As I discussed in Part 1 of this series, heel striking during gait is “unnatural” and prevents the body from using its natural shock absorbing mechanisms. Each jarring step can put you one step closer to shin splints. Have you ever had shin splints? If you are or ever were a runner, then you know the pain I am talking about. A sharp pain on the inside and back part of the shin bone that is worse after each high impact step you take. I spent a fair amount of time in college icing my shins as a result of shin splints. I had the opportunity to get to know the pain all too well. There is currently not a whole lot known about the cause of shin splints, but one cause can be inflammation of the tough membrane with some elastic properties called the “interosseous membrane” that lies between the two bones of the leg. The interosseous membrane helps to transfer some of the impact from walking from the main weight-bearing bone, the tibia, to the other bone of the lower leg, the fibula.
Just like you, I always thought this pain was limited mainly to runners or other high impact sports. My experience evaluating people on a daily basis suggests that nearly everyone has a “silent” version of shin splints. If you do not believe me, try pressing along the backside of the shin bone along the inside of your leg. Chances are that you are a lot more tender and sensitive here than you may have realized. Luckily unless someone puts pressure there, most people are not even aware of the tenderness and tension they carry in that area. I find that this tension plays a role in knee pain, back pain, and more as it chronically gets worse.
So how does the interosseous membrane become inflamed? During a proper landing on the fore foot during gait, the heel comes down while your calf muscles contract and your achilles tendon becomes taut. It smoothly spreads out the impact like a system of pulleys. During a heel strike, a high pressure jolt drives the heel straight up into the tibia causing a quick jarring of the interosseous membrane. The transfer of pressure is not smooth and makes the membrane more prone to tears at its attachment site.
Another piece that I believe contributes to shin splints is contracted and tight muscles that curl the toes. These muscles are the flexor digitorum longus and flexor hallucis longs. These muscles, along with tibialis posterior, attach directly on the inner-backside of the shin bone right where people usually complain of shin splints. The reason I believe this to be the case is because the more deformed toes become as a result of chronic shoe wear, the more tender to touch this area becomes. Various features in shoe design including a pointed tip compressing the toes together and an upward curvature at the end of the toe box contribute to most toe deformities we see. The structural changes at the toes cause the muscles attached to them to contract as a result of joint protective mechanisms.
Knowing this information, you have two choices. You can continue doing nothing, hurting yourself with each step you take, hoping that you do not end up with aches and pains in the future. The other is that you can take action now to ensure that you have done the best you can to prevent problems. If you would like your life to be pain free where you’re not having to deal with shin splints and foot deformities, then you must make changes. First, you must learn to use proper form that does not include heel striking. Second, you must find shoes that do not deform your feet. Third, you must restore flexibility to your feet again either by yourself or through a hands-on therapist.