Big toe?! Yes the big toe and the joint, the 1st metatarsal, plays a huge part in foot function and our likelihood for running injuries. Many common injuries such as generic shin pain and painful arches (plantar fasciitis) can all be due to 1st metatarsal and big toe function.
Firstly, and simple put you have 5 metatarsals in each foot. The Great Toe is has functions in the propulsive phase of the foot and well as foot stabilisation. Underneath the 1st metatarsal you have attachment point of your flexor hallucus longus (FHL). This tendon runs underneath the arch of the foot and aids flexion and extension on the Great Toe. A key muscle which originates on the 1st metatarsal is the posterior tibilalis. This muscle runs under the arch of the foot and inserts medically to the calf (on the inside). These two will be important later.
Now, anatomically the great toe can sit in different positions to the ground when the toe is flexed (see picture below). Now if it lies closer to the ground we call it plantar flexed. It is therefore the key stabiliser of the foot as it is the initial point of contact with the floor. This causes high pressure loading on the joint. The other position is obviously when the other four metatarsals sit lower. This means when the foot strikes the floor the 1st met has a long way to travel and then has to work extra hard to control the foot. The function of the Great Toe can really impact the whole foots function.
How does this link with injury? Well when the big toe takes greater load than the rest of the foot the muscles under it have to fire a lot quicker and stronger to stabilise the foot. Therefore, it is very common that plantar fasciitis can come from a stiff big toe joint not functioning correctly! In regards to shin pain (medial specifically) they can occur purely due to the big toe overworking again, to stabilise the foot. The posterior tibilalis has to pull and work harder which can offset the calves to fire more, cause them to tighten and thus the dreaded shin pain!
Now it’s in these situations that shin pain or sore arches can be reoccurring. A simple solution such as constantly rolling the foot under a golf ball to help loosen the muscles can help. But in these cases a long term solution would be some sort of insole to help with pressure distribution as well as help level off the foot.
I hope this all makes sense any questions drop it in the comments below 🙂