Purpose/Background:​ The purpose of this study was to investigate if the risk of injury declines with increasing weekly running volume before a marathon race.

Methods:​ The study was a retrospective cohort study on marathon finishers. Following a marathon, participants completed a web‐based questionnaire. The outcome of interest was a self‐reported running‐related injury. The injury had to be severe enough to cause a reduction in distance, speed, duration or frequency of running for at least 14 days. Primary exposure was self‐reported average weekly volume of running before the marathon categorized into below 30 km/week, 30 to 60 km/week, and above 60 km/week.

Results:​ A total of 68 of the 662 respondents sustained an injury. When adjusting for previous injury and previous marathons, the relative risk (RR) of suffering an injury rose by 2.02 [95% CI:​ 1.26;​ 3.24], p < 0.01, among runners with an average weekly training volume below 30 km/week compared with runners with an average weekly training volume of 30‐60 km/week. No significant differences were found between runners exceeding 60 km/week and runners running 30‐60 km/week (RR=1.13 [0.5;​2.8], p=0.80).

Conclusions:​ Runners may be advised to run a minimum of 30 km/week before a marathon to reduce their risk of running‐related injury.

Level of Evidence:​ 2b