Exercise and sport participation is often promoted as a means of improving health and reducing the risk of illness. But exercise and sport undoubtedly pose their own health problems and little has been done to assess and quantify the factors that increase the risk of injury. Now rresearchers have taken a lead on such an exercise, prompted by the evidence that rugby is the largest contributor to sports injury costs borne by the country's mandatory injury compensation scheme.

The Rugby Injury and Performance Project (RIPP) was undertaken to examine a wide range of extrinsic (to do with the sport) and intrinsic (to do with the player) factors thought to be linked with rugby injury. At the beginning of the 1993 rugby season, 258 male rugby players were recruited into the study through rugby clubs and secondary school. After comprehensive anthropometric and fitness assessment, they were followed closely through the season to track their participation, their injury incidence rates and the proportion of the season lost through injury - the latter being a key measure of severity.

In terms of injury incidence, the key risk factors to emerge from the final analysis were:
grade - with players at the highest level sustaining the highest rate of injuries
previous injury experience, with players who reported a pre-season injury having a higher injury incidence rate than those who had no injuries during the previous season.

For time lost through injury, the key risk factors were:

• playing position - with midfield backs missing 21% of the season on average, compared with just 7% for inside backs
• body mass index (BMI) - with very slight players at greatest risk
• strenuous physical activity for more than 39 hours per week
• previous injury
• cigarette smoking status - with both ex-smokers and current smokers at increased risk.

The key message from the researchers focuses on the role of previous injury.'The results of the analysis of previous injury indicate that players who entered the season carrying an injury placed themselves at higher risk of both missing play and sustaining a higher injury incidence rate through the following season,' they point out.

'Thus returning to play before full recovery from injury may also place players who were otherwise fit at a higher risk of further injury. To reduce their risk of sustaining injuries and missing playing time, players should enter the rugby season injury free.'