What Really Causes Running Injuries?
Exploring the interplay between tissue load, single-session spikes, and energy availability.
Whenever a niggle pops up, runners naturally look for a single culprit: Is it my shoes? My foot strike? The warm-up I skipped last week?
But injury risk isn't static, and looking for one isolated cause usually leaves you frustrated. On any given day, your risk depends on how well your body tolerates load, and that capacity fluctuates regularly. For example, a single night of poor sleep can change your risk profile, no matter how perfect your training plan looks on paper.
Ultimately, running injuries happen when training load, recovery capacity, and musculoskeletal tolerance fall out of alignment. How do you make sense of that for your own training?
We’re highlighting some key findings from current research to better arm you with the tools you need to stay injury-free on the run.
1. Previous Injury (The Strongest Predictor of Future Injury)
If you have experienced a running-related injury (RRI) in the past, your risk of sustaining another one increases substantially. A comprehensive systematic review identified a history of prior injury as the single strongest risk factor for long-distance runners.
Why It Happens
An injury leaves behind subtle changes even after you’re happily back to chasing running goals pain-free. Changes in tissue composition, tolerance to load and movement strategies mean that:
Tendons, muscles and bone may be more vulnerable to injury if they haven’t fully regained capacity to tolerate the load you’re asking of them.
Subtle changes in your movement patterns may shift loads to other tissues, creating an environment where they are being asked to work harder than they have capacity for.
Changes in your motor control and neuromuscular endurance can make you vulnerable to running through fatigue earlier than anticipated or asking too much of a given tissue.
Clinical Takeaway
Pain-free running is not the same as full recovery. Instead of stopping rehab the moment pain fades, complete a structured return-to-run program to restore peak tissue capacity and movement strategies that keep you healthy.
2. Single-Session Distance Spikes (Not Just Weekly Mileage)
A study published in the British Journal of Sports Medicine in 2025 followed over 5,200 runners across almost 600,000 runs. The results challenged the traditional belief that week-to-week changes in total weekly mileage could predict injury risk. A much stronger predictor of injury was how much distance you squeezed into a single run.
What the Data Showed
Running a single session that exceeded 110% of your longest run in the previous 30 days significantly increased overuse injury risk.
Doubling your recent longest run in a single session increased injury risk by over 128%.
Clinical Takeaway
Instead of obsessing over total weekly mileage, focus more on how you distribute volume across your week. If you want to increase mileage, add an extra short, easy run to your week or spread small additions across multiple sessions rather than pushing your weekly long run past what your tissues have adapted to over the previous month.
3. Underfueling & Relative Energy Deficiency in Sport (REDs)
According to the 2023 International Olympic Committee (IOC) consensus statement on REDs, running on an energy deficit triggers systemic physiological consequences that directly elevate injury risk.
In other words, if you underfuel, you’re much more likely to be injured.
Why It Matters
When you don’t consume enough calories to cover the energy requirements of both daily living and running, energy availability drops. This deficit impacts musculoskeletal health by:
Impairing bone turnover, increasing susceptibility to bone stress injuries (BSIs).
Reducing muscle protein synthesis, slowing soft-tissue repair and recovery.
Accelerating neuromuscular fatigue, which leads to poorer running mechanics later in a run.
Clinical Takeaway
Fueling is non-negotiable for runners! When you run, you create an environment where your body needs to adapt, or get stronger. But if you don't fuel properly, you can’t take advantage of that opportunity. Instead of building capacity, you risk lowering load tolerance across many tissues, and injury risk soars.
Matching daily energy intake to training load, particularly carbohydrate availability around key long runs and quality runs (speed, tempo, hills), is essential for keeping bone density up and tissue resilient!
4. Poor Sleep Quality
While total sleep hours matter, a 2025 prospective study by Goldberg et al. found that poor sleep quality was linked to a 36% higher risk of developing a running-related injury.
Interestingly, sleep quality predicted injury far better than total sleep duration alone.
The Recovery Connection
Sleep is the body’s primary anabolic state for tissue repair, hormone regulation (growth hormone release), and nervous system restoration. When sleep quality degrades:
Soft-tissue repair mechanisms slow down.
Perceived exertion (RPE) rises, making normal training paces feel significantly harder.
Morning muscle soreness and systemic fatigue build over the weeks leading up to an injury.
Clinical Takeaway
We know sleep is important, and we often chat with folks about how many hours they need. This study reinforces the need to also prioritize sleep hygiene.
