What is supination resistance of the foot?

The foot is a masterpiece of design. Each foot has 26 bones, 100’s of ligaments, muscles and tendons. All of these components need to function with each other in a very precise way to ensure that we are able to walk, run and carry out a whole variety of actions. The foot is a finely tuned biomechanical masterpiece of design as it needs to co-ordinate all of the physiological structures so that it can function properly and without problems to undertake those actions. The foot did evolve to get those characteristics on a soft surface and not wearing shoes, so a number of defects probably crept in as feet was placed into shoes and was forced to walk and run on the hard concrete surfaces. Small imperfections that were not previously an issue did start to show up in those shoes and on those hard ground. It is this that is to blame for so many of the conditions that health professionals see in the foot nowadays.

For instance, one of those problems is a theory known as supination resistance. This is deemed as the force that's needed to raise the arch of the foot. If that force is high, then the muscles and tendons need to work harder and the ligaments have more strain on them. This might lead to pain in those structures and the development of a progressive flat foot. If this force is higher, walking and running also requires more energy and could be very tireing. If that supination resistance force is too low, then it will likely be very easy to raise the arch of the foot. This can result in more ankle sprains because it is so easy to tip the foot over to cause that. From this it should be clear that a fine balance is necessary between too much and too low amounts of force which is a great illustration of just what an engineering miracle the foot is and just how simple it is for something to go bad.

How important are the small muscles in the foot?

There are many small muscles under the bottom of the foot and probably because of their size they have not been given much importance. This has started to change recently has research has begun to show just how important those muscles are to normal function and biomechanics of the foot. They appear to play an important roll in how we balance and problems with these small muscles is probably a factor in most of the toe deformities. This topic was addressed in a recent episode of the podiatry chat show that goes out live on Facebook called PodChatLive. In that episode the hosts talked with Luke Kelly who has published extensively in the field of plantar intrinsic foot muscle function and just how important they are. He talked about the spring-like function of the human foot when walking and the role of those muscles in that. He also talked about why it is false to assume a flatter foot is a “weaker” foot. He also explains why he is personally not a fan of the ‘short foot exercise’ and just why strengthening the intrinsic muscles will never make the medial longitudinal arch ‘higher’ which is widely believed myth.

Dr Luke Kelly PhD has over fifteen years of clinical experience helping people with pain due to musculoskeletal injury and chronic health conditions. He has completed a PhD in biomechanics and is actively involved in research that attempts to improve our understanding and management of common foot conditions, such as plantar heel pain, foot tendon injuries, osteoarthritis in the foot and children’s sporting injuries. He currently is a Senior Research Fellow within the Centre for Sensorimotor Performance in the School of Human Movement & Nutrition Sciences at the University of Queensland in Australia. Luke’s current research is examining how the brain and spinal cord integrates sensory feedback to adapt the mechanical function of the foot during walking.