Volunteers (986) from fitness clubs and studios were recruited and followed for a 3-month period to document the injury consequences of adult recreational fitness participation. Participants were telephoned each week and their activities as well as any injuries that occurred were recorded. Of the 525 injuries and complaints reported during 60,629 hours of activity, 475 occurred as a result of sports participation for an overall rate of 7.83 per 1000 hours of participation. Seventy-six percent of these episodes caused the patient to alter or miss 1 or more activities, while 9.5% involved a physician visit. The rate for time-loss injuries was less than 2 per person per year (1.76 per 298 hours) or 5.92 per 1000 hours. Running had a higher risk of injury compared with most other individual sports. Cardiovascular fitness activities had low to medium rates, as did weight work; competitive sports were higher. For 6 of the most commonly injured areas, the reinjury rate was about twice that reported for those with no history of previous injury. The risks of injury from most recreational fitness activities were relatively modest, particularly if the activities were not competitive. Physicians might help patients reduce their risks of injury by encouraging suitable activities and by reducing the risks of reinjury by implementing appropriate rehabilitation programs.