BackgroundDietary supplements (DS) may be beneficial for athletes in certain situations, whereas incorrect or excessive use may impair performance, pose a risk to the athlete's health and cause positive doping tests by containing prohibited substances. To provide athletes with relevant and tailored information on safe supplement use, a better knowledge about DS trends over time and between sport disciplines are needed.MethodsThis study examines the use of DS among athletes who have participated in doping controls by extracting information derived from 10,418 doping control forms (DCF) collected by Anti-Doping Norway from 2015 to 2019.ResultsOverall, 51% of the DCFs contained information about at least one DS. National level athletes (NLA) more often reported using DS than recreational athletes (RA) (53 vs. 47%, p < 0.001). Athletes in strength and power (71%), VO2max endurance (56%) and muscular endurance sports (55%) had the highest proportion of DCFs with information about DS. Medical supplements were the most used supplement category for both genders and across all sports. Dietary supplements with a high risk of containing doping substances were most common among male, RA in strength and power sports. There were small and non-significant year-to-year variations in the prevalence of athletes using DS, while the number of products used concomitantly peaked in 2017 before declining in 2019 (2.30 vs. 2.08, p < 0.01). The use of medical supplements and ergogenic substances increased slightly for both NLA and RA from 2015 to 2019, while the use of all other supplement categories declined.ConclusionHalf of the 10,418 DCFs contained information about DS, with variations within the athlete population. DS with high risk of containing prohibited substances were mostly seen in sport disciplines requiring a high degree of specialization in strength/power, including powerlifting and weightlifting, as well as in some team sports, such as cheerleading and american football.

The hematological module of the Athlete Biological Passport (ABP) aims to reveal blood doping indirectly by looking at selected biomarkers of doping over time. For Anti-Doping Organizations (ADOs), the ABP is a vital tool in the fight against doping in sports through improved target testing and analysis, investigations, deterrence, and as indirect evidence for use of prohibited methods or substances. The physiological characteristics of sport disciplines is an important risk factor in the overall risk assessment and when implementing the hematological module. Sharing of experiences with implementing the hematological ABP between ADOs is key to further strengthen and extend its use. In this study, we present 10 years of experience with the hematological ABP program from the perspectives of a National ADO with special attention to sport disciplines' physiological characteristics as a potential risk factor for blood doping. Not surprisingly, most samples were collected in sport disciplines where the aerobic capacity is vital for performance. The study highlights strengths in Anti-Doping Norway's testing program but also areas that could be improved. For example, it was shown that samples were collected both in and out of season in a subset of the data material that included three popular sports in Norway (Cross-Country Skiing, Nordic Combined, and Biathlon), however, from the total data material it was clear that athletes were more likely to be tested out of competition and on certain days of the week and times of the day. The use of doping control officers with a flexible time schedule and testing outside an athlete's 60 min time-slot could help with a more even distribution during the week and day, and thus reduce the predictability of testing. In addition to promoting a discussion on testing strategies, the study can be used as a starting point for other ADOs on how to examine their own testing program.