5K to Marathon: How to Build Up Safely (Mileage Progression Guide)
The jump from 5K fitness to marathon readiness is mostly about gradual mileage. A slow progression builds durability and reduces injury risk.
Simple Progression Rule
Increase weekly mileage by 5 to 10 percent every 2 to 3 weeks, then take a lighter week to absorb training.
Example Progression
- Weeks 1-4: 15 to 22 km per week
- Weeks 5-8: 22 to 30 km per week
- Weeks 9-12: 30 to 40 km per week
- Weeks 13-16: 40 to 55 km per week
Key Takeaway
Consistency beats speed of progression. Focus on time on feet and recovery, and add intensity only after the base is stable.