The Influence of Friction Between Football Helmet and Jersey Materials on Force: A Consideration for Sport Safety.
BACKGROUND
The pocketing effect of helmet padding helps to dissipate forces experienced by the head, but if the player's helmet remains stationary in an opponent's shoulder pads, the compressive force on the cervical spine may increase.


OBJECTIVE
To (1) measure the coefficient of static friction between different football helmet finishes and football jersey fabrics and (2) calculate the potential amount of force on a player's helmet due to the amount of friction present.


METHODS
Cross-sectional study.


METHODS
Laboratory.


METHODS
Helmets with different finishes and different football jersey fabrics.


METHODS
The coefficient of friction was determined for 2 helmet samples (glossy and matte), 3 football jerseys (collegiate, high school, and youth), and 3 types of jersey numbers (silkscreened, sublimated, and stitched on) using the TAPPI T 815 standard method. These measurements determined which helmet-to-helmet, helmet-to-jersey number, and helmet-to-jersey material combination resulted in the least amount of static friction.


RESULTS
The glossy helmet versus glossy helmet combination produced a greater amount of static friction than the other 2 helmet combinations (P = .013). The glossy helmet versus collegiate jersey combination produced a greater amount of static friction than the other helmet-to-jersey material combinations (P < .01). The glossy helmet versus silkscreened numbers combination produced a greater amount of static friction than the other helmet-to-jersey number combinations (P < .01).


CONCLUSIONS
The force of static friction experienced during collisions can be clinically relevant. Conditions with higher coefficients of static friction result in greater forces. In this study, the highest coefficient of friction (glossy helmet versus silkscreened number) could increase the forces on the player's helmet by 3553.88 N when compared with other helmet-to-jersey combinations. Our results indicate that the makeup of helmet and uniform materials may affect sport safety.
Athletic Training, Adrian College, MI.
Anthony M
AM
Rossi
Athletic Training, Adrian College, MI.
Tina L
TL
Claiborne
Athletic Training, Adrian College, MI.
Gregory B
GB
Thompson
Athletic Training, Adrian College, MI.
Stacey
S
Todaro
D000704:Analysis of Variance; D003430:Cross-Sectional Studies; D005538:Football / Q000293:injuries*; D017276:Friction; D006260:Head Protective Devices; D006801:Humans; D008422:Materials Testing; D055595:Mechanical Phenomena; D011481:Protective Clothing; D013124:Spinal Injuries / Q000517:prevention & control*
axial compression; cervical spine; epidemiology; football uniforms; pocketing effect; static friction