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What is a stress reaction, and how can you prevent one?

Molly Seidel missed world championships because of a stress reaction; how can the rest of us stay injury-free?

Molly Seidel 2022 from Instagram

Avoiding injury is the goal of every runner, and that includes preventing a season-ending (and painful) stress reaction. Olympians Molly Seidel and Gabriela DeBues-Stafford have both been sidelined this year with stress reactions; ultrarunner Gary Robbins had to pull out of his 2019 Barkley attempt due to one. So what is a stress reaction, and how can a regular runner prevent it?

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A post shared by Gabriela DeBues-Stafford (@gabrielastafford)

Stress injuries: the basics

Readers may be more familiar with the term “stress fracture,” which is further along the stress injury spectrum. (In other words, a stress reaction may lead to a stress fracture if left untreated.) The cause of the initial reaction (and subsequent possible fracture) is usually overuse, as opposed to more serious traumatic types and of fractures from falls or other accidents.

Stress injuries are classified upon diagnosis: early (stress reaction) or late (stress fracture). A stress reaction can be considered similar to a deep bone bruise. A stress fracture is a small hairline crack in the bone.

Stress reactions are usually diagnosed through an MRI, and we see pro athletes catch their injury at this early stage because they’re more likely to have quick access to medical technology. Regular runners often don’t realize they have a serious injury until an X-ray shows a stress fracture.

Why are runners vulnerable?

Runners tend to get stress injuries in their leg bones, feet and hips due to the repetitive nature of our sport. DeBues-Stafford’s and Seidel’s stress reactions were in their sacrums (the triangular bone at the base of the spine, just above the tailbone); Robbins‘ was located at the head of his femur (thigh bone), close to the sacrum.

The pain from this injury is often barely noticeable at first, but progresses over time until you can even feel it at rest. Runners may be used to running through niggling pain and soreness and will ignore the symptoms of a stress injury until it’s past the reaction stage.

Proactive steps 

Overtraining and underfuelling are major contributing factors to stress injuries.

A paper in the Journal of Orthopaedic and Sports Physical Therapy reported that while micro-damage to tissues and bones is essential to athletic improvement, stress reactions occur when the strain caused during accumulated activities is disproportionate to the body’s ability to recover.

What does that mean for the regular runner? Be mindful of nutrition, recovery and training load. Running a big marathon build, but not fuelling appropriately for your body to actually repair the incremental damage done by that build, is a recipe for disaster.

Allowing appropriate recovery time (including sleeping 8-9 hours per night) after hard sessions or training blocks and eating enough nutritious food to fuel that recovery are essential to avoiding stress injuries. (They’re also key to becoming a faster, stronger runner.)