Objectives To evaluate whether in fitness-related activities and recreational running over time, there is an increase in the number of novice sports athletes and whether these novice athletes have an increased injury rate compared with their experienced counterparts. Methods Data were collected from a large population-based retrospective cross-sectional study, € Injuries and Physical Activity in the Netherlands' (IPAN). Athletes aged ≥18 years were included. We used descriptive statistics to describe the characteristics of athletes and their injuries. The number of athletes and injuries were calculated for each year and, where applicable, for each sport separately. The injury incidence rate was expressed as the number of injuries per 1000 hours of exposure. Logistic regression analyses were performed with non-extrapolated data to analyse the differences in injury risk for novice and experienced athletes included in this study, separate for fitness-related activities and running. Results Over the 5 years, 9209 fitness athletes reported 370 fitness-related injuries, 5426 runners reported 537 running-related injuries. Weighted data showed that, in 2010-2014, the inflow of novice fitness athletes slightly decreased, whereas the inflow of novice runners slightly increased. In each year, injury risk was higher in novice athletes compared with experienced athletes for both fitness-related activities and running. The injury incidence rates in running are much higher than in fitness-related activities. Conclusions Over the years 2010-2014, the absolute number of novice athletes in fitness-related activities and running together increased. Although most injuries occurred in experienced athletes, injury risk was higher in novice athletes in both sports.