NFL Draft Prep Players Improve 40-Yard Run Times and Foot-Ground Kinetics

Abstract

Introduction: Linear speed is a discriminant factor between drafted and undrafted American football players into the National Football League. Linear speed is influenced by foot-ground contact time and the magnitude of vertical ground reaction force. The aim of this study was to determine if foot-ground kinetics during speed running could be modified through participating in a 6-week NFL draft preparation camp. Methods: To evaluate foot-ground kinetics, 16 American football players ran on an instrumented treadmill for 5 seconds at 6.5 m/s. Linear speed was measured during a 40-yard (36.6 m) outdoor run. Pre- and post-camp linear speed times, stance-averaged vertical ground reaction forces (vGRF, kg/N), foot-ground contact time (msec), and vertical impulse (kg/N * s) were examined using paired t-tests, p<.05. Results: Linear speed times significantly improved [(pre, 4.8±0.2 vs. post, 4.6±0.2 sec), t(15)=13.8, p<.001)], and foot-ground contact time significantly decreased for the right limb [(pre, 177+3.2 vs. post, 168+2.2 ms), t(15)=2.21, p=.043]. Mean vertical impulse and stance-averaged GRF for both limbs remained unchanged, p>.05. Conclusions: Linear speed and selected foot-ground kinetics are modifiable in NFL draft prep players. Training appears to lower 40-yard run times and foot-ground contact time.