Many attempts have been made to clarify the three-dimensional motion that occurs in the foot upon contact with the ground that causes shin splints. 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 lower limb shin splints, we focus on the biomechanics of impact absorbtion and propulsion.
The two terms used to describe the movements associated with these are pronation and supination, respectively.Both foot types may cause shin splints. Pronation may cause muscular shin splints and supination may cause boney shin splints.
Shin splints- Pronation
Just after the heel strikes the ground the foot begins to pronate. Pronation is a movement that occurs as the we
ight 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 walk and 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-pronaters are vulnerable to plantar fasciitis (heel pain), shin splints, achilles tendonitis, iliotibial band syndrome, knee pain and other overuse 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.
Shin splints- Supination
Just after the foot has absorbed impact, the forefoot contacts the ground and supi
nation begins. A supinated 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. A certain amount of supination 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 boney shin splints. 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 on the the things to look out for when purchasing a new pair of trainers
How do I know if I'm an "over-pronator" or an "over-supinator"?
The most common method to determine your foot type 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 absorbancy problems or think you have boney shin splints then you may supinate (rare).If you're still just not sure what type of foot you consult our practice at www.sportspodiatry.co.uk.
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 istelf cause an otherwise biomechanically normal individual to over pronate when running. So if your foot type looks normal but you are still gettting repeated over pronation injuries then we advise undertaking an initial consultation.
