What is the 3-week rule and why should anyone training for a marathon know about it?

07 Mar 2023

A study of 784 runners training for a half marathon has concluded that training load, specifically mileage and pace, are dominant factors in causing running-related injuries. The majority of running plans roughly follow the 10 per cent rule – upping your mileage by no more than 10 per cent each week – but there is an alternative method that’s worth a try – it may even reduce your injury risk.

In his new book, Fast 5K, (VeloPress), running coach Pete Magill recommends the three-week rule. This advises that you give your body three weeks to adapt to each jump in volume and intensity. This allows you to schedule regular, balanced increases with a decreased risk of injury. As Magill writes: ‘For low-volume runners, the 10 per cent rule creates mileage increases that are well below the body’s ability to adapt,’ he writes. ‘For higher volume runners, the 10 per cent rule leads to increases that are likely to produce injury or burnout. The three-week rule is more physiologically sound.’

Source: runnerworld.com