Injury Prevention in Young Elite Footballers | Part 3: Leg Asymmetry
Updated: Sep 20, 2021
Have you ever thought about which leg is your dominant leg? Whether you are left foot dominant like Messi or right foot dominant like Ronaldo, there may be more meaning behind the relationship between your preferred and non-preferred leg in terms of injury on the soccer field. This blog discusses the evidence behind potential injury mechanisms between the preferred vs, non-preferred leg as a continuation of the injury prevention in young elite footballers series.
Which one is my dominant leg?
It has always been hard to determine what can be clearly defined as the dominant leg, for a lot of people some tasks like single-leg balancing may be easier on one leg but when kicking a soccer ball, it may be easier on the opposite leg.
However, let's say your dominant leg (or preferred leg) is the leg that is used to lead in movement such as running or used primarily to manipulate an object (dribbling or kicking a soccer ball). Whilst the non-dominant leg (non-preferred leg) should be defined as the leg used for stabilising or supporting.
What are and how are asymmetries/disbalances measured?
Asymmetry of the lower limbs can come in many forms asymmetry: it can be the difference in muscle strength between the two legs, difference in range or difference in control/balance. All of these are potential factors that may cause the body to react and adapt to enable you to function “normally” on the sports field or day-to-day activities.
To measure asymmetry between the two legs usually a whole range of different tests are done. These tests include range of motion of the leg/flexibility, strength, and other functional movements such as kick/kicking velocity, balance, single leg squat etc.
The most common method of measurement for muscle strength between the two legs is the usage of an isokinetic dynamometer (see our previous blog for more information). This involves measuring the muscle groups of the leg when it is both concentrically and eccentrically contracting and at varying velocity of movement.
Asymmetries and the connection to injury
Does asymmetry between the dominant and non-dominant leg lead to a higher risk of injury in soccer? There is a general consensus that in youth soccer players there is generally a lower body imbalance, especially in activation and motor control of lower limb muscles. Such imbalances may predispose players to injury and there has been evidence to suggest that there is a correlation in higher rates of ACL injury in soccer athletes in their dominant leg. This is also on the background that soccer players tend to have a general imbalance in hamstring leg strength between their dominant and non-dominant leg.
How to prevent injury?
In conclusion, it is acceptable to have a slight imbalance between your dominant and non-dominant leg. You are at a higher chance of being at risk from other factors such as playing time, intensity of playing and contact with opponent than you are of a slight imbalance issue. If there is a massive difference in function or strength of your two legs, then there will be a higher risk of injury. There is not enough evidence to conclude what is the ratio of discrepancy between the two legs should be.
The general recommendation would be to continue with general strengthening training especially in the hamstrings and doing more functional activities like squats and jumps as well as training the use of soccer drills such as dribbling with your non-dominant leg. It would also be good to add in more motor control training as shown in this video: single leg squat on bosu ball
To end this blog, we'll also talk about leg length discrepancy. Most people have a difference of approximately 1cm between their two legs. This does not generally affect their day-to-day actives or cause an increased risk of injury while playing soccer. It is only when this discrepancy becomes significant that there might be an increased risk of injury as how you walk, and run would be affected. Overall, if there is not a noticeable leg length discrepancy there would be not much to worry about. If you feel that the difference of your leg length is causing you trouble with walking or cause you discomfort, it would be good to discuss this with your physiotherapist or obtain a referral to see a sports physician for further investigation and opinion.
Blog and videos by UQ Physiotherapy student undertaking clinical placement, supervised by principal physiotherapist, Winnie Lu.
Winnie Lu, B.Phty (Uni of Qld)
Souths United Football Club Physiotherapist
Book an appointment with Winnie here.
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Atkins, S. J., Bentley, I., Hurst, H. T., Sinclair, J. K., & Hesketh, C. (2016). The Presence of Bilateral Imbalance of the Lower Limbs in Elite Youth Soccer Players of Different Ages. Journal of Strength and Conditioning Research, 30(4), 1007–1013.
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