Speed & Agility – RFD, Impulse, and Stride Characteristics | CSCS Chapter 19

Speed and agility performance rely on the precise application of force, defined by impulse and the rate of force development (RFD). Athletes must optimize the force-time curve by increasing neural drive and leveraging the stretch-shortening cycle to enhance muscle stiffness and elastic energy recovery. While the spring-mass model effectively illustrates human locomotion, actual performance hinges on the interaction between stride length and stride frequency. Early speed gains often stem from increased stride length, whereas elite-level velocity improvements rely heavily on maximizing stride frequency. Effective agility requires not only explosive acceleration and deceleration but also superior trunk stability to reorient the center of mass in response to external stimuli. These biomechanical and neurophysiological factors provide the foundation for designing effective training interventions that improve both linear speed and complex change-of-direction maneuvers.