Running injuries
Evidence: moderate
Around half of runners pick up an injury each year, and most are overuse injuries linked to how training load is applied rather than to running itself. The load-error framing is well supported; the evidence for specific preventive measures is thin, with strength training the clearest exception.
Not medical advice
This is a general knowledge base, not medical or dietary advice. If you are injured, unwell or weighing up a supplement or a change to your diet, speak to a doctor, physiotherapist or registered dietitian who knows your situation.
About 40 to 50% of runners sustain a running-related injury in a given year, and more than 70% of those injuries are overuse injuries rather than sudden traumatic ones (Kakouris et al. 2021). Roughly four in five injuries occur at or below the knee, with the knee, lower leg and ankle the most common sites (Kakouris et al. 2021). The injuries that stop most runners are not freak accidents. They are tissues that were loaded faster than they could adapt.
It is load, not running
Running does not wear the body out on its own. The repetitive loading of running is also the stimulus that makes bone, tendon and muscle stronger, as long as load and recovery stay in balance (see physiological adaptations). Overuse injury is what happens when that balance tips: load rises faster than the tissue adapts.
The clearest single trigger is a sudden spike in a single run. In a cohort of 5,205 runners across 588,071 sessions, running a distance more than 10% longer than the longest run of the previous 30 days raised the rate of overuse injury, and the risk climbed with the size of the spike, from a hazard rate ratio of about 1.6 for a small spike to 2.3 for a session more than double the recent long run (Johansen et al. 2025).
A single outsized run is a clearer trigger than the weekly total
In that same cohort, week-to-week mileage change and the popular acute:chronic workload ratio (ACWR) showed no positive association with injury (Johansen et al. 2025). This is one large cohort, and the ACWR is itself contested on methodological grounds, so read this as a reason to distrust rigid weekly-percentage rules rather than proof that accumulated load never matters. The robust, actionable signal is to avoid one wildly long run relative to recent training.
This reframes the old advice. The ‘10% rule’, which caps weekly mileage growth at 10%, has weak direct support: a cautious 10% weekly progression did not reliably protect novice runners, though very steep jumps above 30% did raise distance-related injuries (Nielsen et al. 2014). The honest summary is that progressing gradually is sound, but the specific 10% figure is lore rather than a tested threshold, and avoiding one wildly long run matters more than hitting a weekly percentage.
What actually prevents injury
The marketed prevention industry is large and the supporting evidence is small. Most measures sold to runners have not been shown in trials to prevent injury. The one strong exception is strength training.
A meta-analysis of 25 trials found that strength training cut overall sports injuries to under a third and overuse injuries by nearly half, with a dose-dependent effect (Lauersen et al. 2014). A later review reached the same conclusion and again found strength training superior to other approaches (Lauersen et al. 2018). These trials pooled mostly general-sport and military cohorts rather than runners, so the figure transfers by inference, but the mechanism is plausible: stronger muscle, tendon and bone tolerate repeated loading better. See strength training for runners.
Build the base, then add strength
Two levers have the best support: progress training load gradually while avoiding single-session spikes (see base building), and lift twice a week. Almost everything else marketed as injury prevention is unproven.
Stretching, by contrast, does not prevent overuse injury. The same meta-analysis found no benefit from stretching (relative risk 0.96) (Lauersen et al. 2014), and reviews specific to running reach the same verdict (Lauersen et al. 2018). Stretching may have other uses, but keeping runners healthy is not one the data supports. See stretching.
Response to a given training load varies a lot between runners, so the same programme injures one person and not another (see individual variation). Tracking how you feel under load is more useful than any universal rule; see training monitoring.
Pain rules and getting back
Most overuse injuries settle with relative rest and a graded return rather than complete rest. The aim is to keep loading the tissue at a level it can tolerate while it adapts, not to stop entirely and lose fitness (Warden et al. 2021).
A common pain-monitoring approach for soft-tissue injuries allows mild discomfort during and after loading, up to about 3 out of 10 on a pain scale, provided pain settles back to baseline by the next morning and does not climb week to week (Warden et al. 2021). Pain that rises during a run, lingers the next day, or worsens session on session is the signal to reduce load. Bone stress injuries are the exception and need a stricter, near-zero-pain rule; see bone stress injuries.
When to seek help
Sharp, localised bone pain, pain that worsens despite sensible load reduction, night pain, or any injury that fails to improve over two to three weeks warrants assessment by a clinician. The pages here describe the typical course; they do not replace diagnosis.