Exposure data. Why are they needed?

Aspects of different approaches to study design in the epidemiology of sports injuries are presented, identifying 4 major types: (i) the clinical case series; (ii) the community-based survey; (iii) studies on specific sports or diagnoses without exposure data; and (iv) studies on specific sports or diagnoses with exposure data. The advantages and disadvantages of these concepts are discussed. It is concluded that to optimise preventive efforts and improve the comparability of studies in sports injury epidemiology, there is not only a need for consensus on definitional issues, but also for an agreement on the methodology. Attention to exposure issues is a crucial component of this.