The effect of rugby shoulder padding on peak impact force attenuation

Objective: The introduction of shoulder pads has coincided with a rise in shoulder impact injuries in the game of rugby. In this study, the effect of shoulder pads on impact force attenuation was quantified. Design: Four different commercially available shoulder pads were tested for material properties. Hard and soft objects were dropped from predetermined heights onto a force plate imparting peak impact forces of 500, 1000 and 1500 N. The pads were then placed on the plate and subjected to 10 repeated impacts for each pad and drop height. Setting: Institutional laboratory setting. Main outcome measurements: Peak force attenuation, expressed as the percentage reduction of peak force when compared with the no-pad condition, was calculated. Time to peak impact, expressed as the percentage increase of time to peak impact when compared with the no-pad condition, was calculated. Results: All pads were found to reduce peak impact force and increase time to peak impact. Results varied between 1% and 70%, depending on the drop height and properties of the impactor. The best performing pad was the thickest, and all pads were best able to attenuate force under hardobject impacts particularly for the lower loads. Conclusion: Although several limitations exist to laboratory-based studies such as these, the inconsistencies in force attenuation were nonetheless disappointing. The pads appear to "bottom out" under higher-impact loads and therefore offer little protection when the athlete may need it most.