Hip-Shoulder Separation: Is It Really The X-Factor To Increasing Velocity?

Hip-Shoulder Separation: Is It Really The X-Factor To Increasing Velocity?

Allow me to introduce to you, one of the brightest people I've met in my 20+ years of baseball, Dr. Emily Ferree. I met "Dr. Emily" last year when I was interviewing biomechanists to help test The Core Velocity Belt. What enticed me most was she had a way of making the complex simple. Her understanding of biomechanics and human movement is second to none. 

By the way, Dr. Emily Ferree is my favorite follow on Twitter.  I highly recommend you follow her!  I'll let Dr. Emily take it from here.

We’ve all heard it - the X factor - it’s what separates the elites from the novice rotational athlete.

  • It’s the drool-worthy slow motion video you see on the PGA tour where the pelvis starts that famous rotation BEFORE the torso begins (insert shock and awe - fainting women from the sheer beauty of it all).
  • You’ve probably seen the kinematic sequencing graph with the three different colored peaks, each growing taller than the next, pelvis, torso, arm…. Ah the beauty.

When you first learn something about analyzing the movement of a rotational athlete we learn about hip to shoulder separation which is the process by which the pelvis initiates rotation, separating the pelvis from the trunk. This “X factor” as it’s been nicknamed, is thought to be the key to developing power and transferring energy from the ground up.

Well, what if I told you the way most people view hip to shoulder separation may be very wrong.  In fact, it could be the reason so many pitchers, even the most athletic, with all the potential in the world get worse when introduced to coaching and pitching mechanics.  

The high value placed on Hip to shoulder separation is a prime example as to how research gets misused in baseball.

Here's where the baseball research went wrong:

  1. Mass data and the law of averages applied to the individual
  2. Correlative assumptions analyzed in retrospect
  3. Mistake What v. Why variables
  4. Still frame data applied to continuous movement

Here’s what hip to shoulder separation actually does:

  • As pitchers stride down the mound and unwind from their top position the front leg strides into abduction and the pelvis initiates rotation.
  • The pelvis reaches its top rotational velocity before the torso reaches its top rotational velocity.
  • Finally followed by the arm reaching its top rotational velocity. (I'd probably also add, more importantly, elbow extension velocity - but this is another topic for a separate conversation).

This moment of separation as the pelvis rotates towards home plate and dissociates from the torso creates a stretch reflex embedded deep in our fascial and neuromuscular system which helps the pitcher coordinate muscles across a reciprocal movement pattern. 

This allows the athlete to kinetically link, the lower and upper body.

  1. In short, it creates a functional whip from the lower to the upper body.
  2. It helps with efficiency, power production, muscle coordination, and connection.

However, when researchers and biomechanists first started analyzing pitching mechanics (most notably Tom House) the sequencing of rotational velocity stood out as a key variable that separated the elite from the amateur and quickly fell into the fallacy of “if a little is good, a lot is better”.

Now if hip to shoulder separation is so valuable, why am I taking issue?

My problem is in the application.

Because hip/shoulder separation has become such a focus for so many pitchers, it's created it's share fair of side effects.  

  1. Over-rotation
  2. Pushing arm actions
  3. Disconnected upper and lower bodies
  4. Flying open way too early.
  5. Ever noticed how so many who teach hip/shoulder separation constantly remind their pitchers to "stay closed"?  

Most of the young guys I see with movement faults:

  1. Fly open way too early.
  2. Struggle to control rotation
  3. Arms act independently of their feet. 
  4. Low-level motor coordination

Why do so many pitchers experience other problems when being trained to increase hip/shoulder separation? 

Here’s why:

  • Most people’s perception of hip to shoulder separation is the hip initiates rotation while the torso is completely still.
  • What many people train is the pelvis movement separated and disconnected from the torso and in isolation from the hips.
  • What we train often is one segment moving independently of the other.

The power of hip to shoulder separation comes when everything is moving together.

We create a separation (FOR A BRIEF MOMENT IN TIME) then ballistically begin to close the gap and bring everything back together, which is the real key to hip/shoulder separation. 

So if you create SO much separation that it takes longer to close the gap your rate of force development plummets as does your power production and most likely a drop in velocity. 


  • Because of the effort to fix what’s wrong, pitchers' compensate by trying to generate more power from the arm itself. 
  • Which drastically increases a pitcher's risk for injury.

 I cannot tell you how many times I’ve seen this play out.

Recently, Driveline came out with research correlating pelvis position at stride foot contact with elbow torque and risk for injury.

  1. The result of their study was that guys who landed more open had decreased elbow stress.
  2. Now you put a headline like that out on the interwebs and the grand takeaway is - I need to get my pitcher to rotate his hips more.
  3. And all I want to say is WAIT A MINUTE AND THINK CRITICALLY.

