The concentric phase of jump training and many of the anchor drills in this portion of training that creates the most excitement for youth athletes. Live plays in basketball, volleyball and football do not utilize a full eccentric phase, it is the concentric moments that truly power the athletes’ movement. Movements like a rebound in basketball, a spike in Volleyball and the touch-down after a stride in a 40 yard sprint happen because an athlete has the ability to apply large amounts of force off the ground in a split second. Parisi coaches can design many types of drills that feature a short eccentric phase therefore emphasizing the concentric phase. Movements that promote stiffness and quick ground reaction will improve an athlete’s overall speed. Parisi coaches can in- struct their athletes to perform sled push or box jumps and hurdle jumps with a very short eccentric phase. This prevents the deep triple flexion and creates more pre-tension and rapid stiffness.
Other options are drills that focus on solely the concentric phase with absolutely no eccentric. The start in a sprint would be an example of this. Other drills can be regressed to take out the eccentrics phase totally. These types of concentric only drills will help athletes take the slack out of muscle that is critical to quick explosive force production. Slack exists in muscle, just as if you were to pull a tire with a rope. At first when you initially start to run, the tire does not move until all the slack is out of the rope. Your muscles and tendons work the same way. The ability to co-contract to create tension from strictly a concentric state is a critical element in athletic performance. Most athletic moves do not permit a large electric loading phase so athletes need to train their muscular, nervous and fascia systems to create tension and force quickly initiated by concentric movements by taking the slack out.
The below image shows how slack exists in; muscle, tendon, and fascia, and how is must be removed before maximum force can be generated.