First and foremost this article is going to be jargon heavy. This will be hard to read especially by those who have had no formal introduction to human anatomy. However, worry not! I will simplify this article in the future. This article is a brain dump essentially.
With that out of the way let's get to it.
Shin pain - what it is, and who is affected by it the most?
Shin pain is an overuse injury which is most common in people who run, or jump quite a lot. Even a overweight person who starts walking and scales distances quickly can accumulate enough stress on the shin to cause shin pain.
Shin pain in its most benign form is not a problem most of us go through it, and it resolves by some RICE(rest, ice, compression, and elevation), followed by certain stretching and strengthening exercise. If no steps are taken to mitigate this low grade pain it can become ginormous and cause significant disruption to life and training. The worst of shin pain is a stress fracture that will take you off your activity for weeks and will be followed by physiotherapy and strengthening.
However, the worst thing about shin pain is not even the pain, but the fact that we can do all the strengthening and stretching in the world, it recurs quite frequently. This shows that most approaches that aims to alleviate the risk of future injury are faulty and here's how you can correct it.
The traditional approach to managing shin pain involves lot of stretching of the hamstring, calves, tibialis anterior muscles, and the toes. As good as these exercises are, this approach solves the symptom not the cause.
To understand the players of the game. Let us understand the anatomy of the leg once again. There are so many muscles in the leg that they have been divided in 3 compartments. Anterior, posterior, and lateral compartment.
Muscles of the anterior compartment -
Tibialis anterior, Extesor digitorum longus (EDL), externsor hallucius longus (EHL), and fibularis tertius.
Muscles of the posterior compartment -
Muscles of the Superficial posterior compartment -
Gastrocnemius, soleus, plantaris (absent in 10% of the population)
Muscles of the deep posterior compartment -
Flexor digitorum longus, flexor hallucius longus, tibialis posterior, popliteus.
Muscles of the lateral compartment
fibularis longus, and fibulars brevis.
There are four motions available at the ankle joint as a result of these muscles
Motion | Primary Muscles | Secondary muscles |
Dorsiflexion | Tibialis anterior | EDL, EHL, Fibularis tertius |
Platarflexion | Gastrocnemius, soleus | FDL, FHL, Tibialis posterior, Fibularis longus, and Fibularis brevis |
Eversion | Fibularis longus, Fibularis brevis | EDL, EHL, Fibularis tertius |
Inversion | Tibialis anterior, Tibialis posterior | FHL, FDL, Gastrocnemius, and Soleus |
Now, try visualizing two forces one laterally along the leg (everting force) and other medially along the leg (inverting force). These two force are a force couple. When they are balanced, the ankle as its bearing more and more weight as we move from the heel strike to the stance, allow the foot to evert at the ankle lightly and then return the ankle to it's neutral position therefore returning the inverted and arched position of the foot from where the big plantarflexors launch the body again.
What happens when we disturb this force couple, making the lateral force more dominant? The lateral force vector everts the foot, therefore as we transition from heel strike to stance the foot continues to evert at the ankle joint. This causes the tibialis anterior and other inverters of the foot to contract eccentrically very powerfully to protect the ankle from injury causing these muscles to become overworked that will eventually lead to shin pain.
The primary everters, the fibularis longus and brevis then continue to contract thus plantarflexing the foot and propelling the body forward. The fibularis muscles are not big enough to do this without causing some some painful adaption to it's structure.
The rapidly everting foot also causes the tibia and consequently the femur to internally rotate. It leads to a tight glute medius that can alter the gait thereby reinforcing a faulty muscle recruitment pattern.
Now, the million dollar question is what causes this muscle force couple to alter? There could be many answers but the two most common answers are -
Weak arch in the feet
Preferring one leg over another as the stance leg.
1). Weak arches cause the cycle described above that leads to shin pain.
2). Preferring one leg over another as the stance leg, the mechanisms are different for different people. However, two most common mechanism are -
When your hip internally rotates on your stance leg
When your hip externally rotates on your stance leg
These factors in addition to other bodily asymmetries must be properly assessed to device a plan that helps you plan the best individualized plan for managing shin pain.
Thus, i conclude this article, after having shown that treating pain just around the shin is not enough. We need to take into account the entire hip and leg in order to prescribe a proper protocol that will help the client get better and continue to train without pain.
In the next article I will discuss a couple of protocols to manage shin pain. Thanks for reading.