The 6 Most Common Risk Factors for Stress Fractures in Running

Unidentified shin pain is an incredibly common gripe for runners, and determining what exactly that pain is can be a frustrating, ambiguous process.

After all, most resources tend to assign any old shin pain as shin splints — which isn’t inherently wrong, but there’s more to the symptoms than a vague umbrella term.

With shin splints, you’re dealing with localized pain in the front of your lower leg bone. One of the telltale signs is that the pain usually worsens during activity and alleviates with rest. Most often, shin splints occur due to overuse, which leads to muscle tightness and changes in the tendon. These gradual but repetitive issues result in extra stress placed directly on the bone itself.

And that stress is a key consideration. While many instances of recurring shin pain can be classified as shin splints, your symptoms can be the warning sign of a larger potential injury: a stress fracture.

So, let’s delve into how this injury comes to be (and how to catch it well before it becomes a problem for you).

What is a Stress Fracture?

You may be able to infer what this injury is based on the name alone: it’s a small fracture of the bone brought on by excessive stress and repetitive forces. (Hence, why it’s a relatively common injury for runners.)

If runners lack sufficient shock absorption, their bodies are subjected to repetitive impacts with every step they take. This is why they often sustain stress fractures in areas within the lower extremity, some of the most common sites being the pelvis, femur (thigh bone), shin, and 5th metatarsal (the outermost long bone of your foot — the one that connects to your pinky toe).

As mentioned earlier, stress fractures are bone injuries that occur as a result of untreated issues within their corresponding muscles. If one of your muscles gets strained, the overuse can render the muscle ineffective at properly absorbing shock upon impact. This consequently transfers the impact forces onto passive, inflexible structures like your bones — and that impact is where the problems grow more severe.

The impacts of running occur so frequently and at such a rapid rate that your bones don’t have enough time to rebuild themselves before your next run (this is known as a “stress reaction”). If you continue to run as usual without ample rest for your body, this repetitive stress will eventually lead to tiny breaks in the bone that constitute a stress fracture.

Sustaining an actual stress fracture is a difficult injury to cope with. Properly recovering from the fracture means no running for at least 4-6 weeks (sometimes more, depending on the severity) while using a walking boot or cast to help support the bone’s healing.

So, while it’s important to understand how a stress fracture comes to be, it’s doubly as important to recognize the risk factors in an attempt to prevent or worsen injury.

Common Causes of Stress Fractures

Running injury prevention is rooted in one primary training aspect: mastering proper running biomechanics and technique.

But of course, that’s much easier said than done. Most runners don’t know the nitty gritty details behind ideal running form, let alone how to achieve it. So, let’s take some time to break down a handful of common risk factors associated with the stress reactions that can lead to stress fracture so you know how to tailor your training for more targeted injury prevention.

#1. Taking on Too Much, Too Soon

A sudden increase in running volume, duration, or intensity is frequently linked to a high risk of developing a stress fracture.

Many runners experience this pitfall, as it’s easy to push yourself harder and faster when your workout feels like a breeze. Plus, when you’ve hit your stride and start feeling good, you’re naturally going to want to challenge yourself with a tougher run.

This can be especially true for younger athletes, like 12-14 year olds participating in cross country or track and field. Youth athletes often dive headfirst into their training at the start of a season, neglecting a proper running progression or any off-season training.

Though it’s tempting to go all in with your running, gradual training is essential! Running places incredibly high loads on the body, so it’s key to ease into your mileage and supplemental training to ensure you build up sufficient strength, muscle activation, and technique to tolerate the demands of increased running.

#2. Vertical Posture while Running

Runners are often advised to “run tall,” but this often leads people to believe that they need to keep their back upright and perpendicular to the ground.

This is another common form error we see all the time — runners often present insufficient trunk lean, which ultimately increases the impact loads. When you land with an upright spine, you’re limiting the amount of joint flexion at your hip joint, consequently affecting your muscle contraction through your entire kinetic chain.

And insufficient muscle contraction has a direct impact on your shock absorption: the primary culprit for sustaining stress fractures over time. Your posture may seem less important than other facets of your running form, but that just goes to show how nuanced your biomechanics can really be!

So, instead of running “tall” and ending up straight up and down, lean forward just slightly from the waist (as if you were running into a stiff wind). This will put just enough bend into your hip to allow for better shock absorption. 

#3. Increased Ankle Flexion

Many runners don’t actively think about the angle of their ankle while running, thus making it a common problem area that can contribute to stress fractures.

