Objective To analyse the frequency and characteristics of sports injuries and illnesses incurred during the World Athletics Championships.

Design Prospective recording of newly occurred injuries and illnesses.

Setting Twelfth International Association of Athletics Federations World Championships in Athletics 2009 in Berlin, Germany.

Participants National team physicians and physiotherapists and 1979 accredited athletes; Local Organising Committee physicians working in the Medical Centres.

Main outcome measures Incidence and characteristics of newly incurred injuries and illnesses.

Results 236 injury incidents with 262 injured body parts and 269 different injury types were reported, representing an incidence of 135.4 injuries per 1000 registered athletes. Eighty percent affected the lower extremity. Thigh strain (13.8%) was the main diagnosis. Overuse (44.1%) was the predominant cause. Most injuries were incurred during competition (85.9%). About 43.8% of all injury events were expected to result in time-loss. 135 illnesses were reported, signifying an incidence of 68.2 per 1000 registered athletes. Upper respiratory tract infection was the most common condition (30.4%) and infection was the most frequent cause (32.6%). The incidence of injury and illnesses varied substantially among the events.

Conclusion The risk of injury varied with each discipline. Preventive measures should be specific and focused on minimising the potential for overuse. Attention should be paid to ensure adequate rehabilitation of previous injuries. The addition of the illness part to the injury surveillance system proved to be feasible. As most illnesses were caused by infection of the respiratory tract or were environmentally related, preventive interventions should focus on decreasing the risk of transmission, appropriate event scheduling and heat acclimatisation.