Biomechanical Concerns. When we look at lower body activity in the throwing events, we are concerned with three realms. They are blocking, lengthening the implement’s path, and force production.
Blocking. Blocking refers to a stopping or abrupt deceleration of the thrower’s movement. This fosters a transfer of momentum to the implement and establishes a stable position and stance from which to throw. There are two key blocks that occur in the lower body.
- The Front Leg Block. The front foot at delivery is planted roughly in the throwing direction. This places the front leg in position to decelerate the body’s forward momentum. A stable base is established from which to throw. The momentum of the implement is preserved as it continues forward, much in the same way as items fly off of the front seat of your car when you hit the brakes hard.
- The Hip Block. The hips turn as the throw is executed, but the turning of the hips must come to a stop as they reach a position facing the throwing direction. This provides a stable platform from which the upper body can operate to finish the throw. This block doesn’t result from an attempted deceleration, but is actually anatomical and results from proper body positioning and the way the hip is built, as we shall see shortly.
- Technical Points – Blocking
- Heel – Ball Stance. Generally, a heel-ball alignment of the feet should be used in the delivery position. This means that the heel of the rear foot and the ball of the front foot should lie on a line marking the direction of the throw. This positioning of the front foot places it in position to check momentum and establish a sound Front Leg Block. Its slightly offset position allows the hips to rotate more freely than if the feet were perfectly in line with each other.
- The Grind. The Grind gets its name from the grinding of the front foot against the surface as it grounds during the early part of the delivery. As delivery begins, the front foot contacts the ground on the inside ball of the foot, and the foot is pointed about 90 degrees from the throwing direction. The turning of the hips and leg turn and ground the foot, so that when it is planted solidly, it is pointed across the body at about a 40 degree angle to the throwing direction (roughly along the right sector line for a right hander). Isolating this movement in throwing drills is an important part of developing good throwing habits and mechanics. The javelin throw is an exception and does not show a Grind due to the higher velocities, but standing javelin throws and low speed javelin drills should show the same movements and finishing positions.
- Front Foot. This 40 degree/across the body position of the front foot as it grounds is critical. Because of the anatomical structure of the hip, this foot alignment forces the hips to stop turning when facing the throwing direction, establishing the Hip Block. Pointing the front foot in the throwing direction is a common error and coaching misconception. It allows the hips to turn too far and energy can’t be transmitted to the upper body effectively.
- The Rear Foot. As delivery is initiated, the back foot should be directed about 90 degrees from the direction of the throw. This enables the hips to turn properly.
- Foot Spacing. The feet should be spaced so that when weight is completely on the rear foot, the front leg is extended, nearly straight. This optimizes lengthening of the implement’s path.
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Lengthening the Path of the Implement. When throwing, we are trying to produce the greatest possible positive changes in velocity and momentum of the implement. To allow this, we try to maximize the length of the implement’s path during delivery. The farther the implement travels while still in the hand, the more time is available to accelerate it.
- Lengthening the Implements Path – Weight Transfer. During the delivery, bodyweight is transferred from the back foot to the front foot, increasing the length of the implement’s path. This weight transfer must be complete.
- Lengthening the Implement’s Path – Closed Hips. During the delivery, we wish to lengthen not only the linear path of the implement, but also the rotational path of the implement. For this reason, we begin the throw with the hips closed. Closed hips mean that as delivery begins, the hips are directed away from the throwing direction. These closed positions provide a greater angle through which the hips may turn before reaching their final position, and thus a longer time of force application.
- Technical Points – Lengthening the Implement’s Path. Technical teaching points regarding the length of the implement’s path center about teaching proper weight distribution and proper hip alignment. Each delivery must begin with all bodyweight on the rear foot, and finish with all bodyweight on the front foot. Our teaching and tapping progressions are designed simply to assure this proper weight distribution at all times. The shot put and discus events show hips directed about 90 degrees from the throwing direction when the delivery begins, while the javelin shows hips at 45 degrees.
- Weight Transfer. The transfer of weight we mentioned in the throwing events increases force production by lengthening the implement’s path and accelerating the implement directly.
- Turning. During the delivery, the hips should turn smoothly and progressively to a position facing the direction of the throw. This turning also takes advantage of a longer path of the implement, accelerating the implement directly.
- Lifting. During delivery, extension of the legs produces a vertical force to the implement. Integration of vertical force generation from the legs and horizontal force application from the strike during delivery should be created in unison and with correct timing.
- Technical Points – Force Production
- Pushing vs. Turning. The involved muscle groups are capable of pushing or rotation, but not both simultaneously. Teaching progressions must be set in a way that fosters turning of the hips. Many progressions are faulty, resulting in rear legs that push and destroy the rotational components of the throw.
- Rates of Transfer and Turning. The turning and weight transfer movements during delivery should occur simultaneously, and at similar rates. Transferring then turning, or vice versa, produce a very inefficient arrangement.
- Torque. The throw is initiated by turning the lower body, and the turning of the upper body lags behind slightly. This turning of the lower body, combined with the passiveness of the upper body, creates a twisting of the core of the body called torque. This torque creates stretch reflexes in the torso musculature, enabling greater subsequent acceleration of the implement as the core unwinds. This is the method by which rotational energy of the lower body is fed to the upper body.
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