Shin Splints: Fracture or Function
As the weather slowly starts to warm, we all start spending more time outside. In an effort to kick the winter doldrums, many of us start to dust off the running shoes and start to pound the pavement. With this rapid increase in activity, old and new injuries often pop up. We wanted to take this month to address some common running associated injuries and talk through how they occur and how to train to avoid them.
First up is the ever dreaded shin splints, or medial tibial stress syndrome (MTSS) as it is appropriately called. Shin splints get their name from the idea that we are splintering the shin bone. However, usually that is not the case. Yes, occasionally someone can develop fractures of the tibia (shin) but typically that does not happen. MTSS comes from a compilation of muscles of the shin pulling on their insertions on the tibia, poor hip and knee control, too much mileage, too fast, for too long, poor technique, and a cross over gait. The basis for MTSS boils down to too much damage without enough time to recover that overloads structures and causes injury.
So, what is the practical application of all this? First, is to avoid the too’s, that is too much mileage, too fast and too long. Look at your current base of milage (your weekly average) and then don’t increase more than 10% of that per week. This will keep you from quickly overloading the system and causing an injury.
The next easy metric to look at is the strength of your leg. Injury rates in general have been found to be lower in individuals that hit certain strength benchmarks. Our hip abductors (lifting the leg out to the side) need to be greater than or equal to 35% of your body weight, meaning if you weigh 200lbs, you need to be able to generate 70lbs of force out to the side. Strength of the hip abductors is especially important because they prevent excessive inward rotation at the knee. When we have excessive inward rotation of the knee, more load gets passed onto the passive (not muscle) structures in the leg. These structures then get overloaded and injuries start to occur.
Then we want to look at the flexibility of our tissues. When we run, our joints need to be able to go through specific ranges of motion. If we have limitations, we start compromising other places. This can lead to injuries like MTSS. So, the prescription for limited ranges of motion is stretching followed by a control exercise. This pairing helps open up new ranges of motion while teaching the brain how to control those new motions. This combination of exercises leads to bigger and more permanent improvements in range of motion. To get a meaningful improvement in flexibility of a tissue, we need 5 minutes of stretching in a week for that muscle group with a stretching session being at least 30 seconds. You then want to take the muscles you stretched through their full range of motion slowly with a maximum contraction. This is the motor learning piece that teaches the brain to control and keep the work you just did.
While it is very difficult to prevent all injuries, but by increasing tissue flexibility, hip strength and paying attention to your training load, you can prevent a whole host of injuries including MTSS.
Khayambashi K, Ghoddosi N, Straub R, et al. Hip Muscle Strength Predicts Noncontact Anterior Cruciate Ligament Injury in Male and Female Athletes: A Prospective Study. Am J Sports Med. 2015;(44):355-361.
William D Bandy, Jean M Irion, Michelle Briggler, The Effect of Time and Frequency of Static Stretching on Flexibility of the Hamstring Muscles, Physical Therapy, Volume 77, Issue 10, 1 October 1997, Pages 1090–1096,
Thomas, Ewan, et al. “The Relation between Stretching Typology and Stretching Duration: The Effects on Range of Motion.” International Journal of Sports Medicine, vol. 39, no. 04, 2018, pp. 243–254., https://doi.org/10.1055/s-0044-101146.
Wyon, Matthew; Felton, Lee; Galloway, Shaun. A Comparison of Two Stretching Modalities on Lower-Limb Range of Motion Measurements in Recreational Dancers. Journal of Strength and Conditioning Research 23(7):p 2144-2148, October 2009
