Overpronation.

Overpronation is one of the most frequently used terms I hear in fitness. This is from both trainers and clients. The plethora of pronation control shoes has plucked the word from the world of anatomy and physiology and biomechanics into everyday terminology.

Although the word is widely used it is not widely understood. Overpronation can happen in many ways and for multiple reasons but is generally used as a generic term and no more attention is paid to it.

Lets first define pronation. It is the triplane action of dorsiflexion, eversion and abduction at the rearfoot.  These joint motions are relative to the bone motion of the talus which is the primary moving bone in a closed chain scenario. This rearfoot motion will also create relative forefoot dorsiflexion, inversion and abduction. The forefoot can have quite an impact on rearfoot pronation that we will talk about later in the blog!

Now lets look at the different ways in which we can overpronate.

1. Range-I think this is the “classic” definition of overpronation. The amount of distance that the joint goes through. Obviously far too much range places stress on the joint and muscles all through the kinetic chain of the lower limb. The associated tissues have to work hard to control the excess range. Common problems that can arise are posterior tibialis syndromes, Achilles problems and ITB problems.

2. Rate-Along with range goes the rate or speed/acceleration of pronation. The larger the range, the more distance to accelerate into. This again causes problems for the muscles/tissues that have to decelerate this increased acceleration.

3.Sequence-This is the most overlooked element of overpronation. Pronation should occur at initial heel strike and be followed by supination. If the range and rate are excessive then the foot is unable to reverse the motion in time to go into supination. This means that someone may pronate through midstance and also through the propulsive phase of gait. If any of the motions associated with supination are restricted it may also lead to a return to pronation late in the gait sequence.This can also be because of the instability created by the pathomechanics of different foot types. This can lead to plantar fascia problems and HAV bunions as the foot remains in its unlocked mobile state rather than becoming the rigid propulsive unit that the supination process creates.

The question most often overlooked when it comes to pronation problems is WHY??           A good knowledge of foot dysfunction is required to really answer this question. The most overlooked area in my opinion that causes pronation problems is ontogenic (developmental) forefoot positioning relative to the rearfoot. However I am also really interested in the spatial location of the STJ (subtalar joint) axis. The medial  deviation of the STJ will increase the moment arm of GRF (ground reaction forces) associated with pronation and decrease the moment arm of the supinatory muscles. It will also increase the area of the foot laterally to the STJ that  cause pronation to happen when force is applied. The lateral deviation will do the opposite with more internal muscular supinatory force and decreased GRF pronatory force occurring and increased medial area of the foot that will cause supination.

Anyway, back to the forefoot!! An inverted or varused forefoot position will be compensated for at the rearfoot by excess pronation. Another scenario is that the foot is able to get into supination but the extra instability of the varused forefoot causes a pronation response to get the forefoot on the ground and create stability. This would happen late and out of sequence in the gait cycle. This means that just controlling the longitudinal arch as many pronation control shoes do, does not gain quite the control anticipated.

Many times I also see short or half foot orthotics. These orthoses have arch control but do not provide stability at the forefoot. This is done by bringing the ground up to the foot, to stop the foot trying to search out the ground. Without the forefoot control I see the foot unable to pronate to compensate because of the arch control, instead using the transverse plane to rotate the foot and tip onto the forefoot. This maybe a reason behind a medial heel whip!! A similar thing can happen when the STJ axis height is high and favours transverse plane motion over frontal. The STJ axis height should be around 42 degrees from the transverse plane, slightly favouring frontal plane motion.

I realise this a bit of a big post, but is also a really big subject. Much more complicated than many give it credit for, so thanks for reading. Until next time….

Ben Cormack

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3 Responses to Overpronation.

  1. Hi Ben
    Great stuff as usual…
    Have you done one on a Tailor’s bunion yet?
    Best regards,
    Robert Werner

  2. Michael says:

    When you say forefoot control? Would you refer to varus wedging to accommodate a varus (fixed inverted position of forefoot)? Perhaps forefoot inverted position is inverted due to soft tissue adaptation? Adding a varus wedge in walking gait may Inc GRF sub 1st mpj, thus Inc force required to activate windlass mechanism and delay windlass effect, thus in turn lead to dec supination effect??? Refer to hicks windlass mechanism articles in 1970’s….. I can see use for varus wedging in forefoot to shift centre of pressure medial to stj axis in running gait, due to windlass effect not as important in run gait, this varus wedge in forefoot would dec valgus bending of tibia and tensile stress on structures that run/insert medial to stj axis!

    • bencormackpt says:

      Michael. Thanks for your comment. Absolutely the FF positioning could be due to soft tissue adaptation. Almost all structural issues will also have some soft tissue adaptation. A supinatus would obviously have a different end feel than a more bony restriction. Supination starts to happen way before toe off (in fact in mid stance) when the windlass mechanism works most (hallux dorsi flex). The external rotation of the tibia inverts the STJ relatively everting the FF. However if the inverted positioning means the FF’s medial side is off the floor and unable to relatively evert then a compensatory response is to pronate the STJ when it should be supinating. This would be a sequencing issue as I discussed in the blog. With a bar post bringing the floor to the foot the foot is no longer unbalanced meaning no need for compensatory pronation response from the STJ. We tend to use this thought process with RF wedging but I feel is no different at the FF. The pronatory response tends to be later with a FF abnormality. Arch control many times does not control compensation for FF problems generally causing other compensations such as a medial heel whip. With a FF Varus that is rigid we will probably see a limited hallux anyway that will compromise the windlass mechanism. The windlass mechanism is important but the foot can still supinate without hallux dorsi flexion. Try standing and rotating your arms over the foot. E.G Right foot/right rotation of the arms. This will create an arch in the foot. If not then you may need some kind of wedge as your foot is choosing not to supinate for stability reasons as the FF is inverting with the RF due to limited eversion.

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