Pitching Biomechanics: Hip Shoulder Separation, Closing the Gap

hip and shoulder

We have talked in the past about hip-shoulder separation and its importance in the pitching motion. In this article, we will dive deeper into the idea of “closing the gap” after max separation has occurred. More specifically:

    • When does it occur (timing)
    • How quickly does it close (explosiveness)
    • How completely does it close

We will also review some potential issues and how we may address them.

Hip Shoulder Separation

As a review, hip-shoulder separation is the angle a pitcher creates by separating their hips and their torso through rotation.

hip shoulder separation

This movement acts like a rubber band being pulled back in a slingshot, storing energy in the trunk as the separation is increased and the rubber band is stretched further. This energy will then be released and used to accelerate the torso open towards the hips creating a whip affect much like letting the band go and continuing the transfer of energy up the kinetic chain to the arm. This slingshot effect of the torso accelerating towards the hips going into release is what we refer to as “closing the gap”.

Most times the inability to efficiently close the gap is more a result of inefficient timing / sequencing (usually poor hip deceleration) rather than any physical or mobility limitations. By efficiently closing the gap, we allow for proper anatomical positioning and sequencing, while maximizing energy transfer and efficiency up the chain.

This is also referred to as “timing” and puts a pitcher in a better position to increase their throwing velocity while minimizing their risk of injury. This concept of timing is much more vital to the throw than simply trying to create as much separation as possible.

By increasing how fast we stretch the rubber band (oblique abdominals) during hip-shoulder separation while decreasing the time between that stretch and first contraction, we close the gap more rapidly, thus creating more power in the movement and eventually the throw.

hip shoulder separation

pitching biomechanics

This athlete achieves peak hip-shoulder separation (67°) and max stretch right before foot plant (blue vertical line) and is then able to close the gap with a hip-shoulder separation angle of 4° at release (red vertical line). He is able to do this through proper acceleration of the torso and deceleration of the pelvis.

So, what we’re basically saying is the amount of hip-shoulder separation is only part of the equation, as much relies on an individual’s ability to close the gap quickly and efficiently.  In a sport like baseball where rate of force development / time constraints is key, quickly is the key word here.

When We Say Closed, We Mean Closed

Most elite ball players (hitters included) can have anywhere from 30 degrees to upwards of 55 degrees of hip-shoulder separation. How much separation is optimal differs from athlete to athlete based largely on the length of the torso and the amount of slack that needs to be pulled out. But one metric that is fairly constant in these athletes is that they all eventually close the gap at release (or contact for a hitter) with the torso and hips being within 0- 5 degrees of each other.

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Some Possible Causes and Potential Solutions

Poor Pelvis Deceleration – Being able to efficiently decelerate the hip at foot plant will help create an efficient lead leg block and transfer of energy up the kinetic chain. This allows the athlete to create torso rotation passively and in turn reduces voluntary muscle engagement i.e., “muscling” the pitch.

Many pitchers that have trouble closing the gap have problems with this passive movement, and think they need to aggressively pull their front shoulder through in order to rotate as fast as possible instead of letting their torso rotation naturally unfold. This can create a “stiff” upper half and bypass oblique activation. This can also lead to being overly rotational, decreasing efficiency and leaving energy on the table. Creating strength in the glutes and hamstrings and training co-contraction of the front hip helps to create the braking forces needed to adequately decelerate. These two exercises really help get the job done.


(Med Ball Pulse w/ Stick)

Pelvis Deceleration / Torso Deceleration Timing – A pitcher’s ability to close the gap not only relies on how fast they can decelerate, but also when they begin to decelerate. To close the gap effectively and efficiently, a pitcher must decelerate his pelvis immediately after foot plant, while the torso is still accelerating. This gives the torso time to speed up and gain ground on the pelvis which is slowing down. If a pitcher decelerates their pelvis late or decelerates their torso early, this will cause what we refer to as a “gate” motion where the pelvis and torso are decelerating at the same time and thus rotating together. If the pelvis and torso are both rotating together, then the torso never has a chance to catch up to the pelvis.  This can result in a large amount of hip-shoulder separation at release (NOT closing the gap) and putting the body in a poor position to transfer force to the ball.

Step behind throws is one way to help work on timing of the hips and torso together by getting the lower half going earlier if that’s what is needed, while letting the athlete feel separation by keeping the upper half closed a bit longer (note: be careful though, simply cueing an earlier hip rotation can force the back leg to shut down proper glute activation and negatively affect transfer of force from the core).

(Step Behind Throws)

Poor Core Strength and Stability – All movement is generated and originates from the center (core) making the spine and the surrounding tissue and fascia key players for closing the gap. But as the hips begin to rotate one way and the shoulders another, we create tension (torque) and ultimately stability. This requires a strong core to be able to hold that stability and the ability to then assist unwinding forcefully. Thus, closing the gap.

Infielder throws are a great drill to let the athlete start feeling generation of force from the middle by completing a throw while taking away the natural anchor point of the ground. This also helps to create fascial tension across the anterior and posterior oblique chains while helping him disassociate his arm from the rest of his body to help break apart the gate motion we touched on earlier. We use reverse infielder throws as a regression or to start guys off feeling the engagement of the core.

(Reverse Fielder Throws)

(Fielder Throws)


The two graphs below are the hip-shoulder separation angle during a pitch (left) and then a snippet of the same pitcher’s kinematic sequence (right), which is a graph of angular velocities of the pelvis (red), torso (green), shoulder (purple), and hand (yellow).  Examples are from two different pitchers one who is unable to close the gap and one who is able to close the gap.

Inability to Close the Gap – The pitcher with the inability to close the gap has a max hip-shoulder separation of 57° before foot plant (vertical blue line), and still has 40° of separation at release (vertical red line). The inability to close the gap for this athlete is due to early torso deceleration causing a “gate” motion as seen by the pelvis (red) and torso (green) curves following the same decline and since the torso and the pelvis are rotating together the torso is never able to catch up to the pelvis.

Inability to Close the Gap

pitching biomechanics

Closing the Gap – The second pitcher below does both a better job of timing his hip-shoulder separation (we want it at or after foot plant) and closing the gap. This pitcher has 54° of max hip-shoulder separation, and then 0° at release due to the fact that his pelvis begins decelerating as his torso is still accelerating allowing time for the torso to catch up to the pelvis.

Closing the Gap

pitching biomechanics


In summary, all movement is originated from the center/core, making the spine and the surrounding tissue and fascia key players for closing the gap. While this may involve improvements in strength and/or mobility in many younger athletes, we have found that poor hip shoulder separation is more a result of an inefficient timing and sequence (usually poor hip deceleration), rather than any physical or mobility limitations when dealing with elite level athletes who already possess a great amount of strength and mobility.

The quicker we can efficiently close the gap, the harder and more efficiently we can throw or hit the baseball.

See ya’ in the gym…

By Nunzio Signore (BA, CSCS, CPT, NASM, FMS) and Courtney Semkewyc (RPP Bio-mechanist Intern, PhD Candidate Biomedical Engineering)

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