Maximum Velocty When maximum velocity is achieved (within 30 to 60 m, depending on the athlete), the trunk position will be more upright(figure 12. 4), and the stride rate and length will both contribute to the velocity of movement. During th spent in the nonsupport p hase will be maximized by the application or s phase, the time rtical ground reaction forces during the initial support phase, allowing ufficient time for the swinging leg to be repositioned in preparation for the transition into the next support phase. Athletes who are able to appl higher horizontal ground reaction forces during the support phase of the maximum velocity portion of a sprint, though, are able to reach and maintain higher velocities of movement(18, 18b, 53, 71, 77, 82).This further strengthens the contention that strength and power training are essential components of a periodized training plan that emphasizes speed development As the athlete enters the support phase, he will contact the ground directly beneath his center of gravity. While moving into the support phase, the athlete will transition from an eccentric braking action into a concentric action with the use of an SSC action. During the concentric phase, the athlete will perform a"triple extension of the hip, knee,and ankle to properly apply forces against the ground. After the triple extension is performed, the athlete will then initiate a triple flexion of the ankle. knee, and hip, whIch will place the heel close to the buttocks At this point, the heel of the recovery leg will pass above the the knee (figure12.5).This triple flexion motion allows the athlete to rapidly move the knee to a position in front of the hip, effectively positioning the leg on the front side of the body. This movement prepares the foot for a rapid descent and allows the athlete to maximize ground reaction forces as the foot moves down and back during ground strike(87)