New Research Reveals Running Injuries Occur Unexpectedly, Not Over Time

A groundbreaking study from Aarhus University has revolutionized our understanding of how running-related injuries develop. Contrary to the long-held belief that overuse injuries in runners gradually worsen over an extended period, this extensive research demonstrates that many injuries happen suddenly—often during a single training session. The study, published in the British Journal of Sports Medicine, involved tracking 5,205 runners from 87 countries over an 18-month period. Findings reveal that injury risk surges exponentially when runners increase their training distance beyond their usual maximum, particularly if they push significantly further than their recent long runs. This indicates that improper training behaviors in a single session, such as sudden increases in distance, are more significant contributors to injuries than previously thought.

Associate Professor Rasmus Nielsen explained that this study marks a paradigm shift in understanding overuse injuries. Instead of developing gradually, many injuries are caused by a runner’s mistake in a single training session, which can lead to immediate injury. This insight challenges current practices, especially the widespread use of training apps and sports watches that rely on weak scientific evidence to guide injury prevention. The commonly used algorithm, the 'Acute:Chronic Workload Ratio' (ACWR), introduced in 2016, calculates injury risk based on a ratio of recent to past training loads. It recommends not exceeding a 20% increase in training volume. However, Nielsen criticizes this approach, stating that it was developed from a small-scale study with minimal scientific backing and is generally misapplied to running without solid evidence.

In response, the research team has spent the last eight years developing a new, more accurate algorithm to prevent injuries in runners. Unlike previous methods, this new tool aims to offer real-time guidance, allowing runners to be alerted during a session if their training intensity or distance poses a high injury risk—similar to a traffic light system indicating green for low risk, yellow for moderate, and red for high risk. This initiative is intended to be freely accessible to athletes, coaches, and health professionals, with the hope that it will be integrated into existing wearable technology to enhance training safety.

Overall, this research emphasizes that sudden increases in training load are more dangerous than gradual buildup, highlighting the importance of cautious and informed training practices to prevent injuries. It urges sports technology developers and trainers to reconsider current injury prevention strategies based on more robust scientific evidence.