Preparing for your first 50K brings up one of the most common questions in ultramarathon training: How long does my long run really need to be? The short answer is: not as long as you might think — and, as always, it depends.
The challenge with ultra training is balancing two competing needs. On one hand, you must be prepared for the demands of the event. On the other, you need to avoid the classic pitfalls of doing too much: illness, injury, and burnout. Striking this balance is key.
Unlike training for shorter events, you typically cannot run the full race distance in training. For a half marathon, it’s common to build long runs up to 20–25 km. For a marathon, many runners feel confident once they’ve reached 32–35 km. But applying that same logic to a 50K can get you into trouble. Trying to run 45–55 km in training offers very little benefit and introduces a significant amount of risk. The only real upside is psychological, while the downsides are substantial: long recovery times, missed training due to fatigue, and a higher likelihood of injury or illness. Highly trained or elite runners can sometimes handle these distances in training, but most athletes cannot.
For the majority of runners, the length of a single peak long run matters far less than overall running fitness and consistency. What truly makes a difference is the cumulative work you’ve done in the 10–12 weeks leading up to the race, especially the number and quality of your long runs.
Ultimately, running your first ultramarathon always requires a leap of faith. You won’t go into race day having ever run the full distance, and that’s normal. Trust the training, trust the process, and embrace the challenge with confidence.