The number they correlated with decreased elbow stress is 60 degrees open, with 90 degrees being fully opened to home-plate.

  • This means the pelvis is not fully opened and is still opening towards home AFTER stride foot contact.
  • Meaning at stride foot contact when the torso is gaining momentum the pelvis is still rotating WITH the torso.

If we take one range of motion measured at a split second in time and make this the outcome goal with the perception that more pelvic rotation is good - chances are the true outcome will be...

  • We either coach our kids to open way too much, or...
  • Input a cognitive perception into their CNS to stride as open as possible.

 The problem with the fallacy of “if a little is good, a lot is better” with hip to shoulder separation is that …

  1. We ask many pitchers to move through and control a range they don’t have.
  2. And too much separation defies muscle physiology.

All muscles follow an optimal length-tension relationship, which means there is a relationship between the length of a muscle and the amount of force or tension that muscle can create. In extremely short and extremely long muscular positions, our ability to create force drastically drops off.

The graph below details the relationship between muscle length and force development.

So if we max out hip to shoulder separation

  1. We create a length across specifically the core musculature
  2. Which makes it nearly impossible to create enough force and tension to transfer power up the chain to the arm
  3. Which often leads to soft tissue injury. 

Look at these two pitchers above.

  1. One has WAY more separation at SFC (stride foot contact) and almost a completely open pelvis.
  2. The other still has room to open and looks way more connected.

Judge for yourself, who looks more powerful, more stable, more ready to rotate ballistically?

In my opinion, hip to shoulder separation is not an input variable, it's an output variable.

  1. We don’t train output variables.
  2. We train input variables that result in output variables.

Here's the problem I see with "baseball science".

We studied pitching, realized elite pitchers separated hips and shoulders then tried to make everyone do that without understanding why the elites did it or how the elites did it.

  1. Hip to shoulder separation is a RESULT  of proper motor control, muscle activation patterns.
  2. And ultimately the pitcher's ability to STOP rotation and control their body through the middle.

The discussion on the importance of deceleration for optimal mechanics is long and so important so I’ll just leave that there for now. All I will say on this topic, for now, is that...

When two objects are in motion and you want to transfer momentum from one to the other:

  • The less kinetic energy (movement) one object maintains
  • The more kinetic energy (movement and velocity) the other is given 

(The transfer of energy up the kinetic chain requires one segment to slow down and transfer energy for the other to accelerate.). 

  1. A pitcher has to have the ability to initiate movement at the hips which comes from proper anchoring and posture of the back hip.
  2. Pelvic rotation is largely controlled, accelerated, and decelerated by our glute muscles.

But without going into a long diatribe about how we do this etc, I would say that if you want optimal hip to shoulder separation you need to start by

  1. Teaching a pitcher to control their hips,
  2. Train them to control their posture as they lift the lead leg. 
  3. Give them a sensory awareness of their center.  (Core Velocity Belt)
  4. Put pitchers in a position for success where they can actually control rotation and stop rotation, and just see what happens. 

Instead of just pushing guys to separate more, let’s teach them control from the middle, the ability to coordinate rotation TOGETHER.

Allow them to operate in ranges where they are powerful, not overstretched, and weak. (I’ll add, there are other input variables that affect healthy rotational sequencing other than stride length, this is just an example). 

Here’s an example of a MiLB pitcher I evaluated for Eugene Bleecker at 108 Performance.

  1. This pitcher had posterior impingement and shoulder pain and was told he needed more hip to shoulder separation.
  2. When he focused on separating MORE he developed the above-mentioned shoulder pain and his velocity took a steep drop.

Look at the picture on the top. People were telling him to separate more because they saw a torso that was opening too early.

So the faulty thought is...

If the torso opens early, there isn’t enough dissociation between the hips and the torso, so the hips are pulling the torso.  Traditional thought is to work on opening and stretching the hips and if he has more range of motion, the torso can hold off. FALSE.

The truth is...

  • His torso is opening too early because his hips have run out of room and are yanking his torso with them.
  • Look how open his pelvis is, he was nowhere else to go.
  • He has exhausted his range of motion.

At this point in his delivery his pelvis and torso are almost done with their path, they have very little range of motion left to go through but his arm still has a long way to go.  Which means - the majority of what’s about to happen after SFC ALL has to come from his arm - ouch people. 

This second picture is what happened when Eugene shortened his stride and had him externally rotate his back foot.  And bam -

  1. His pelvis is more closed at contact and he still has separation. 
  2. He's now able to hold off his torso and once both feet are planted in the ground and...
  3. He still has room to rotate with power

At this point in time his pelvis and torso still have the ability to carry the arm through, keeping his upper and lower half connected and vastly decreasing the amount of stress on the arm.

And if you were wondering, his shoulder pain went away.

Be sure to follow Dr. Emily Ferree on twitter!


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