The Forearm Muscle Group You’re Probably Not Training Enough

Why Baseball Players Need More Than Wrist Curls for Arm Strength and Elbow Health

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

When most athletes think about forearm training, they probably think about one thing: wrist curls.

Flexion. Extension. Up and down.

You’ve probably seen it before—someone sitting on a bench with a dumbbell in their hand, forearm supported, repeatedly flexing and extending the wrist.

There’s nothing wrong with training wrist flexion and extension. These are important movements and should have a place in a complete strength program.

But for baseball players, pitchers, overhead athletes, and anyone who relies heavily on their elbow and forearm, there’s another component that is often overlooked:

Pronation and supination.

And if you aren’t training these movements, you may be leaving an important piece of your forearm and elbow-strength program on the table.

Your Forearm Does More Than Move Your Wrist

Your forearm is responsible for much more than simply bending your wrist up and down.

It also controls rotation of the forearm.

Pronation

Pronation is the motion of turning your palm downward.

Think about turning your palm toward the floor.

Supination

Supination is the opposite—turning your palm upward toward the ceiling or sky.

These movements are produced by multiple muscles working together, including the pronator teres, pronator quadratus, supinator, and biceps brachii.

For baseball players, these muscles play an important role because throwing is not simply a shoulder movement. It is a coordinated movement involving the entire kinetic chain—from the legs and trunk all the way through the shoulder, elbow, forearm, wrist, and hand.

The forearm is part of that chain.

So why are we spending so much time training flexion and extension while often ignoring rotation?

The Flexor-Pronator Connection to the Elbow

This is where things become particularly important for throwing athletes.

The muscles on the medial side of the forearm—commonly referred to as the flexor-pronator mass—contribute to dynamic stability of the medial elbow.

The pronator teres, flexor carpi ulnaris, flexor digitorum superficialis, and other muscles in this region work together to help resist valgus forces placed on the elbow. Anatomical and biomechanical research has demonstrated that these muscles can assist the medial elbow structures during valgus loading. (PubMed⁠)

Why does that matter for baseball?

Because pitching creates significant valgus stress at the elbow.

The ulnar collateral ligament (UCL) is an important passive stabilizer of the medial elbow, but it doesn’t work alone. The surrounding muscles also contribute to elbow stability.

One study examining baseball pitchers found significant activation of the pronator teres during pitching, with greater peak activation during curveball pitching compared with fastball pitching. (PubMed⁠)

More recent research has also examined the relationship between forearm flexor-pronator muscle activity and medial elbow gapping during repetitive maximal-effort pitching, further highlighting the importance of the forearm musculature in managing the stresses associated with throwing. (PubMed Central (PMC)⁠)

Important distinction:

Training your forearm does not guarantee that you will avoid a UCL injury.

Baseball elbow injuries are multifactorial. Workload, throwing volume, velocity, mechanics, recovery, previous injury, strength, mobility, and numerous other factors all matter.

But if the forearm muscles contribute to dynamic elbow stability, it makes sense that they should be trained—not ignored.

Don’t Forget About Grip Strength

There’s another reason forearm training matters for baseball players:

Grip strength changes with fatigue.

A recent study examining high-level amateur pitchers during a simulated 75-pitch game found that dominant-arm grip strength decreased by approximately 12.7%, while forearm soreness increased as the pitch count progressed. Pitching velocity also decreased slightly. (PubMed⁠)

Research examining professional baseball pitchers has similarly demonstrated that grip strength can decline over the course of a game. In one study, average grip strength decreased from approximately 124.5 pounds before the game to 113.1 pounds after the fourth inning. (PubMed⁠)

This doesn’t mean that every decrease in grip strength causes an injury.

It does, however, demonstrate something important:

The forearm is working—and it gets tired.

If you’re asking your forearm to repeatedly grip and control a baseball at high velocities, it makes sense to develop its strength and capacity.

Baseball Players Don’t Just Need Strong Forearms. They Need Well-Trained Forearms.

This is where I think many training programs miss the bigger picture.

You can have strong wrist flexors.

You can have strong wrist extensors.

You can have a strong grip.

And still neglect forearm rotation.

Baseball players repeatedly move through pronation and supination during throwing, hitting, fielding, and training.

The goal shouldn’t necessarily be to make one direction dramatically stronger than the other.

Instead, we want to develop the capacity to produce and control force through multiple directions of movement.

That is especially important when you’re dealing with an athlete who has a history of elbow pain, UCL injury, throwing-related forearm pain, or a return-to-throw program.

What About Supination?

Supination deserves attention, too.

The supinator muscle is one of the primary muscles responsible for forearm supination, while the biceps brachii is also a powerful contributor to this movement.

This is one reason the biceps is important beyond simply bending your elbow.

The biceps also helps rotate the forearm.

A good example is a distal biceps rupture.

Someone with a distal biceps tear may still be able to bend their elbow because other muscles can contribute to elbow flexion. But they can experience a significant loss of supination strength, particularly when trying to rotate the palm upward against resistance.