In particular, the issue occurs with increased ankle dorsiflexion (or, when your toes move towards your shin). When your ankles present an excessive degree of flexion, it’s indicative of insufficient muscular activation and contraction through the lower extremity, like weakened calf muscles. This consequently limits the amount of active shock absorption available in your legs, thus increasing the overall impact forces of your running.

Excessive ankle dorsiflexion is most commonly associated with stress fractures in the calcaneus (the main heel bone) and the tibia (the larger shin bone).

#4. Vertical Oscillation

If you’ve never heard of this term before, it sounds more complex than its technical definition: excessive vertical motion while you run. (Also sometimes referred to as “bouncy” running.)

Additional up and down movement — even if it seems minimal to the naked eye — can have a large effect on your landing impacts. The more your body moves up during the “float” phase of your running (i.e., when neither of your feet are touching the ground), the greater the forces your body has to sustain upon landing each step.

Plus, when so much of your gait cycle is taken up by vertical motion, you aren’t able to focus all of your energy and biomechanics into forward propulsion. Not only are you subjecting your body to higher rates of passive shock absorption, but you’re also directly limiting your bodily efficiency to run faster and longer.

#5. Low Cadence

If you’ve ever looked up how to run faster or better, this one probably sounds familiar.

The running community has well-established the importance of running cadence: that is, how many steps you take per 1 minute of running (also referred to as steps per minute or SPM). On average, the ideal running cadence lands between 170-180 SPM.

While this range may not be the ideal cadence for every runner, it’s a solid range to strive for. Most runners who have a cadence below 170 SPM experience higher rates of impact forces, thus having a higher likelihood for sustaining stress fracture injuries.

Perhaps it seems counterintuitive — how does taking fewer steps increase your impact forces?

There’s actually a lot of reasoning as to why a higher cadence is better for your running. One of the biggest benefits is that it generates a higher step turnover rate, which ultimately promotes better running form (e.g., by decreasing your chances of over-stride, eliminating vertical oscillation, or encouraging ideal joint angles and muscle contraction, to name a few).

#6. The Female Athlete Triad

An unfortunate (but important) consideration also comes down to your biological sex. Research has shown that females are more likely to sustain stress fractures compared to males.

This has been correlated with the “female athlete triad,” which refers to a set of 3 common wellness concerns for young, female athletes:

Each of these potential concerns present issues that go beyond injury prevention in running, so if you begin to present any symptoms, it’s best to seek additional support from the appropriate medical professional.

While experiencing any of these conditions doesn’t necessarily restrict you from successful running, it does make it more difficult to safely sustain the demands of your training. So, addressing any of these potential concerns comes first and foremost — your well-being shouldn’t come at the expense of consistent training.

How to Prevent Stress Fractures

Most treatment plans will adhere to a gradual, walk-to-run progression, later followed by some strength training and stretching regimens. This is the standard protocol for trying to heal the fracture and easing you back into running, but it rarely addresses the reason you sustained the injury in the first place.

And that’s the real key for prevention: understanding the root cause, and how to fix it.

While you can likely infer that your stress fracture is brought on by some degree of improper shock absorption, being able to truly address the issue requires more specific data.

The best solution is to experience a thorough running gait analysis, where highly advanced technology can record data specific to your unique running form. In our particular clinic, we utilize a wide range of equipment, including IMU sensors to measure your joint angles, high speed cameras to capture every frame of your gait cycle, and a highly pressurized treadmill to measure the pressure of your footfalls — all in real-time.

With the right biofeedback (and the proper expertise to dissect it), you’ll have an in-depth understanding of what particular biomechanics are preventing your ideal running form and increasing risk of injury instead.

So, what are you waiting for? Don’t let the risk factors alone stress you out: book a gait analysis to learn what nuances may be affecting your form and how you can go about correcting them for faster, better running.

By Dr. Kevin Vandi DPT OCS CSCS

Dr. Vandi is the founder of Competitive EDGE Physical Therapy — with his background in physical therapy, orthopedics, and biomechanics, he is a highly educated, compassionate specialist. Using state-of-the-art motion analysis technology and data-driven methodologies, Kevin has assisted a wide range of clients, from post-surgery patients to youth and professional athletes. When he isn’t busy working or reading research, he spends his time with his wife Chrissy and their five wonderful children, often enjoying the outdoors and staying committed to an active lifestyle.

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