One overly ambitious run is enough
Over 18 months, researchers followed 5,205 recreational runners, automatically collecting their training data through Garmin GPS watches1. The goal was to understand which increases in distance were most likely to lead to overuse injuries (tendinitis, shin splints, joint pain, etc.).
The results are clear: a single session with a distance increase of more than 10% compared to the longest run of the past 30 days significantly raises the risk of injury.
Observed increases:
- 64% higher risk for a 10-30% increase
- 52% higher risk for a 30-100% increase
- 128% higher risk if the distance is doubled or more
In contrast, variations in training load analyzed on a weekly basis were not significantly associated with increased risk in this study.
Toward a new paradigm: the single session
These findings challenge traditional approaches to training load monitoring. Instead of focusing solely on weekly volume, it becomes essential to track sudden increases in individual sessions.
In running, overuse injuries often appear without warning signs. This reinforces the idea that sudden spikes in load are more problematic than gradual week-to-week variations.
Practical recommendations for runners
Here are some principles to integrate into your training plans to reduce injury risk:
1. Limit distance increases in a single run
Avoid increasing your distance by more than 10% compared to your longest run in the past 30 days. For example: if your longest run was 10 km, don’t exceed 11 km in your next long run.
2. Spread volume increases across several sessions
It’s better to gradually add volume over multiple runs rather than making a big leap in one session. Even modest progressions (for example 11 km, then 12.1 km, then 13.3 km in the same week) can accumulate quickly and raise injury risk.
3. Include recovery days
Alternate training days with lighter or full rest days to allow your body to adapt gradually to new loads.
4. Listen to your body
Persistent pain, unusual fatigue, or declining performance should be taken seriously. It’s better to adjust your training than to risk a long interruption due to injury.
The perspective of Jean-Maxime, sports physiotherapist
This study highlights an important concept in running training planning. A sudden increase in distance during a single run can cause an injury — a frequent reason for consultation in sports physiotherapy.
While the overall message of the study is relevant, its statistics cannot be applied directly to every runner. Several confounding variables must be considered, as they can influence outcomes. For example, weight, age, sex, and training history are independent factors affecting one’s ability to increase training volume. Similarly, dependent variables such as nutrition, sleep, work or study schedules, and psychological state also influence one’s capacity to safely handle longer distances.
It therefore remains essential to consult a professional who can assess each runner’s abilities and goals to develop a safe and personalized training program.
At PhysioExtra, we support runners of all levels in their progress. If you’ve experienced an injury or want to structure your training safely, our professionals can help you reach your goals while minimizing risks. Learn more about our running assessment service.
1 Study source: Schuster Brandt Frandsen J. et al. “How much running is too much? Identifying high-risk running sessions in a 5200-person cohort study,” *British Journal of Sports Medicine*, 2025. [Online]: https://doi.org/10.1136/bjsports-2024-109380
