Javelin Mechanics THE GRIP. THE RUN-UP (first 6 steps)

May 3, 2017 | Author: Tabitha Sullivan | Category: N/A

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1 Javelin Mechanics In Javelin Throwing, you will see little difference in technique from one athlete to the difference ...

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Javelin Mechanics In Javelin Throwing, you will see little difference in technique from one athlete to the difference in technique from one athlete to the next. Some athletes will rotate the javelin arm forward, downward, and then extend it back prior to throwing. Others extend the throwing arm directly back without any forward motion. Some variations occur in the forward in the number of crossover steps that are used to tilt the throwers body backward so that it is in a good throwing position. Beyond these differences, the main elements of javelin technique are similar for all throwers. Each movement pattern in throwing the javelin contains some preparatory actions commonly called and approach. These actions help position the body and javelin in the optimal position for the application of force. The Run-up provides an additional distance over which the athlete is accelerated. Relaxation and flexibility help produce an optimal windup.

THE GRIP Javelin throwers try 3 grips. At LHS, we go with the most common grip called the Index-Finger Grip. The thrower's index-finger grips the javelin shaft to the rear of the binding. The throwers thumb lies along the side of the binding. The javelin lies in the center of the palm of the hand and is gripped by the thrower's fingers. If the other two grips want to be tried then the athlete can research and try them on their own.

THE RUN-UP (first 6 steps) For beginners, a 9-11 stride approach is recommended. Elite throwers frequently us a 25m-30m approach, in which 10-15 strides are devoted to a smooth acceleration into the throwing stance. Elite throwers will also use one or two check marks, the most important of which is commonly placed at the fifth stride prior to throwing. The beginning thrower needs to master the 5-stride throw before he/she adds the 4 strides needed to extend the javelin arm and enter the throwing stance. The additional 2 strides is needed at the beginning to accelerate the thrower from the start. At the beginning of the Run-Up, the thrower faces the direction of the throw with the shoulders and hips square to the front. As the thrower accelerates through the run-up the javelin points toward the direction of the throw with the tip slightly down. High-velocity throwing require the athlete to simulate the cracking of a whip. The high speed movement of a javelin throw will require the athlete to generate phenomenal velocity. This flail-like action is called a kinetic chain action because the slower motions produced in the athlete's longer, larger, and heavier limbs are made faster and quicker as they pass their motion on to lighter, less massive body parts. In these high-velocity throwing skills, there is a rapid acceleration of the thrower's body segments, beginning with those in contact with the earth. A whiplash, or flail-like, sequence progresses upward from the legs to the hips, from the hips to chest, and culminates in the tremendous velocity of the throwing arm. To achieve the greatest possible velocity, it is important that antagonist muscle groups are completely relaxed and the agonist muscles contract in sequence, helping to make each body segment move faster than the previous one. Too much velocity in the early part of the run-up may cause the thrower to slow down during the throwing actions or may not give the thrower enough time in the throwing stance to apply and

optimal amount of force to the javelin. Efficient use of a run-up can increase the distance thrown by 90-100 ft compared with a standing throw.

THE DRAW-BACK (7-9 step) On the 7th step, the thrower takes the javelin back to a full arm's length with the tip of the javelin now raise to the trajectory angle. The shoulders rotate 90 degrees to the right (right-handed throwers), and the hips remain facing the direction of throw. Rotating the shoulder girdle and extending the throwing arm prepare the thrower for the application of force to the javelin over the largest possible distance and time frame.

CROSS-STEP, CROSSOVER OR IMPULSE STEP (9th step) For a right-handed thrower, the cross-step is initiated by having the right leg stepping out and across in front of the left leg. This step helps to move the athlete's lower body ahead of the torso, tilting the athlete's body backward and away from the direction of throw. The thrower's shoulders and javelin arm are taken as far back as possible. The back ward body lean makes the distance and time frame mentioned before, even greater.

THROWING POSITION (10th step) The throwers left leg steps out into a wide throwing stance, with the heel contacting the ground prior to the rest of the foot. This step is usually larger than those prior. Stepping forward with the opposing foot sets up a large base of support for the application of force to the javelin. This allows the thrower's hips and shoulders to be rotated back toward the approach and away from the direction of throw. The thrower's rear leg (right) is partially flexed at the knee and turned out to the side, 45 degrees from the direction of the throw. Flexing the rear leg stretches the leg muscles in preparation for their explosive rotary thrust toward the direction of throw. This rotary motion is the first stage in the thrower's whiplash action that starts from the thrower's base and progresses up to the throwing arm.

THE THROW (Initial Phases) More massive, slower moving parts of the body shift forward into the throw while lighter body segments (e.g. the throwing arm) complete their backward extension. This motion stretches the muscles in the abdomen, chest, and shoulders, getting them ready for their explosive contraction during the later phases of the throw. Meanwhile, the rear leg is vigorously rotated toward the direction of throw. This action thrusts the hips in the same direction. The muscles joining the hips to the torso stretch and contract explosively. The thrower's torso rotates and pulls the shoulders and the throwing arm toward the direction of the throw. Opposing muscle groups are relaxed. As the shoulders are pulled forward, the muscles of the shoulders stretch and then contract vigorously. Each of the thrower's body segments, from the legs through to the shoulders and throwing arm, sequentially accelerates. This sequence sets up a flail-like whip cracking action that progressively builds and ends in the tremendous velocity of the throwing arm. The thrower's body tilts sideways, away from the throwing arm. This sideways inclination of the thrower's torso allows for greater height of release. The free arm rotates backward to help pull the chest and throwing arm around and into the throw. This helps rotate the thrower's torso around the long axis of the body. Rotation of the torso makes a contribution in pulling the throwing arm at high velocity into the throw.

THE THROW (final phases) As the athlete's throwing arm is pulled forward, the upper arm and elbow lead, with the throwing hand and javelin trailing well behind. Flexion occurs at the elbow of the throwing arm. This serves two purposes: (1)It helps the athlete become even more whiplike, and (2) the elbow acts like the axle of a whell with the throwing hand rotating around at it's rim. this wheel-axle arrangement increases the velocity of the throwing hand and the javelin. The thrower's body is pushed forward, up, and over a straight left leg, and the javelin is released in front of the thrower's head.

THE REVERSE The thrower thrusts forward toward the direction of throw. The torso moves forward beyond the supporting leg, which has been straightened. Forcefully driving the body as far as possible toward the direction of throw extends the application of force to the javelin over the longest possible distance and time period. After the javelin is released, the thrower continues to move forward, bringing the right leg forward and placing it in front of the left. This reverse step, arrests any further

motion and stops the athlete from stepping over the foul line. Additionally, the follow-through allows for a safe dissipation of momentum from the athlete's body.

THE RELEASE The angle of release of the javelin varies according to the throwing ability of the athlete, the type of javelin used, and environmental conditions at the time of throwing. A javelin is dramatically affected by lift and drag forces. A moderate headwind of 5-10 mph provides excellent lift to the javelin because it pushes up on the "undersurface" of the javelin. A tailwind is detrimental because it pushes down on the upper surface of the javelin.

In Summary In the force-producing phase of a javelin throw (last 5 steps), the athlete makes his/her approach, leans back, and steps forward into a wide throwing position. He/she then rotates his/her hips and chest toward the direction of throw. Simultaneously, the athlete shifts his/her body weight from the rear to the forward leg. Key elements: Run-up approach, backward lean, wide throwing stance, hip and chest rotation, weight shift.