Ankle mobility and landing mechanics
Football is a sport with a high incidence of knee injuries. Among them, the anterior cruciate ligament (ACL) rupture occurs frequently. ACL injury can lead to significant time off the field for players as they undergo months of rehabilitation and training before being cleared to compete again. Several risk factors have been associated with ACL tears, with a particular emphasis on aspects related to thigh muscle strength, hip and trunk stability, and the player’s ability to stabilise their lower limb during movements such as landings and changes of direction. However, ankle dorsiflexion limitations are often overlooked as a risk factor, but they can profoundly impact the mechanics of movement in the entire lower limb, including muscle activation and even the positioning of the trunk. In this article, we will show why it is essential to ensure that our team players have optimal ankle mobility and use correct motor control strategies during landing.
Research has identified two biomechanical patterns associated with knee injuries: dynamic valgus of the lower limb and limited knee flexion. (Taylor, et al., 2021)(Figure 1). Although it may not seem like it, ankle dorsiflexion largely determines the outcome of these two movement patterns.
Figure 1. Knee valgus (Left), restricted knee flexion during landing (Middle) and unrestricted knee flexion during landing (Right).
When ankle dorsiflexion movement is restricted, the ability to flex the knee during landing is limited since knee flexion must be accompanied by ankle dorsiflexion and hip flexion to maintain balance. Otherwise, the body’s center of gravity would shift backwards, and we would lose our balance and fall backwards. This lack of lower limb flexion will lead to stiffer landing techniques and changes of direction, increasing ground reaction forces (Mason-Mackay, et al., 2017) and the load on the lower limb joints (Ivana Hanzlíková, et al., 2022), especially the knee and lower back (ankle mobility deficits are usually compensated by excessive forward lean).
In addition, this stiffness and lack of flexion of the lower limb during landings is also associated with compensatory movements that increase the risk of injury. Lack of ankle dorsiflexion has been associated with increased foot and ankle pronation, greater knee abduction, and increased hip adduction (Taylor, et al., 2021)(Figure 2).
These compensatory movements cause the knee to be displaced medially (known as knee valgus), increasing the chances of sustaining ACL injuries.
Figure 2. Flexed landing (Left) vs stiff landing (Right)
Great blog Raul! Clear to see your thoughts on the kinetic chain and the influence of ankle dorsiflexion. Looking forward to your next blogs!