The science of pronation

This week we're very lucky to have the wise words of fellow Physio James Cruickshank as our guest blogger…

This whole world is new to me. I was introduced to the ‘blogging’ thanks to reading some interesting and well written pieces by Tom, the owner of this blog. The articles he writes combine literature expertise with clinical knowledge, providing information both easy to understand and practical. When Tom asked me to provide information for his blog, I didn’t know why or what to write, but I was very excited to be involved.

So who am I? I trained in Aberdeen completing both my BSc in Sports and Exercise science and then my MSc in Physiotherapy. Previously I had dreams of playing football professionally, until it was curtailed by a serious leg break…..which was later to pave my career path into sports rehabilitation. I have a fantastic enthusiasm for rehabilitation, for getting people back to what they love. There is no better feeling than getting someone to run a PB, swim a length in a pool or bowl an end of lawn bowls……or even put on a pair of socks on their own.


I currently work for the NHS in Grampian, specialising in MSK (muscle and bone injuries) rehabilitation and also for a private hospital. Outwith work, I love the outdoors……if it involves adrenaline, slopes, gadgets, risk, weather and my buddies, I am there. I board, I climb, I ride, I run, I swim (not very well), I golf, I fish………..I can offer advice, hints tips on any of these areas but more importantly I love to hear what other people are thinking about all these sports so if you get a second follow me so I can read your point of view (@cruicky_05).


So enough of the shameless plug and back to the mighty job in hand…..keeping up to Tom’s High standards…The latest debate that I was interested in was one on over pronation and should we correct it, so I thought I would do a little bit of an article on this……these are my own points of view and opinions so direct questions and debates towards me, I love answering questions……



Addressing and Correcting Overpronation to Decrease Joint Stress


We all know that the foot and ankle complex is extremely important to the overall function of the human body because it is the only structure that interacts with the ground while in an upright position. The foot and ankle complex is directly responsible for the distribution of weight and pressure throughout the body when the forces of kinetic energy, gravity and the ground collide (still can’t say that word out loud without thinking how Matt Cardle murdered a beautiful BiffyClyro song). Therefore, it is imperative that the foot and ankle complex is fully functional and doing its job correctly to ensure that the force of gravity is properly dissipated throughout the rest of the body.



Common Problems in the foot and Ankle Complex


One of the main postural deviations that cause pain and injury in the foot and ankle area (and resultant compensations in the rest of the body) is overpronation.

Pronation is a normal function that occurs when the foot rolls inward toward the midline of the body. This movement causes the heel to collapse inward and the medial arch of the foot to elongate and flatten. Overpronation, however, is when the foot collapses too far inward for normal function.Consequently, this directly affects the ability of the foot to perform and can disrupt proper functioning through the entire body.

In addition to problems overpronation causes in the feet, it can also create issues in the calf muscles and lower legs. The calf muscles, which attach to the heel via the Achilles tendon, can become twisted and irritated as a result of the heel rolling excessively toward the midline of the body. Over time this can lead to inflexibility of the calf muscles and the Achilles tendon, which will likely lead to another common problems in the foot and ankle complex, the inability to dorsiflex. As such, overpronation is intrinsically linked to the inability to dorsiflex.


Pronation is Good, Overpronation is Not


The foot and ankle complex needs to pronate to make the muscles of the hips and legs work correctly. Many muscles that originate from the pelvis attach to both the upper and lower leg. For example, the gluteus maximus and tensor fascialatae (TFL) attach to the outside of the lower leg via the iliotibial band, while the abductors attach to the outside of the femur. When the foot pronates, the whole leg rotates inward toward the center line of the body. This inward rotation pulls the attachment of the glutes, TFL and abductors away from the origin of these muscles up on the pelvis which creates tension. Similarly, the muscles of the lower leg such as the peroneals, tibialis anterior and tibialis posterior originate on the lower leg and attach to the underside of the foot. When the foot flattens out, as it does in pronation, this pulls the insertion of these muscles away from their origin on the tibia. This action also creates tension in the muscles.


To better understand how the muscles and tissue structures in the feet, ankles, legs and hips are adversely affected by overpronation, imagine a person on the end of a bungee cord jumping off a bridge. If the bungee cord gets the right amount of tension on it as the person nears the ground, then he/she will be saved from smashing into the earth. However, if the bungee cord does not pull tight because it is twisted or has no elasticity, then the person will impact the ground with dire consequences (I love the outdoors, but wouldn’t wish to be that close to it J). The muscles, tendons, ligaments, and fascia of the legs and feet are the body's bungee cords. If these bungee cords work together, they can protect the joints of the feet and ankles from excessive stress, and prevent muscle and tissue damage caused by overpronation. If they do not work properly, a person will be able to see evidence of this in the feet and ankles, particularly in the alignment of the joints.


