BACKGROUND: Fitness facilities provide an avenue to engage in physical activity, which is widely encouraged to improve health. However, there is risk of injury. This study aimed to identify the specific causes of injuries sustained at fitness facilities and the activity being participated in, to aid in the development of injury prevention strategies. METHODS: Analysis of routinely collected emergency department case-series data were obtained from July 1999 to June 2013. Fitness activity-related injury cases were identified from narratives of injury events, with narrative information recoded into cause of injury and activity at time of injury categories. Recoded data were then analysed. RESULTS: Overall, 2,873 cases were identified that specified the exact cause of injury associated with injuries that occurred at fitness facilities. Injuries due to overexertion were most common overall (36.2% of all cases), as well as the main cause of injuries related to general free weight activities (52.6% of this activity) and group exercise classes (35.9%). Crush injuries due to falling weights were common for all free weight activities. Falls and awkward landings were common causes of injuries during group exercise classes (28.5% and 25.8%, respectively). Trips and falls were common throughout facilities, as well as from cardiovascular equipment more specifically. CONCLUSIONS: Detailed information on the causes of injuries allows the development of injury prevention strategies for fitness facilities and fitness activities. Facilities should implement risk management strategies to reduce the risk of injuries in their clientele, based on the identified major causes of injury in this study.