Effect of repeated testing on equine helmet impact attenuation

Objective To test equestrian helmets commonly used in the United States and determine the impact absorbing ability after multiple (4) impacts to the crown. Setting Laboratory. Patients or other participants Seven helmets were tested. Interventions A Cadex helmet drop tower was used to perform the testing. Impact velocities were measured using a calibrated Velocimeter (Time Gate) fixed to the drop tower. Impact acceleration measurements were obtained using a PCB Piezotronics accelerometer with Cadex Impact Setup software V 6.8. Main outcome measures Impact attenuation testing was performed on the helmets in accordance with ASTM F1163, dated 2013. No individual acceleration was to exceed 300 G (gravitational constant). The helmets were impacted four times on the crown location and were x-rayed before testing and after Impact No. 1 and 4. Results One helmet (a caliente style helmet) failed after one impact (> 923 G). Only one helmet passed ( 300 peak G for impacts 4 and 5. While 6 of the helmets met ASTM standards following 2 impacts, average increases in peak G were 15.9%–43.2% between the first and second impact. Conclusions Based on the results of this research, equine helmets should be replaced after an initial contact and most are incapable of meeting ASTM standards after two impacts. Caliente style helmets failed established guidelines after one impact and are not effective for reducing peak acceleration when compared to established standards. Competing interests None.