Sports podiatry biomechanics

Biomechanics of running

Many attempts have been made to clarify the three-dimensional motion that occurs in the foot upon contact with the ground when running. Despite this, there is still a tremendous amount of confusion about how the foot and leg function together and how their movement affects our running.

The term biomechanics refers to the way our 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.

Video of running gait cycle

In the basic gait cycle the movements are divided into the times when the foot is on the ground (the stance phase which takes up 62% of the full gait cycle) and when the foot is off the ground (the swing phase which takes up the remaining 38% of one full gait cycle).

the gait cycle

The stance phase of gait can divided into

  • Heel strike
  • Midtsance
  • Toe off

The planes of motion of the foot explained

This video will give the athlete more of an understanding of the planes of motion within the foot when partaking in activity.

Biomechanics of the foot and ankle when running

The two terms used to describe the movements associated with the foot and ankle when running are pronation and under pronation (supination), respectively.

Over Pronation

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 footstrike. 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.

video of over pronation whilst running

The most common injuries that can affect over pronators are;

foot injuries

Plantar fasciitis

Morton’s neuroma

Achilles tendonitis

Ankle sprains

Knee injury

Over pronation can be helped with motion control trainers

Over pronation, when identified can be a serious problem for the athlete. Luckily our clinicians are experienced in this mechanical problem and understand that one of the best things an athlete can do is to purchase motion control trainers.

Under pronation

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 in the toe off phase of gait. This is usually quite an efficient lever for running. 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. See our running shoe guide for more information.

video of under pronation whilst running

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

Shock absorbing trainers are the best for under pronators

Our clinicians see many patients with a rigid or under pronating foot type. Whilst this is generally the best of the foot types to have, due to its rigid nature, shock absorbency is poor. Therefore we recommend trainers with as much shock absorbency as possible. Luckily the leading manufacturers provide excellent shock absorbing running shoes.

How do I know if I’m an over-pronator or an Under-pronator?

This is an excellent video showing the different foot types.

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. If you have had a long history of knee pain, iliotibial band syndrome, plantar fasciitis, Achilles tendonitis, or shin splints, you may over-pronate. If you suffer from continued shock absorbency problems then you may have a neutral/ rigid foot type.

Please 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. This is due to the fact that runners plant their feet on the midline of their body when at speed, this will itself cause an otherwise biomechanically normal individual to over pronate when running. So if your foot type looks normal but you are still getting repeated over pronation injuries then we advise getting a professional opinion.

Visit our sports podiatry clinic pages for a clinic near you.