Sports Podiatry is the treatment of foot, ankle, knee and leg injuries by altering lower limb function using a variety of methods, including orthotic insoles, footwear and exercises.
A podiatrist will analyse the way an individual’s foot strikes the ground and evaluate the chain of motion of the major joints in the leg from the ground up in order to determine whether or not there are any biomechanical reasons that may be contributing to an injury.
Biomechanics of running
The term ‘biomechanics’ refers to the way muscles, bones, and joints work together as we move. When applied to the lower limb, we focus on the biomechanics of impact absorption and propulsion.
The two terms used to describe the movements associated with the foot and ankle when running are ‘over pronation’ and ‘under pronation’ (supination), respectively.
Just after the heel strikes the ground when running the foot begins to pronate. Pronation is a movement that occurs as the weight of the runner moves from the lateral aspect (or outside) of the heel to the medial aspect (or inside) of the forefoot. This movement allows the foot and leg to adapt to the terrain and absorb the impact of the foot strike. A certain amount of pronation is necessary to run normally but too much or too little can contribute to injuries. Runners with low arches tend to “over-pronate”.
When the foot is in an over-pronated position the alignment of three major joints in the foot are less than optimal. This misalignment of the joints causes the foot to become structurally unstable, and, in turn, the muscles, tendons and ligaments of the lower leg are forced to work harder in an attempt to stabilise the foot. This is why over-pronators are vulnerable to ankle injuries. If you are a runner with a visibly low arch or have experienced recurrent or chronic overuse injuries, chances are you are pronating excessively.
The most common injuries that can affect over pronators are:
- Shin splints
- Plantar fasciitis
- Morton’s neuroma
- Achilles tendonitis
- Ankle sprains
- Knee injury
An under pronating foot is sometimes referred to as a “rigid lever” because it provides the firm base that pushes us forward after our heel leaves the ground and our weight shifts to the forefoot. A certain amount of rigidity is necessary to generate the force needed to run, but too much can decrease the foot’s ability to absorb impact and, therefore, can lead to impact-related injuries. Runners with high arches tend to ‘over-supinate’ or ‘under-pronate’. Runners with a supinated foot type may experience ankle pain. The most severe over supinators tend to have a history of recurrent ankle sprains and/or stress fractures. Runners who supinate excessively require the highest level of cushioning in their running shoes and should avoid shoes with stability features.
Some of the most common injuries that can affect under pronators are:
- Calf strain
- Plantar calcaneal bursitis
- Bone shin splints
- Calf strain
- ITB syndrome
- Hamstring strain
How do I know if I’m an over pronator or an under pronator?
The most common method a runner can use to determine what foot type they have is to stand on a paper towel with a wet foot. If your foot leaves an imprint of your entire foot, from heel to toe, you probably have a flat foot. If the imprint consists of the heel, the ball and a thin line connecting the two, you probably have a high-arched or supinated foot. This method is accurate if you have an extremely flat foot or an extremely high arch, but is not very accurate for those of us who fall somewhere in between.
For most of you, it is more accurate to evaluate your history of running or athletic injuries, and to combine that information with the paper towel test to determine what type of orthotics you need.
Remember that with some forms of biomechanical inefficiency, the feet may have a normal arch when standing or walking, but then over-pronate when the forces of running are encountered. So if your foot type looks normal but you are still getting repeated over pronation injuries, please consult your podiatrist.