Background The risk of running injuries in novice runners is 17.8 (16.7–19.1) per 1000 h of running (Videbæk 2015). This might lead to the conclusion that running injuries are one of the main reasons for discontinued running. However the impact of running injuries in relation to other reasons for discontinued running remains to be investigated.

Objective To investigate the proportion of novice runners that sustained an injury before discontinuing running.

Design Observational prospective cohort study with a 1-year follow-up.

Setting Novice runners.

Participants 930 healthy novice runners, age 18–65, with less than 10 km of total running volume during the past year and no injury in the lower extremities or back 3 months preceding baseline.

Interventions The participants were equipped with a GPS watch and running shoes and instructed to upload their running to a web-based diary during the 1-year follow-up. They could keep the shoes and watch if they completed a total of 52 training sessions or more.

Main Outcome Measurements Discontinued running dichotomized (i) yes still running (ii) no training uploads for the remainder of the 1 year follow up (defined after data collection began), whereas the latter, was further dichotomized into (i) injured (a priori defined as 1 week time loss definition) (ii) injury free.

Results A total of 9% (7%–11%) had discontinued running after 90 days. Of these, 20% (11%–29%) had sustained a running injury. After 180 days the proportion discontinuing rose to 16% (14%–18%). Amongst these 16%, injured accounted for 24% (17%–31%). Finally, after 270 days the proportion who discontinued was 27% (24%–30%), with an injury proportion of 23% (18%–28%).

Conclusions Running injuries are common in novice runners who discontinue running. The developments of injury prevention strategies are important if more inactive persons should be successfully included in running.