The symptom of shin splints is pain with every step, which becomes worse when walking quickly or running.
Anterior shin splints occur when the pain is located along the upper front part of the shin.
Posterior shin splints occur when the pain is located on the lower inside edge of the shin.
The tibialis anterior is the main muscle that bends upward, or dorsiflexes, the foot. It connects to the front of the tibia or shin bone.
The posterior tibialis is the muscle that pulls the foot down and in. It connects along the back and inside edge of the tibia.
Both muscles attach to the inside of the bones that form the foot’s medial arch and are involved in stabilizing the foot’s arch system.
What causes shin splints?
Optimally, the muscles that stabilize the foot’s arch system should fire prior to that foot’s ground contact, in anticipation of the expected ground contact weight-bearing and propulsion related forces. This muscle firing optimizes the efficiency of the arch system with the least degree of damaging stress.
Shin splints are usually caused by overuse, because:
- the tibialis muscles are doing too much too quickly
- the tibialis muscles are firing insufficiently or too late or
- because of maladapted neuromuscular function.
All of these result in an unstable arch system that easily collapses during weight bearing. As the arches collapse, there is a corresponding sudden increase in tension on the tibialis muscles. This sudden increased tension results in the excessive stresses on the tibialis muscles that lead to damage where the muscles attach to the tibia.
Over time, the edges of the muscles begin to microtear and pull away from the bone. The injured muscle and bone become inflamed and painful.