Training alters joint power distributions during running in National Football League Draft Preparation Players

The aim of this study was to compare joint-specific contributions to total lower limb joint power during a speed run in American style football players before and after a 6-week National Football League (NFL) draft preparation camp. Fifty-two players performed one 5-second treadmill run at 5.5-6.5 m/s before and after camp. Speed was consistent between tests. Bilateral hip, knee, and ankle power generation (positive) and absorption (negative) were calculated from kinematics and kinetics using inverse dynamics. Negative total limb power decreased for both limbs, significantly for the left (Z = -2.113, p = .035, r = .30) due to significant decreases in negative ankle power bilaterally (left, Z = -1.967, p = .049, r = .27; right, Z = -2.623, p = .009, r = .36). The contribution of negative left hip power significantly increased (Z = -2.398, p = .016, r = .31). While no other significant changes in positive or negative joint-specific magnitudes or contributions occurred, there were general distal-to-proximal shifts in joint power contributions. Players appear to have adopted more energy efficient running through moderate joint-specific mechanistic training adaptations such as a reduction in ankle power absorption.