Why Shoulder Stability Matters for Throwers: Building a Stronger, More Resilient Arm

By Dr. Carmen Jansante, PT, DPT, CSCS

Undefeated Physical Therapy and Performance

When people hear the word “stability,” they often think about simply keeping a joint from moving. While that is partially true, stability is much more than just being “still.” Especially in overhead athletes and throwers, stability means being able to control a joint dynamically while moving through high-speed ranges of motion.

At  Undefeated Physical Therapy and Performance, we work with a large number of baseball and softball athletes, so shoulder stability is something we discuss daily. The throwing shoulder experiences tremendous forces during the throwing motion, and if the body cannot stabilize efficiently, athletes often develop pain, tightness, decreased velocity, or feelings of instability.

What Is Shoulder Stability?

Stability is the body’s ability to maintain control of a joint and keep it centered during movement. In the shoulder specifically, this becomes extremely important because the shoulder sacrifices stability for mobility. The glenohumeral joint is designed to move through massive ranges of motion, but that also means the body must work harder to keep the joint controlled.

Dynamic stability means the shoulder can move through motion while maintaining proper positioning and control. This is especially critical in throwing athletes, where the arm rapidly accelerates and decelerates under high stress.

The shoulder relies on both static and dynamic stabilizers.

Static Stabilizers

Static stabilizers are anatomical structures that help provide passive support to the shoulder joint. These include:

• The labrum

• Joint capsule

• Ligaments

• Glenoid structure

The labrum plays a major role by creating a suction effect that helps keep the humeral head centered in the glenoid. This passive stability is essential for maintaining shoulder integrity during movement.

Dynamic Stabilizers

Dynamic stabilizers are the muscles surrounding the shoulder that actively create control and stability during movement. These are the structures we can train and improve through rehabilitation and strength training.

Major dynamic stabilizers include:

• Rotator cuff muscles

  • Subscapularis

  • Teres minor

  • Supraspinatus

  • Infraspinatus

• Deltoid

• Pectoral musculature

• Serratus anterior

• Latissimus dorsi

These muscles work together to maintain joint centration and help the shoulder tolerate the demands of throwing, lifting, pressing, and athletic movement.

Common Signs of Shoulder Instability

When people think of instability, they often imagine the feeling that a joint is “going to pop out.” While that can absolutely happen, instability presents itself in many other ways that are much more subtle.

Some common complaints include:

• “My shoulder feels loose.”

• “I don’t trust my arm in certain positions.”

• “My arm feels weak late in games.”

• “I feel like I can’t keep my shoulder in place.”

• “My shoulder is always tight no matter how much I stretch.”

That last statement is one of the most common things we hear in overhead athletes.

“My Shoulder Always Feels Tight”

Many athletes constantly stretch their shoulders because they feel tight, but the root problem is often not mobility — it is stability.

If the shoulder lacks dynamic stability, the surrounding muscles attempt to compensate by increasing tension and guarding. Essentially, the body tightens the area in an attempt to create protection and control.

In many cases, the athlete does not actually need more stretching. They need improved muscular coordination, control, and stability.

This is especially common in throwers who spend repetitive time in extreme ranges of motion.

Shoulder Stability Drills We Commonly Use

There are hundreds of excellent shoulder stability exercises available, but here are a few of our favorites that we frequently incorporate into rehabilitation and arm care programs.

1. Screwdriver Drill

This is one of my favorite early-stage dynamic stability drills.

The athlete lies flat on their back holding a light dumbbell with the arm extended toward the ceiling. We can keep the feet flat on the floor or elevate them to increase core involvement. Sometimes we also add a serratus punch to increase serratus anterior activation.

From there, the athlete slowly rotates through internal and external rotation while attempting to keep the arm stable and controlled.

The goal is not heavy loading. The goal is control.

We typically perform:

• 15–20 controlled rotations

• Light resistance

• Slow tempo

• Focus on maintaining shoulder position

I do not force full internal rotation because excessive internal rotation under load can create impingement symptoms. Instead, we work through comfortable ranges while emphasizing control.

To progress the exercise, we may:

• Perform it in a side plank position

• Use a water-filled stability implement such as a water bag

• Add perturbations or unstable loading challenges

The moving water creates constant changes in force, forcing the shoulder stabilizers to react dynamically.

2. Switch Foot Jump Waiter Hold

This is a great drill for integrating lower-body movement with upper-body stability.

The athlete holds a dumbbell or unstable load in a “waiter position”:

• Shoulder at approximately 90 degrees

• Elbow bent at 90 degrees

• Arm held stable in front of the body

The athlete then performs repeated split-stance jumps while switching foot positions.

The goal is not maximal jumping height. The focus is maintaining shoulder position while the body moves dynamically underneath it.

We commonly use:

• 15–20 second intervals

• Controlled rhythmic jumps

• Light to moderate loading

This drill challenges the shoulder to stabilize against forces generated from the lower body and trunk.

3. Rhythmic Stabilization

Rhythmic stabilization is a staple in both rehabilitation and performance training.

A common setup might involve a banded row-to-rotation-to-press movement. After several repetitions, I’ll have the athlete pause and hold the final position.

From there, I apply manual perturbations in different directions while cueing:

“Don’t let me move you.”

The athlete’s job is to react and maintain joint position without losing control.

This creates rapid neuromuscular activation and teaches the shoulder to respond dynamically to unpredictable force.

4. Hanging Band Press Variations

Another stability drill we frequently use involves hanging kettlebells or weight plates from resistance bands during pressing movements.

The unstable load creates oscillation and movement throughout the exercise. At the top of the press, gravity and the swinging load challenge the shoulder stabilizers significantly.

We often coach:

• Smooth, controlled pressing

• Slightly faster concentric movement

• Pause and stabilize at the top

This variation heavily challenges the anterior shoulder musculature, pecs, and rotator cuff while improving shoulder control under instability.

Final Thoughts

Shoulder stability is essential for both rehabilitation and performance. In throwers especially, stability is not about making the shoulder “stiff.” It is about creating controlled mobility and dynamic strength through extreme ranges of motion.

Sometimes the answer is not more stretching.

Sometimes the body is asking for better control.

At  Undefeated Physical Therapy and Performance, we love helping athletes build stronger, healthier, and more resilient shoulders through individualized arm care and performance programs.

If you are dealing with shoulder pain, tightness, instability, or looking to improve your throwing performance, we would love to help.

Call or text: (412) 627-2131 

Instagram:  @undefeated_pt

References

1. Kibler WB, Sciascia A. Current concepts: scapular dyskinesis. British Journal of Sports Medicine. 2010.

2. Reinold MM, Escamilla RF, Wilk KE. Current concepts in the scientific and clinical rationale behind exercises for glenohumeral and scapulothoracic musculature. Journal of Orthopaedic & Sports Physical Therapy. 2009.

3. Wilk KE, Arrigo CA, Andrews JR. Current concepts: the stabilizing structures of the glenohumeral joint. Journal of Orthopaedic & Sports Physical Therapy.

4. Cools AM, Johansson FR, Cambier D, et al. Descriptive profile of scapulothoracic position, strength and flexibility variables in adolescent elite tennis players. British Journal of Sports Medicine.

Myers JB, Laudner KG, Pasquale MR, et al. Scapular position and orientation in throwing athletes. American Journal of Sports Medicine.