The Subscapularis: The Missing Link for Velocity in Baseball Players

By Dr. Carmen Jansante, PT, DPT, CSCS Undefeated Physical Therapy & Performance Pittsburgh, Pa

When it comes to arm care in baseball, most athletes—and even many programs—focus heavily on the back side of the shoulder. External rotation work, band exercises, and scapular stability drills dominate the conversation.

But there’s one muscle that often gets overlooked… and it might be the key to both velocity and shoulder health:

The subscapularis muscle.

What Is the Subscapularis?

The subscapularis is one of the four rotator cuff muscles, but it’s different from the other three.

It’s the only rotator cuff muscle that sits on the front side of the shoulder blade, attaching to the front of the humerus. Because of its position, it plays a unique and critical role in shoulder function.

It has two primary responsibilities:

• Internal rotation of the shoulder

• Stabilization of the front (anterior) shoulder

For throwers, both of these are essential.

This muscle is not just another rotator cuff muscle—it is a powerful internal rotator and a major contributor to arm speed.

The Subscapularis in the Throwing Motion

The subscapularis is active throughout the entire throwing motion, acting as both a brake and an engine.

Late Cocking Phase

As the arm moves into full external rotation (layback position), the subscapularis works eccentrically.

Its job here is to:

• Control excessive external rotation

• Prevent the humerus from translating too far forward

Think of it as a brake system, protecting the front of the shoulder.

Acceleration Phase

This is where the subscapularis really shines.

It contracts concentrically (shortening) to drive internal rotation—this is the motion that contributes heavily to arm speed and velocity.

If you’re looking for where velocity comes from, this muscle is a big piece of the equation.

Deceleration / Follow-Through

The subscapularis continues working to provide dynamic stability as forces transfer through the arm after ball release.

What Happens When the Subscapularis Isn’t Functioning Well?

Weakness or Poor Activation

If the subscapularis isn’t doing its job:

• The front of the shoulder becomes unstable

• Increased stress is placed on:

  • The labrum

  • The biceps tendon

This is something we commonly see in athletes who overemphasize external rotation strength but neglect internal rotation work.

Tightness and Loss of Range of Motion

This is where things get really important.

The subscapularis is constantly active in throwers. Over time, because it is repeatedly contracting and shortening, it can become adaptively tight.

This isn’t just “tightness” in the traditional sense—it’s the muscle trying to:

• Protect the front of the shoulder

• Provide stability

But when it becomes too restricted, it can:

• Limit external rotation (layback)

• Decrease velocity potential

• Alter mechanics

If you feel like you can’t “get back” into full layback, or your velocity is dropping, your subscapularis could be a major contributor.

Why Stretching Alone Isn’t the Answer

A tight subscapularis doesn’t just need to be stretched.

It needs:

1. Release of the tissue

2. Strengthening through full range of motion

Without both, the problem often comes right back.

How We Treat the Subscapularis at Undefeated PT & Performance

The subscapularis sits on the front side of the shoulder blade, making it a difficult muscle to access.

At Undefeated Physical Therapy & Performance, we use hands-on techniques to directly target it.

Manual Therapy Approach:

• Athlete lies on their back

• Shoulder is positioned into protraction to lift the shoulder blade

• We access the muscle by working under the armpit, through the lat

  
  

From there, we use:

• Sustained pressure (trigger point release)

• Strumming techniques (cross-friction)

• Mobilization with movement (our most effective method)

This involves applying pressure to the muscle while moving the arm through:

• Internal rotation

• External rotation

• Shoulder flexion

This combination helps restore both mobility and function.

Strengthening the Subscapularis

Once mobility is restored, strengthening is key.

Common exercises include:

• Internal rotation at the side

• Internal rotation at 90°

• Isometric internal rotation holds

• Gravity-resisted internal rotation lifts

A more advanced variation we like:

• Driving the elbow into a surface while performing internal rotation

  • This reduces anterior deltoid dominance

  • Helps isolate the subscapularis more effectively

Final Thoughts

The subscapularis is one of the most important muscles for throwing athletes—but it’s also one of the most overlooked.

If it’s:

• Weak → you lose stability

• Tight → you lose range and velocity

Optimizing this muscle can be a game changer for both performance and injury prevention.

Need Help?

If you feel like:

• You’re lacking layback

• Your velocity has dropped

• Your shoulder just doesn’t feel right

Your subscapularis could be the missing piece.

We’d love to help.

📲 Message us on Instagram: @undefeated_pt 

📞 Call or Text: 412-627-2131

References

• Kibler WB, Sciascia A. Current concepts: scapular dyskinesis. Br J Sports Med.

• Reinold MM, Wilk KE, Fleisig GS, et al. Electromyographic analysis of the rotator cuff and deltoid musculature during common shoulder exercises. J Orthop Sports Phys Ther.

• Fleisig GS, Barrentine SW, Escamilla RF, Andrews JR. Biomechanics of overhand throwing. J Orthop Sports Phys Ther.

• Wilk KE, Arrigo CA. Current concepts in the rehabilitation of the overhead throwing athlete. Am J Sports