Bone Stress Injuries in Distance Runners: Overload, Underfuelling and Lacing Up
Bone stress injuries are far too common in the runner, but they can't be ignored, and must be treated with depth. Here's what you need to know, and how exercise physiology can support you with the ultimate goal: lacing back up!
Distance running is a unique sport with unique quirks, characters and training demands. All runners know somebody enduring a bone stress injury (BSI). That person will either be well educated about the causes of the injury (training error, low energy availability [LEA] or excessive mechanical loading) or will simply blame their shoes and the hard surfaces of the modern era (2, 3). Let’s dive into the well-documented research on BSIs and the influence of significant training overload and LEA.
The Training Error
A BSI can be defined as a load-related, non-traumatic structural injury to bone that results from mechanical fatigue (2, 3). Distance running applies repetitive, uniform loading, which offers diminishing returns for osteogenesis (new bone formation) because bone cells become desensitised to repeated identical loads (5). When load is excessive, microdamage accumulates faster than bone can repair it (2, 3). Strain magnitude appears to matter most: the greater the strain, the fewer loading cycles bone can tolerate before failing (3). Small increases are consequential, with a 10% rise in strain estimated to halve the number of tolerated cycles (5), although I strongly believe risk is influenced by many factors, including training history and subsequent recovery.
So, when you analyse your chronic training load with your coach, remember that weekly mileage is not the sole measure of the total load endured. In a large cohort of runners, week-to-week mileage changes were less informative than single-session spikes (4), and high running velocity has a disproportionately higher bone strain (5). The percentage of intensity within your mileage may be a better indicator of risk.
The Fuelling Error
The real question lies in the relationship between mechanical overload and energy availability. The IOC defines LEA as a mismatch between energy intake and the energy expended in exercise, leaving inadequate energy to support the body’s optimal function (1). LEA exists on a spectrum, and mild or transient LEA can be adaptable, while problematic LEA is the concern (1). When problematic LEA is sustained, it can lead to the syndrome of Relative Energy Deficiency in Sport (RED-S), which broadened the earlier Female Athlete Triad framework to include male athletes and wider effects (1).
RED-S weakens bones and raises susceptibility to stress fractures (1). Other health consequences include, but are not limited to, amenorrhoea (in women), reduced bone density, downregulated hormonal function, impaired growth and development in younger athletes, immunosuppression, psychological distress (anxiety, depression, disordered eating) and other metabolic disorders (1). Athletes may notice reduced performance before any of these health consequences, including injury, increased recovery needs, decreased muscular strength and power, increased irritability and impaired judgement (1).
The Return-To-Run
Once a BSI and/or RED-S has been assessed and diagnosed, it is important to consider what returning to training will look like (and yes, we count rehab as training!). Bone needs to be reloaded across different magnitudes, rates and planes to promote diverse adaptation (5, 6). Initially, we achieve this through targeted strength and plyometric training, specific to the site of injury. Where RED-S is part of the picture, we also bring in a broader team, including a sports dietitian and a sports/exercise physician. This team can also help with a BSI that isn’t related to RED-S.
The return to run depends on the site of injury and may be painstakingly slow, but it is well worth the commitment. Then we can get back to doing what we love most: lacing up!
Takeaway:
Avoid sudden load spikes (including % intensity!), assess energy availability (integrating a sports dietitian if needed), and rebuild bone with progressive, varied, heavy loading prior to returning-to-run/play.
If you are currently suffering from a BSI, or something more acute, surround yourself with a caring and committed team – that’s what we do at SOS Exercise Physiology! Book here for a free discovery call so we can chat about your running journey.
References
Mountjoy M et al. Br J Sports Med. 2023;57(17):1073–1097. doi:10.1136/bjsports-2023-106994 (IOC consensus)
Hoenig T et al. Br J Sports Med. 2025;59(2):78–90. doi:10.1136/bjsports-2024-108616 (Delphi consensus)
Warden SJ, Edwards WB, Willy RW. Curr Osteoporos Rep. 2021;19(3):298–307. doi:10.1007/s11914-021-00666-y (review)
Frandsen JSB et al. Br J Sports Med. 2025;59(17):1203–1210. doi:10.1136/bjsports-2024-109380 (cohort)
Jeanguyot E. Aspetar Sports Med J. 2026;15 (narrative review)
Warden SJ, Edwards WB, Willy RW. J Orthop Sports Phys Ther. 2021;51(7):322–330. doi:10.2519/jospt.2021.9982 (review)
Hoenig T et al. Br J Sports Med. 2023;57(7):427–432. doi:10.1136/bjsports-2022-106328 (meta-analysis)
