Background Risk compensation theory has been used to explain why safety interventions in sport, such as personal protective equipment, are not as successful as predicted. As an example, it has been postulated that rugby union players wearing padded headgear may change their behaviour and tackle more forcefully because they perceive their injury risk to be reduced by headgear. Studies of risk compensation have often relied on self reported behaviour. In rugby football, players have reported that they can tackle harder and play more confidently while wearing headgear, however tackle force has not been measured.

Objective To assess risk compensating behaviour using a psycho-physical model.

Design A repeated measures design was applied to study the effect of wearing padded headgear on tackle force.

Setting Community level adult rugby union football.

Participants 98 players, mean age 25 years, participated in the study.

Intervention Standard padded headgear.

Main outcome measurements The force applied by the dominant shoulder was measured using an instrumented 45 kg tackle bag. Each participant completed six tackles. Demographic data and responses to standard surveys of risk perception were completed by each participant.

Results No significant difference was observed for tackle force with (mean=2025 N, SD=695 N) and without headgear (mean=1996, SD=728 N). No significant differences were observed for headgear use when examining effects of age, experience, risk propensity and belief regarding headgear effectiveness. A significant main effect of experience on tackle force was observed (p=0.029).

Conclusion Risk compensating behaviour may not be as prevalent as has been postulated and, in this context, self reported behaviour may not be a reliable guide to actual behaviour. Sports behaviours can be measured with appropriate psycho-physical methods. Closer scrutiny of the effectiveness of sports injury interventions is warranted and/or evidence of behavioural change.