Background. Fitness (FI) and swimming instructor (SI) are two different type of trainers that are usually employed in fitness centers and their profession is highly physically demanding because they have to practice while teaching. To date, data on occupational disorders in FI are limited and there is no information about SI. Therefore, the primary outcome of this study was an exploratory analysis of occupational disorders experienced by FI and SI employed in various fitness centers through a self-reported questionnaire, to provide first data on its prevalence. The secondary outcome was to assess fitness levels, workloads and perceived exertion during a typical working day of SI and FI in order to explore the possible factors associated with occupational disorders in these professional activities. Methods. An online cross-sectional survey addressing physical data, frequency, duration and time of class participation and self-reported occupational disorders was conducted among 435 subjects (FI=254; SI=179). Subsequently, 97 subjects (FI=57; SI=42), were enrolled to investigate physical fitness by maximal oxygen consumption ( O2max), and daily workload by heart rate (HR) and rating of perceived exertion (RPE). Results. A total of 621 musculoskeletal disorders and 521 of other disorders were included in the study with 157 and 155 participants that experienced 2 or more injuries during their career respectively. FI exhibited a higher prevalence of musculoskeletal injuries and SI experienced more upper respiratory tract infections. O2max ranged from 47.0±4.0 to 51.9±3.7 ml·kg-1·min-1, and no statistically significant differences between sex and instructor type was found. No statistical differences between instructor type in HRmean and HRmean/HRmax was found. According to sex, female SI displayed significantly higher HRmean and HRmean/HRmax (p=0.018, p=0.022, respectively) than female FI. Conclusions. In conclusion, FI and SI experienced a high prevalence of musculoskeletal and occupational disorders during their professional career. Moreover, data on FI and SI physical fitness and daily workload monitoring will help to set up guidelines regarding maximum weekly teaching load.