This is also where the term “Popeye deformity” can come into play after certain biceps ruptures—the muscle can retract and create a visible bulge in the upper arm.

The takeaway?

Supination is a legitimate strength movement—not just a motion you accidentally get during curls.

How We Train Pronation & Supination

There are plenty of ways to train these movements.

You don’t need expensive equipment to get started.

1. Resistance Band Pronation & Supination

A simple resistance band can be attached to a stable object and used to train forearm rotation.

This is an easy option for athletes at virtually any training level.

2. Dumbbell or Lever-Based Training

Holding a dumbbell or lever and rotating the forearm can create resistance through pronation and supination.

This can be more challenging because the farther the resistance is from the hand, the greater the torque.

3. Barbell Variations

A barbell can also be used for forearm rotation, although it isn’t always as smooth or convenient as other options.

4. Dedicated Forearm Rotation Devices

One tool we’ve recently incorporated into our training at Undefeated Physical Therapy & Performance is the Sport Grip device.

One of the things I like about it is the ability to adjust resistance while specifically targeting forearm rotation.

For baseball players, I particularly like performing the movement with the elbow extended in front of the body.

Why?

Because we can put the forearm in a position that more closely resembles the arm position athletes experience toward the end of a throwing motion while limiting the ability to compensate through the rest of the body.

One simple option is:

20 pronation repetitions → 20 supination repetitions

Adjust the resistance based on the athlete and their training level.

The goal isn’t to completely destroy your forearms every workout.

The goal is to progressively build strength, endurance, and control.

Want to Try the Sport Grip?

We’ve been using the Sport Grip in our training and rehabilitation programs to help athletes specifically target forearm rotation.

SPORT GRIP DISCOUNT LINK / CODE HERE

Undefeated Physical Therapy & Performance may receive consideration for recommending this product. Athletes should choose equipment based on their individual needs and training goals.

And remember—you don’t need this device to train pronation and supination.

Bands, dumbbells, barbells, and other simple tools can all be effective.

The important part is actually training the movement.

What This Means for Baseball Players

For pitchers, the forearm is an important part of the throwing system.

For hitters, grip and forearm strength contribute to controlling the bat.

For catchers and infielders, the ability to rapidly transition the hand and forearm through different positions is part of throwing and receiving.

And for athletes returning from elbow or forearm injuries, rebuilding strength and capacity throughout the entire forearm can be an important part of a progressive rehabilitation program.

At Undefeated Physical Therapy & Performance, we don’t look at the elbow in isolation.

We look at the athlete.

That means evaluating the shoulder, elbow, forearm, wrist, grip, trunk, lower body, throwing mechanics, workload, and overall strength and conditioning.

Because baseball injuries rarely come down to one muscle or one exercise.

Stop Training Only Up and Down

Wrist flexion and extension are important.

But the forearm was designed to do more than move up and down.

It rotates. It grips. It stabilizes. It transfers force.

For baseball players—especially pitchers—those functions matter.

If your arm-care program consists entirely of bands around the shoulder and wrist curls, it may be time to look at the bigger picture.

Add pronation.

Add supination.

Train grip strength.

Build forearm capacity.

And make sure your program actually prepares your arm for the demands you’re asking it to handle on the baseball field.

Need Help With Baseball Rehab or Arm Care in Pittsburgh?

At Undefeated Physical Therapy & Performance, we work with baseball players and athletes throughout the Pittsburgh area on injury rehabilitation, return-to-throw programs, strength and conditioning, arm care, and performance training.

If you’re dealing with elbow pain, forearm pain, a UCL injury, or you’re trying to safely return to throwing after an injury, don’t wait until the problem gets worse.

Follow us on Instagram: @undefeated_pt

Email: carmen@undefeatedpt.com

Call/Text: 412-627-2131

References & Further Reading

1. Tamura A, Saito M. Muscle Activity Characteristics of the Pronator Teres during Throwing in Baseball Pitchers: A Pilot Study. Healthcare. 2023. PubMed – Pronator Teres Activity During Baseball Pitching⁠

2. Lin F, et al. Muscle contribution to elbow joint valgus stability. Journal of Shoulder and Elbow Surgery. PubMed – Muscle Contribution to Elbow Valgus Stability⁠

3. The proximal origins of the flexor-pronator muscles and their role in the dynamic stabilization of the elbow joint. PubMed – Flexor-Pronator Anatomy & Elbow Stability⁠

4. Tremblay M, et al. Grip strength, muscle soreness and pain threshold perception evolution in baseball pitchers in a simulated 75-pitch game. BMJ Open Sport & Exercise Medicine. BMJ Open Sport & Exercise Medicine⁠

5. Change in Grip and Pinch Strength Over the Course of a Game in Professional Baseball Pitchers. PubMed – Grip Strength Changes in Professional Pitchers⁠

6. Effect of grip strength and grip strengthening exercises on instantaneous bat velocity of collegiate baseball players. PubMed – Grip Strength and Bat Velocity⁠