The mechanical interactions between an American football cleat and playing surfacesin-situat loads and rates generated by elite athletes: a comparison of playing surfaces

Abstract

This study quantified the mechanical interactions between an American football cleat and eight surfaces used by professional American football teams. Loading conditions were applied with a custom-built testing apparatus designed to represent play-relevant maneuvers of elite athletes. Two natural grass and six infill artificial surfaces were tested with the cleated portion of a shoe intended for use on either surface type. In translation tests with a 2. 8-kN vertical load, the grass surfaces limited the horizontal force on the cleats by tearing. This tearing was not observed with the artificial surfaces, which allowed less motion and generated greater horizontal force (3.2 kN vs. 4.5 kN, p < 0.05). Similarly, rotation tests generated less angular displacement and greater torque on the artificial surfaces (145 N m vs. 197 N m, p < 0.05). Translation/drop tests, in which the foot-form was launched into the surfaces with both horizontal and vertical velocity components generated less peak horizontal force on the natural surfaces than on the artificial surfaces (2.4 kN vs. 3.0 kN, p < 0.05). These results suggest a force-limiting mechanism inherent to natural grass surfaces. Future work should consider implications of these findings for performance and injury risk and should evaluate the findings' sensitivity to cleat pattern and playing conditions.

Mutual and asynchronous anticipation and action in sports as globally competitive and locally coordinative dynamics

“…The difference in relative velocity and acceleration amplitude between the two outcomes in measured data ( Fig. 5C,D ) was probably derived from the attacker’s prediction to avoid bumping into the defender after the attacker’s prediction to fail in attack 24 , rather than from competition dynamics of the one attractor and divergence from the attractor. Specifically in determination phase to determine the outcome (see Methods and Fig.…”

“…Two competitive agents should abruptly change the whole two-agent system to achieve their objectives (e.g. escape 23 or attack 24 ) from the deadlock or skirmish situations which have been revealed in tag-play 21 and martial arts 20 22 . Nonlinear dynamics have also investigated bifurcation phenomena defined as discontinuous qualitative changes in a system caused by the continuous change of some control parameter (bifurcation parameters) 25 .…”

“…We previously focused on the one-on-one dribble in a ballgame 24 in which the roles of the attacker and defender were fixed and the outcome was determined as either a successful attack or defence ( Fig. 1A ).…”

“…1A ). Previous results have demonstrated that a defender’s better preparatory body state before taking the defensive step, which was defined as the maximum value of vertical ground reaction force ( Fz ) 28 , helps in preventing a delay of the defensive step initiation and promotes a successful defence 24 ( Fig. 1C , Video S2 , 3 ).…”

The University of the National Football League: How Technology, Injury Surveillance, and Health Care Have Improved the Safety of America's Game

“…The Foot and Ankle Subcommittee has performed multiple studies examining the mechanical interaction between football cleats and playing surfaces, 30 foot kinematics and loading during various football-specific tasks, 31 and the biomechanics of metatarsophalangeal joint ("turf toe") injuries. 32 This last example illustrates the practical application of their in vitro research that showed that most turf toe injuries occur when the first metatarsophalangeal joint dorsiflexes beyond 56 degrees.…”