Running & Training What is the 80% rule in running? February 2, 2026 by Mercier | Leave a Comment The 80% rule in running is a training principle suggesting that 80% of your running should be at a low intensity, while the remaining 20% can be at a higher intensity. This approach helps runners improve endurance, reduce injury risk, and enhance overall performance by balancing training loads. What is the 80% Rule in Running? […] Read more ยป