Keep a consistent sleep schedule. Keep your sleeping environment cool and dark. Limit screens before bed.
You’ve heard it all before, but the evidence now shows just how big a difference it can make to your running goals.
If you notice a stretch of poor sleep quality, especially if it’s combined with more morning muscle soreness or heavy legs, treat it as an early warning sign to scale back intensity or take an extra recovery day.
5. Rapid Increases in Training Intensity & Pace
While total volume often gets the spotlight, abrupt jumps in high-intensity running (e.g., speedwork, tempo efforts, interval sessions, or hill repeats) carry a disproportionately high risk for tendon and muscular overload.
The Mechanics of Intensity
Higher running speeds dramatically increase peak ground reaction forces and the rate of force development. Tendons act like spring-loaded biological shock absorbers; while cardiovascular fitness adapts quickly to intensity, dense connective tissues (like the Achilles, patellar, and proximal hamstring tendons) adapt much more slowly. Rapidly introducing interval sessions or sudden pace jumps stresses these tissues faster than they can remodel.
Clinical Takeaway
Ensure that your tissue capacity is prepared to handle the increased demands of higher-intensity training by:
Introducing speedwork conservatively.
Increasing high-intensity exposure gradually. Starting with short strides or light hill surges before introducing full tempo or interval blocks.
Summary: A Current Approach to Injury Prevention
| Risk Factor | Current Evidence | Clinical Takeaway |
|---|---|---|
| 1. Previous Injury | Strongest overall predictor of future injury | Complete full rehabilitation; rebuild strength & tissue capacity beyond pain-free status. |
| 2. Single-Run Spikes | Single sessions exceeding 110% of 30-day max spike injury risk | Distribute volume across easy runs; cap individual long-run increases. |
| 3. Underfueling (REDs) | Impairs bone density, tissue repair, and neuromuscular function | Match caloric and carbohydrate intake to daily training demand. |
| 4. Poor Sleep Quality | Associated with a 36% higher risk of running injury | Focus on sleep hygiene; adjust training load when sleep quality drops consistently. |
| 5. Sudden Pace/Intensity Spikes | Creates rapid spikes in ground forces and tendon load | Introduce speedwork gradually; build tendon tolerance over time. |
The Bottom Line
Injury prevention is always multifactorial, meaning that no single factor is likely to cause injury. Instead, you need to manage load continuously, respect recovery physiology, and build a foundation that can handle the demands of your goals, while staying ready to adjust the plan as needed when life happens.
If you're navigating a persistent niggle, returning from a past injury, or looking for individualized gait and strength analysis to guide your next training block, The Runner’s Academy is here to help.
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If you’re looking for running physiotherapy or running chiropractic services and are located in Toronto or Hamilton, we’d love to chat all things running with you.
We specialize in understanding current best practices in treating running injuries across our clinic locations in Hamilton, Downtown Toronto, and Midtown Toronto.
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References:
Frandsen, J. D., Nielsen, R. O., Rasmussen, S., & Ramskov, D. (2025). Single-session volume spikes and running-related injury risk in 5,200 runners: A prospective cohort study. British Journal of Sports Medicine, 59(4), 215–223.
Goldberg, A., Stellingwerff, T., & Johnston, C. (2025). Subjective sleep quality, but not total sleep duration, predicts running-related injury risk in endurance athletes: A prospective investigation. Journal of Science and Medicine in Sport, 28(2), 112–118.
Mountjoy, M., Ackerman, K. E., Bailey, D. M., Burke, L. M., Constantini, N., Hackney, A. C., Heikura, I. A., Melin, A. K., Pensgaard, A. M., Stellingwerff, T., Sundgot-Borgen, J. K., Torstveit, M. K., Urdampilleta, A., & Verhagen, E. (2023). 2023 International Olympic Committee (IOC) consensus statement on Relative Energy Deficiency in Sport (REDs). British Journal of Sports Medicine, 57(17), 1073–1097. https://doi.org/10.1136/bjsports-2023-106994
van Poppel, D., van der Worp, M., Slabbekoorn, A., van den Heuvel, S. S. H., van Middelkoop, M., Koes, B. W., Verhagen, E. A. L. M., & Scholten-Peeters, G. G. M. (2021). Risk factors for running-related injuries: A systematic review and meta-analysis. Scandinavian Journal of Medicine & Science in Sports, 31(5), 985–998. https://doi.org/10.1111/sms.13914