyone suffers from muscular imbalances to some extent and it can even affects athletes at the top of their game.

What is a Muscular Imbalance?
As the name suggests, muscular imbalances refers to when one muscle or muscle group is stronger, weaker or tighter than it’s opposing muscle or muscle group which can lead to limited movement, strength differences or dysfunction. Muscular imbalances can also been seen within the same muscle group on opposing sides of the body. For example, if an individual is dominant on the right side, the muscles on the right side may potentially be stronger than the muscles on the left side.

Agonist and Antagonist Muscles
An agonist is a muscle that causes movement to occur due to activation of that muscle. An antagonist is a muscle that assist this movement by producing opposing torque.

A good example of an agonist and antagonist is the action of both the biceps and triceps during a bicep curl. The two muscle work together – the biceps contacts to drive the weight upwards all whilst the triceps relax and length in order to control the movement. In this case the biceps are the agonists while the triceps are the antagonists.

Muscular Imbalance and Sport
Participating in regular sporting activities can contribute to development of muscular imbalances from dominant to non-dominant side which can affect recreational sports users all the way up to athletes.

A good example of this is 15-time Grand Slam winner, Rafa Nadal. You can clearly see the impact that tennis has had on both of his arms with his dominant arm (left) being a lot larger than his non-dominant arm (right).

Quite simply this is because he predominantly uses his left arm with every shot whereas his right arm is not subject to the same amount of force and movements as the right. As a result of the force and movements that the left arm is subject to on a regular basis, it has adapted and increased in size, strength and power.

Another couple of sporting examples where muscular imbalances can develop:
Football – Planted, standing leg when kicking the ball (often non-dominant leg) is subject to ground reaction force and also must stabilise the entire body effectively which can lead to imbalances between standing and kicking legs.
Athletics – Runners can be impacted by strength imbalances due to running round the track in the same direction.
Weightlifting – Overdevelopment of specific muscle groups and neglect of others can lead to postural issues.

What causes a Muscular Imbalance?
As covered in the above paragraph, repetition of the same action consistently can lead to imbalances in muscular size, strength and function. And being dominant on one side can also lead to muscular imbalances. You may not even notice that when you complete every day tasks (such as opening doors, lifting shopping bags, unlocking doors) you will, more often than not, do this using one side (your dominant side) which over time, can cause very slight differences.

Sitting for prolonged periods of time can lead to lengthening and weakening of musculature. A common area which affects many is the musculature of the back and chest.  The trapezius, rhomboids and latissimus dorsi can become lengthened and weaker whilst the pectoralis major and minor can become tight. This combination can cause the head to move into a forward position.

Previous injury and inadequate rehabilitation is potentially one of the biggest causes of muscular imbalance. The structures that are damaged as a result of injury do not fully restore to the same strength and function that they had prior to injury. This is why adequate rehab is essential as if rehab is not adequate, these structures will not restrengthen and an imbalance will remain between the affected site and the opposing muscle or muscle groups.

Training to improve Muscular balance
Regular stretching is very important in order to restore muscular balance. Any restrictions that may be present within the muscles need to be alleviated in order to restore full function. This can be done with use of foam rollers, static holds and resistance bands.

Guidelines for Strength Training
Similarly, if a strength imbalance exists then this needs to be corrected.

Focus on Unilateral exercises
Unilateral exercises use one limb at a time. Bilateral movements (two limbs at the same time) can often mask muscular imbalances as one side can compensate for the weaker side. For example, in an overhead press, if the right side is the dominant side, more force may be generated from the right shoulder than the left shoulder in order to raise the bar over the head and therefore any strength imbalance that exists will not be resolved – infact, the imbalance may even widen.

Always start with the weak side first
The amount of reps completed by the weak side dictates how many reps should be completed on the dominant side (even if the dominant side could complete more). For example, lets say with bicep curl, the non-dominant weaker side completes 6 reps at 10kg, the dominant right side should then also complete 6 reps at 10kg. If this principle isn’t applied the strong side will continue to become stronger which will not allow the weak side to reach the same level. Understand that unfortunately, the dominant side may become a little weaker over time as it does not have to work to it’s maximum, however, this is just part of the process of evening out the imbalance.

Additional sets for the weak side
To assist further in allowing the weaker side to catch up, additional sets can be completed for the weak side. So lets say, again for bicep curl, 2 sets of 6 reps for the dominant right side and 4 sets of 6 reps for the non-dominant left side.

Regularly assess
Ensure you assess the imbalance regularly so that you know when the weaker side has caught up with the stronger side.