Kinetic Link Analysis

Science of the Kinetic Link

Kinetic link analysis

Comparison of players to elite hitters allow players strengths and weaknesses to be quantified and modified:
The best hitters consistently utilize almost identical mechanics to maximize the swing performance by maximizing the physical elements of the kinetic link

Kinetic analysis identify common mechanics used by elite hitters as follows:
Phase 1 – Separation
• 1. Measure: Substantial increase in the separation between the lower half of the body and the upper half of the body

– as the center of mass is pushed forward by the back leg, the distance between the hands and the back knee increases
– this extension is fluid and unforced
– this may be the hitter’s single most important factor for the hitter to be able to hit at the elite level
– the lower and upper body separation tremendously effects the stretch reflex also known as the rubber band effect. The separation of the hands and lower body creates a rapid rate of stretch. The faster the rate of stretch, the more energy created. It also causes the muscles to snap back or shorten rapidly. The short time between stretch and snap back of short muscle increases the amount of energy that is used

• Moving the hands back as the bottom half pushed forward is responsible for elite level body segment separation
• The hips are pushed into rotation well before the smaller segments of the shoulders, arms and hands
• the segments are rotating at different times because of the body separation

Phase 2 – Back foot/leg push forward

• 1. Measure: Increase in separation between the upper and lower half as the center of mass is pushed forward

• Characteristic: An increase in the distance between the hands and the back knee as the center of mass is pushed forward

-Poor separation between hands and back knee will slow bat speed and power production
-Elite hitters will have sequential separation of body parts whereas non-elite hitters will move body parts simultaneously

• 2. Measure: The effectiveness of the “back foot/leg push forward” before the front foot/leg blocks the body’s forward momentum

• Characteristic: The back half of the back foot lifts up before the front leg blocks the body’s forward momentum (aversion of the back ankle)

-The action on the back foot promotes a smooth and timely transition to the front side
-If the timing is correct, the hips will thrust forward and begin rotation after the block and before the other segments of the body including the shoulders and the hands begin to rotate

• 3. Measure: The effectiveness of the back foot/leg push forward before the front foot/leg blocks the body’s forward momentum

• Characteristic: The back knee will initiate internal rotation before the front foot/leg blocks the body’s forward momentum

• 4. Measure: The effectiveness of the back foot/leg push forward before the front leg blocks the body’s forward momentum

• Characteristic: The back foot will come up on the toes, slide along the ground or come off the ground completely before contact to provide evidence that the center of pressure has shifted completely to the front foot

-Back foot comes off the ground or slides before contact with the ball
-Back foot comes up because of the forward momentum created by the back leg and the resulting rotation of the hips

Phase 3 – Front foot/leg Block
• 1. Measurement: Positioning of the front foot to promote effective momentum transfer and hip rotation as the front foot/leg blocks the body’s forward momentum

• Characteristic: The front knee exhibits significant flexion upon blocking the body’s forward momentum. Front knee extension should occur with hip rotation

-The flexed knee upon landing of the front foot allows the elite hitter to absorb and then transfer the body’s forward momentum
-The front leg is angled back meaning the front knee is behind the front foot and the front hip is behind the front knee.
-The front knee is flexed when the front foot lands
-A flexed front knee at landing allows the elite hitter to continue to apply force to the ground by extending at the knee and accelerating in the hips
-Front leg extension should occur only with hip rotation

• 2. Measurement: Extension of the lead arm as the front foot/leg blocks the body’s forward momentum. This lead arm extension promotes an effective stretch reflex and body segment separation

• Characteristic: The lead arm exhibits significant extension (>145 degrees) as the front foot/leg blocks the body’s forward momentum

-Early lead arm extension as the front foot drops and blocks the body’s forward momentum
-This lead arm extension is vital to the kinetic link because it increases the stretch reflex and it puts the hands back as the last part of the kinetic link
-Many elite hitters approach 160 degrees of extension in the lead arm as the front foot/leg blocks before shoulder rotation

• 3. Measurement: Stabilization of the head and the body’s center of mass as the front leg blocks the body’s forward momentum. The represents an efficient conversion of linear momentum into rotational momentum

• Characteristic: All forward movement of the head and the body’s center of mass should end as the front foot/leg blocks

-The front foot is placed significantly in front of the body’s center of mass.
-The increases the leverage and force of the subsequent push.
-The head and center of mass stabilizes as the front foot continues to push with the bending of the front knee to extension of knee with hip rotation
-This strong block without drifting forward represents an efficient conversion of linear to rotation with minimal energy leakage. Any drifting after the block will represent energy leakage

Note: The human body passes energy like a bull whip. Imagine the legs and lower half of the body being the hands and handle of the bull whip generating a forward momentum. Suddenly the hands and handle stop. When the handle stops the momentum is passed to the other segments of the bull whip. In the hitters case, the momentum would pass to the other segments of the human body. Momentum is passed from rotating body segment to rotating body segment. And like the bull whip, as the segments get smaller they pick up speed until all of the momentum is held in the tip of the whip or in the hitter’s case the hands and the bat

Instructional tips:
Ask the batter to attack the pitch with his legs. Take the inside part of the back knee to the ball as the hitter’s first movement at the ball. This will usually improve the timing and force of that push to the front side. This will often get the hitter’s mind off of the hands and arms and allow the hitter to leave those back lagging behind as the last part of the kinetic link.
Relaxing the upper body will help create greater lead arm extension and therefore create greater separation when the back leg pushes to the front side.