Shin pain can be a frustrating, viscous cycle. Shin pain is not a diagnosis, but rather a vague term for where you hurt. The injury itself can be somewhat minor (shin splint) or rather major (stress fracture). Generally, the development of shin pain can be abrupt, but usually the runner is at fault. A minor shin splint improves as you run (“warms up”), but the absence of symptoms doesn’t translate to absence of damage. As you run the injury slowly worsens and eventually the tide turns. That measly “I can run through it” shin pain develops into distinguishable, distinct, dig with your fingertips type pain.

At first glance you may think that a shin injury is an impact injury. Well, yes and no. Inner shin issues (shin splints, stress reactions, and stress fractures) arise from tensile forces to the bone-not compressive. Our skeletal system craves compressive forces–the bone responds to compressive forces by building more bone, thus making it strong. On the other hand, tensile (pulling) forces are bone kryptonite. The easiest analogy is to think of bending a tree branch. As the branch bends, it’s not the compression side that breaks, but the tensile side. As our foot strikes, the ground reaction force transmits through the foot and up the chain into the spine. The ground reaction force attempts to bend bones at a repetitiously at a high velocity.

These tensile epicenters, the lower inner shin being one localized area, are structurally supported by our muscles. The muscles pull up and prevent the analogous tree branch from bending. Lower shin injuries are not a product of a single foot strike, rather a repetitive, rapid tensile load that occurs during every foot strike. If you’re muscles are simply unable to stop the tree branch (bone) from bending, the result is irritation (shin splint), to bone inflammation (stress reaction), and eventually breaking (stress fracture).

A retrospective study found that 50% of stress fractures are found in the bottom third of the tibia.¹ Causation is multifactorial. For example, in this article I discuss the link between muscle fatigue and the rate of acceleration and loading while running. In short, increasing fatigue causing quicker loading rates between body and the ground, while the acceleration of the tibia (shin) progressing forward increases. The studies outlined in the previous article are relevant when we link them to other research studies. Milner et al. found that the occurrence of stress fractures in female runners was related to greater initial loading of the lower extremity.²

It all sounds like an impact issue, right? Don’t be fooled. It’s not the landing that’s causing these injuries, but the poor control of landing. Your body weight doesn’t fluctuate when you run (outside of sweating). Body weight is constant, but loading rates can change drastically. Without strength at key areas the loading rates between your body and ground maximize. Another research study focused on female runners showed that, when compared to controls, the stress fracture group demonstrated increased hip (peak hip adduction) and knee motion (internal rotation).³

Ultimately, an unattended shin splint will progress. A slight “ache” transforms into pain that limits you from running (stress reaction) and ends with pain that is present with walking and standing (stress fracture). You’ll want to focus on strengthening key areas with runner-specific exercises. Targeting your hips, knee, and lower leg can help prolong fatigue and devastating tensile forces.

Wondering where to start with your hip strength? Start with our BaseSix Bootcamp.

References

1. Monteleone, G. P., 1995. Stress fractures in the athlete.Sports Med. 26, 423–432.
2. Milner, C.E., Ferber, R., Pollard, C.D., Hamill, J., Davis, I.S., 2006b. Biomechanical factors associated with tibial stress fracture in female runners. Medicine and Science in Sports and Exercise 38, 323–328.
3. Milner, C.E., Davis, I.S., Hamill, J., 2005. Is dynamic hip and knee alignment associated with tibial stress fracture in female distance runners? Medicine and Science in Sports and Exercise 37, S346.