Welcome to the Mike Varney Physiotherapy News and Advice blog

Running Biomechanics

Running shoes have a limited life. A pair of top end running shoes such as asics will only last for 400-500miles. This will however, vary depending primarily on your running surface for example; track, road, treadmill or trail path. Mileage lifespan of trainers refers to the foam that runs through the middle and sole of the shoe, this unfortunately is the quickest wearing part of the shoe as it takes all the impact from the ground and your body weight.

How do I know if it’s the right fit?

It’s important to not solely trust the manufactures sizing, as they are all different and there is in fact no standard shoe size. The best way to test the right fit is to stand up with your shoes on and bend your toes up towards your shin. There should be a gap of a finger width between your longest toe and the end of the trainer. The laces should be tied tightly but comfortable. Loose laces mean the middle of the foot will not be held properly, allowing the foot to rotate, pronate and supinate.

Pronate? Supinate? Neutral?

Every runner’s foot biomechanics is different but trainer manufacturers rely on three terms: Pronation, Supination and Neutral. These terms refer to the different position of the foot when running and the way the foot rolls in the shoe when contacting and leaving the ground. The picture below shows the different foot positions in running biomechanics.

  • Pronation refers to the inward roll of the foot during normal motion and occurs as the outer edge of the heel strikes the ground and the foot rolls inward and flattens out.
  • Supination is the opposite of pronation and refers to the outward roll of the foot during normal motion.
  • Neutral foot positioning is rare but it means that the foot has the normal roll without excessive movement in either direction.


What can I do to adjust this?

Choosing the right shoes is important. You want a trainer that suites your running gait or foot type. Most running shops will give you a gait analysis when buying trainers, this usually consists of running on a treadmill and videoing your heels from the back to identify which direction the foot is rolling. Top level running trainers come in different models to correct pronation and supination, however you do not want to just rely on the shoes to correct your running biomechanics. Money spent at the podiatrist or physiotherapists now, for a complete foot-strike, orthotic fitting and running gait analysis, will save you much heart-ache and discomfort later. Having the correct shoes will prevent pain and injury when your post 10 miles down the road.

How close to a marathon should I replace my trainers?

According to the running blog: marathondessables.co.uk, your trainers should be worn in enough that you feel comfortable, but not too much that you have started to compromise the protection they could be providing. Make sure you do not run in brand new trainers on the day, as this will increase the risk of injury and serious blisters. Most runners will need to have completed 50-60 miles in new trainers to ensure that they are happy with the comfort and biomechanics.

To increase the life expectancy of your trainers, you should ideally give them a day off between runs to allow the material to bounce back to the original state. If you run on consecutive days, it’s worth having two pairs of trainers, to guarantee you have adequate show protection and performance.


Should you find that your getting pain whilst running, Mike Varney Physiotherapy offer gait analysis and orthotic fitting as part of our treatment sessions. To find out more about the orthotics we offer please visit our products page or our orthotics guide. To book in for a gait analysis please phone 01279 414959.

  Related Posts
Call Now Button