Unlocking the Secrets to Training the Kinetic Chain

by JJ Krutsinger, DPT
Physical Therapist
University of Colorado Health-Poudre Valley Hospital 

Strength training in your torso and hips greatly influences power and velocity in your arms and legs. This relationship between your torso and your limbs is known as the "kinetic chain." Read this guest blog by our former intern for tips on how to snap your core into shape to gain greater power throughout your body. 

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Want to throw the baseball harder, swim faster, or hit a volleyball harder?  The following read will not only give you another reason to get that beach body 6-pack, but it will also enlighten you on the importance of having good core strength to improve your performance.
 
Lets say a baseball pitcher wants to throw the ball faster.  The pitcher figures that lifting weights and increasing his arm strength will get him there.  This pitcher already understands the importance of having a strong arm for pitching, but he is leaving out a few other strategies that can also help increase his pitching speed.  A couple of these strategies are working on his pitching mechanics and increasing his abdominal strength.  

​In a journal article by Shane Seroyer and colleagues called, The Kinetic Chain In Overhand Pitching:  It’s Potential Role For Performance Enhancement And Injury Prevention, they explain how the arm is not the only body part playing a role in pitching but that both the legs and core muscles contribute to increasing the speed of the pitch.  The article further explains how we need to visualize the body as a chain with many links.  To keep it simple, lets say there are 3 major links.  The bottom link being the legs, the middle link being the core muscles, and the last one being the arms.  If we can incorporate each link in a pitch along with the proper body mechanics we can significantly increase the speed of the pitch. 

The kinetic chain of a pitcher extends from his arm, through the torso, to his legs

The "Reverse C" position shows eccentric contraction of muscles in the torso

One of the phases during a pitch is the cocking phase.  Lets take this phase in pitching a bit further. As part of the cocking phase, a pitcher creates a catapult with his body by extending his torso and drawing his arm back into a “Reverse C” position.  This “Reverse C” is reminiscent of a drawn-back catapult.  I’m not going to say I have flung a meatball across the table using a spoon, but this pitcher reminds me of flinging food.  When one bends that spoon far enough back, tension is created throughout the handle.  Once the spoon is released and the catapult swings forward, the meatball is released with incredible velocity, just like the ball coming out of a pitcher’s hand.  ​

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The middle section of the catapult represents the core muscles of the pitcher.  When you bend the catapult back, the middle section must be strong enough to withstand the tension of the bend without breaking the launcher.  Once the to is released, the middle section needs to be able to fling forward quick enough to get the meatball to go the distance. ​

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As the torso bends, stored energy is released, creating greater velocity into the arm

You can train your core muscles to respond to this "flinging" type of movement.  When you extend your torso backwards, your abdominal muscles elongate and fire in a controlled manner.  This is called an eccentric muscle contraction.  This is different from a concentric contraction where you fire your muscle and the muscle shortens.  When your core muscles are eccentrically loaded, like in the "Reverse C" picture, they store tension similar to when you draw the spoon back before the meatball launches. When you release the top of the spoon, just as a pitcher starts to fling his arm forward, that tension is released and the muscles fire concentrically. This eccentric load and release creates more velocity into the arm than a simple concentric contraction.  That velocity is seen in the form of a pitcher’s ball speed. ​

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A similar "Reverse C" mechanism is used in volleyball hitting

Now lets take this concept and apply it to other sports like volleyball and swimming.  For volleyball, when you serve or spike a ball you first bring your arm back and extend your torso with a controlled eccentric muscle contraction.  When you start to drive through the volleyball you not only fire your arm muscles, but you also concentrically contract your abdominals to further increase the speed of your arm.   Just like a catapult.  The same goes for a swimmer.  If you want to have a stronger stroke when you pull your arm through, start by training the eccentric contraction of your abdominal muscles to improve your arm power through the water.
 
 
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All swim strokes start with strong eccentric contractions throughout the core, hips, and shoulders

It is important to train your core muscles with eccentric abdominal work.  A few exercises that I love to do are reverse crunches, Russian twists (with or without a medicine ball), and overhead throws with a medicine ball.  These are pictured below.

The Reverse Crunch:

Russian Twists:

Overhead Med Ball Throws:

​Main points I hope you take away from this:
1) Your abs play a role in: how fast you throw a ball, how strong your swim stroke is, and how hard you spike.
2) The human body is one big kinetic chain, don’t neglect a part of it.
3) Having a 6 pack is not only for the beach but it is also for improving your athletic performance

​Reference:
Seroyer, S. T., Nho, S. J., Bach, B. R., Bush-Joseph, C. A., Nicholson, G. P., & Romeo, A. A. (2010). The kinetic chain in overhand pitching: its potential role for performance enhancement and injury prevention. Sports Health: A Multidisciplinary Approach, 2(2), 135-146.

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