A bone stress injury sits on a spectrum. At the mild end, repetitive load outpaces the bone’s ability to remodel, causing a “stress reaction” — inflammation and early weakening without a visible crack. Left unaddressed, that can progress to an actual stress fracture, a hairline crack in the bone. Both come from the same mechanism: too much load, too little recovery, for too long.
Where they happen
Runners and jumping-sport athletes are most affected, most commonly in the tibia (shin) and metatarsals (foot). Some locations carry extra caution because they heal poorly or risk a complete fracture: the femoral neck, the anterior (front) surface of the tibia, and the navicular bone in the foot are considered “high-risk” sites that need more careful management than a typical low-risk stress injury.
Recognizing it
Pain that builds gradually with activity and eases with rest, localized to one spot on the bone, and tender to direct pressure there. A hallmark clue is pain that starts later and later into a run or session as the injury progresses, eventually showing up at rest too. See our X-ray guide for why plain X-rays often look normal in the first 2–3 weeks — MRI or a bone scan is more sensitive early on and is often used when a stress injury is suspected but not yet visible on X-ray.
Treatment
Unlike most injuries on this site, the core treatment is offloading, not exercise — continuing to load a stress injury is exactly what causes it to progress toward a full fracture. Depending on the site and severity, this ranges from simply modifying activity and cross-training (cycling, swimming) to a period of protected weight-bearing in a boot, and occasionally surgery for high-risk sites that heal poorly on their own (like the femoral neck or navicular). A gradual, structured return to running — not a fixed calendar date — follows once you’re pain-free with daily activity.
Why it keeps coming back for some athletes
A single stress injury from a sudden training spike is common and usually straightforward. Recurrent stress injuries, or one with surprisingly little training behind it, are a different story — they’re one of the clearest warning signs of RED-S (low energy availability), and warrant a broader look at training load, nutrition, and hormonal health rather than treating each fracture as an isolated bad break. Adequate calcium and vitamin D intake support bone health throughout recovery and prevention.
This page is educational and general in nature and does not replace an individualized evaluation — see our medical disclaimer.