In addition to controlling forces down through the joints, the body's muscular “bungee cord system” also stores energy that can be used to create strong, powerful movements as this energy is released, much like the forward propulsion of the legs when walking. However, if a person overpronates, the energy stored in the “bungee cord system” is lost, preventing the body from taking mechanical advantage of stored energy in the muscles.


The Big Toe Breaking Mechanism


When weight is transferred correctly through the foot and ankle, the foot should strike the ground on the outside of the heel. Then, the foot and ankle should pronate to load the muscle “bungee cords” and create a powerful release that enables the foot to supinate and transfer weight over the front of the toes. When a person overpronates, however, their body weight continues to collapse toward the midline of the body. So instead of supinating and using the lesser toes to transfer and dissipate forces, the full weight of the body passes through the first joint of the big toe. This is why bunions and calluses are located on the inside border of the foot. They are usually caused by chronic overpronation.


Fortunately, the big toe can act as a break to stop the foot from collapsing too far inward (overpronating). If muscles are used to pull the big toe down into the ground, it creates tension in the arch of the foot and prevents the foot from overpronating. However, people that overpronate have other muscles of the lower kinetic chain that are weak. So, it will be necessary to address the muscles of the big toe in combination with other dynamic exercises to keep the muscle “bungee cord system” fully functional and working together as it should. (so the twitter trend by @AdamMeakins where he suggested we include the assessment and treatment of the large toe is founded and should be included in all lower limb biomechanical assessments. The second point, should we correct over pronation, I believe will be answered in my piece.)


Visual Assessments for the Foot and Ankle


To easily get an idea of whether a person overpronates, look at the position and condition of certain structures in the feet and ankles when he/she stands still. When performing weight-bearing activities like walking or running, muscles and other soft tissue structures work to control gravity's effect and ground reaction forces to the joints. If the muscles of the leg, pelvis, and feet are working correctly, then the joints in these areas such as the knees, hips, and ankles will experience less stress. However, if the muscles and other soft tissues are not working efficiently, then structural changes and clues in the feet are visible and indicate habitual overpronation.


The following clues indicate overpronation:

My favourite toy, I mentioned I like gadgets, is to be the BOSU trainer. I use it in my training and incorporate it into so many rehabilitation programmes. It is a wonderful piece of kit so if you don’t have one get one, if you don’t use it use it!!!!!!!! Lecture over!


Using the BOSU Balance Trainer to address Overpronation


The soft, dynamic surface of the BOSU Balance Trainer dome surface is ideal for training the foot and ankle complex to load into pronation without collapsing into overpronation. For beginners, the dome can be inflated so that the surface has less movement. Alternatively, deflating the BOSU allows the foot to move more dynamically, creating an even greater challenge of trying to avoid overpronation when performing the following exercises.


Exercises (pictures courtesy of BOSU.com)
The following exercises help retrain the foot and ankle complex to correct overpronation. Exercises may be performed while wearing shoes, or for an even greater challenge, in bare feet.

Conclusion


So is overpronation good, bad or indifferent? IMHO (getting down with the lingo now) I feel that yes there is a degree of overpronation secondary to our lifestyle etc, but I do feel that to optimise strength, explosive power, endurance and basically anything to do with characteristics required to perform sport I think it should be assessed. With the everyday recreational runner, looking to complete 5km 10km runs I would focus on the biomechanical make up that prevents injury and ensuring footwear supports, gastrocnemius and soleus and the rest are at a length that allows optimal shock absorbing…..but fortunately our minds get tested further, when the elite athlete comes in….should we treat over pronation? is it beneficial to change the bottom of the chain and risk putting the rest out of sync…..it’s true ”if it’s not broke don’t fix it” or “if you change nothing, nothing changes” but surely if elite athletes are pushing for changes to the level of 0.01s then I believe that if you don’t recruit all the “bungee’s” potential you won’t achieve these marginal improvements……it’s not life or death but could be “gold” or “silver” which is worth a lot more……………………………….

Thanks for reading, hope its ok and makes sense, if not at least it filled my day off work….four days till I get to the big 3-0 and filling my days off getting excited about big toes….it doesn’t get any better J!


Pea Suit


James