Factors that contribute to shin splints in runners

The term shin splints is used to describe pain in the medial tibia, also known as your shin bone, making it a very broad term. Shin pain could be caused by anything from mild chronic training stress, to more severe issues like muscular tears or stress fractures.

Another contributor could be a condition known as exertional compartment syndrome, which causes pain, swelling, and disability due to excessive pressure within the muscle compartments of the lower leg. Though the exact mechanism is not yet fully elucidated, the basic mechanism seems to be that muscles in the lower leg swell and expand in response to chronic exercise, while the fascia that encases those muscles remains unchanged and does not provide space for expanding muscle. The resulting increase in pressure can be quite painful.

Why early detection is important

10-20% of all running injuries involve shin splints. Shin pain also accounts for 60% of all lower-body overuse injuries. Severe shin splints can be very painful and derail an athletes training. An athlete with shin splints may be forced to miss training, or even skip entire seasons in order to recover.

This makes the early detection and prevention of shin splints and important consideration for any runner.

Risk factors

There are many subtle factors within a runner’s gait pattern that affect the repetitive stress that they place over their shins, and thus their risk for shin splints.

Tibial acceleration strongly correlates with risk of shin splints and can be thought of as a proxy for the amount of shock absorbed by the shin bone during each stride. It’s reflective of the rate at which the shin decelerates to absorb shock and then re-accelerates to forcefully propel the runner forward. Higher rates of tibial acceleration increase the risk of shin splints.

Vertical loading rate is the measure of how much force is being transferred vertically into the ground through the foot and lower leg of a runner. More efficient runners have decreased vertical loading rates because more of their energy is used for forward, horizontal propulsion rather than being wasted with vertical motion that doesn’t increase running speed.

Factors such as running cadence and vertical oscillation, which we’ve covered in depth in previous articles, strongly affect vertical loading rate and shin splint risk.  

Knee flexion excursion is the measure of how much motion the knee joints have while absorbing and generating force. For example, if someone is recovering from an ACL surgery, their recovery progress can be assessed by how much their knees move when they hop up and down. Greater knee movement while hopping means better knee function, and better progress in recovery.

The same idea applies in running, and “stiffer” runners have less knee flexion excursion with each stride and are less able to attenuate shock. When the knees mitigate less shock, that increased impact force is then transferred through the shins with each stride.

Tibial angle is another potential risk factor for shin splints. This is the angle of the tibia toward the midline of the body. Ideally, there is a nearly vertical line running from the femur, across the knee and through the tibia to the ground. If the knee buckles inward or bows outward and changes the angle of the tibia relative to the ground, it can increase stress across the shin and knee joint.

During running, the body experiences vertical forces equal to 2.5 - 2.8 times the runner’s bodyweight. If the tibial is angled inward or outward rather than positioned vertically and in-line with this force vector, it can increase bending forces on the tibia with each step, which elevates the risk for stress fractures or shin splints.

Every one of these factors can be changed and improved with training. The problem is that in order to assess these factors, you need a lot of technology that mostly exists in labs: things like motion capture video technology, pressure-sensitive treadmills, and multiple accelerometers taped to your shins. Smart watches can kinda-sorta estimate a few of these measures, like cadence and vertical oscillation, but they’re only a rough guess at best; trying to extrapolate what your lower body is doing based on the movement of your wrist.

The solution

The Cipher Skin knee BioSleeve is a form-fitting compression sleeve worn on the knee. It fits like a pair of compression leggings or yoga pants. It is comfortable, washable, and wireless.

The knee BioSleeve directly measures everything happening above and below your knee joint using complex, patented sensor technology. It can directly measure all of these critical aspects of running gait and provide real-time feedback on your performance and injury risk.

With this technology, you can objectively measure the many mechanical factors that affect the risk of shin splints or other lower body injuries. During training, you can immediately see if the changes you make to improve your running form are having their desired effect. You can also view daily changes in your form as well as receive real-time warnings mid-workout if you start to break down under fatigue and move in a way that increases your risk of injury.

This next-level technology means safer running, faster results from training, and better performance.


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