Pain behind the base of the big toe when I ride - What is it and how can I fix it?

The vast majority of foot pressure when pedalling tends to come from under the base of the ball of the foot behind the big toe.  We’ll call this area PMA 1 (Plantar Metatarsal Area 1) for convenience.  Studies vary but the value of the load in this region is around 60% of the whole foot total.  This is a huge amount when you factor in the repetitive nature of pedalling.  Most of us can tolerate this pressure with little to no pain.  There is a small portion of the cycling population who suffer from mild to severe pain in this region.  Why is this and how can we help?

As usual with feet, getting to the bottom of the problem isn’t necessarily straight forward.  There are many reasons as to why this may occur and as a consequence, a range of solutions.  As per usual, a good history of the presenting complaint is crucial to finding an answer.  Let’s look at some of the most common causes.

1.  Atrophied fat pads.  As we age we tend to loose the quality and quantity of the fat pads under our feet.  This leaves the underlying bony architecture more prominent and prone to irritation.
   
   
2. Plantar flexed 1st metatarsal head.  In a small portion of the population, the base of the PMA 1 region is dropped with respect to the remainder of the forefoot.  As a consequence it will receives more pressure for longer.
   
   
3. Sesamoiditis/Sesamoid anomalies.  Under the base of the PMA 1 region there exists a pair of sesamoid bones designed to improve the function the of the big toe.  These are perfectly normal but on occasion can become painful due to trauma or degenerative change.
   
   
4. Cavoid foot type.  A high arched immobile foot type tends to increase plantar forefoot pressures.
   
   
5. Mobile foot type.  A flexible mobile foot type can load the base of the PMA 1 region under high load conditions.
   
   
6. Long first metatarsal.
   
   
7. Flexor Substitution.  In instances where there is weakness in the calf muscle group, triggering and clawing of the toes may occur as a compensation.  There are a range of muscle imbalances that can cause digital contraction and increase plantar pressures.  
   
   
8. Incorrect cleat position.
   
   
9. incorrect shoe size/type.

There are other less common reasons for PMA 1 pain including vascular occlusion, neurological impairments and callus formation amongst others.

Solutions

The most common method of reducing peak pressure under the PMA 1 region is with a cut out.  The risk with a simple cut out is you sometimes will create a space for tissue to extrude into and over time worsen the condition.  Usually, when we are providing simple deflection, we will do so with dual density material to minimise the potential for tissue herniation.

With mobile foot types, providing a cut out can exacerbate the condition as it will tend to roll the foot further over and destabilise the foot inside the shoe.  In these cases, you may end up moving the centre of pressure more medially (towards the PMA 1 region).   In cases where a mobile foot type is paired with high PMA 1 pressures, we may look at varus wedging on a Cobra9 Pro device to shift the centre of pressure laterally whilst providing some deflection under the PMA 1 region.

If the cleats are too far forward or skewed medially/laterally, high PMA 1 pressures may result.  Incorrect fitting shoes especially when too long, can worsen the condition as the natural shape of the carbon sole will taper too late and place increased pressure under the ball of the foot.

At Cobra9 we tailor orthotic solutions based upon the underlying case presentation.  Our SemiPro devices are designed to assist with this issue and a slew of other presentations with appropriate contour and dual density materials but on occasion, a more targeted approach with a Pro device may be the answer.