Why Your Shoulders Take Over Chest Flyes (And How to Fix It)

Chest flyes don’t usually fail because of effort or focus. They fail because the chest isn’t set up properly.

When someone tells me they feel flyes mostly in the front of their shoulders, I don’t assume they’re doing anything wrong mentally. I assume their chest and shoulders aren’t in a position where the chest can do the work.

This is something I see every week during personal training sessions in Chiswick.

A client lies back for dumbbell flyes. The first few reps look fine. Then, as fatigue builds, the shoulders creep upward, the chest drops toward the bench, and the movement quietly shifts away from the pecs. The weights still move — but the work has changed.

That’s not a concentration issue. It’s a setup issue.

What Goes Wrong When the Chest Loses Its Setup

The body will always move a load using whatever muscles are in the best position to help.

If the chest collapses and the shoulders drift forward, the pecs lose their ability to produce force. From there, a few predictable things happen:

• The ribcage drops toward the bench

• The upper arm rolls slightly forward in the socket

• Load shifts away from the chest and into the shoulders

At that point, the fly becomes a long-lever shoulder exercise. That’s why it often feels unstable, uncomfortable, or “pinched” at the joint — especially toward the end of a set.

This isn’t just inefficient training. Over time, it’s one of the most common reasons people develop irritated shoulders during flyes and pressing movements.

When I see shoulders rising toward the ears, I see a leak in the movement. Tension has left the chest and gone somewhere it shouldn’t.

The Fix: Set the Chest Before You Move the Weight

You don’t need more weight. You don’t need more intensity.

You need a better setup.

Mid-set, I’ll usually make two simple adjustments.

First: “Show me the logo on your shirt / Lift the chest up” This encourages gentle thoracic extension. The ribcage opens, and the chest is placed on a slight, productive stretch — without forcing an exaggerated arch.

Second: “Put your shoulder blades in your back pockets.”This brings the shoulders down and settles them against the bench, instead of letting them drift upward as the set goes on.

Once those two things are in place, the dumbbells stay in line with the mid-chest rather than drifting toward the face.

The difference is usually immediate. The shoulders stop dominating. The chest takes over. Most people feel it within the same set.

Why This Matters More Than People Think

The bench isn’t passive equipment. It supports your entire upper-body position.

If the chest and shoulders aren’t set properly before the first rep, the body will compensate — especially as fatigue builds. This is why chest flyes often feel fine at the start and then “turn into” a shoulder exercise halfway through.

Effective training isn’t about forcing reps through poor positions. It’s about putting the body in a position where the right muscles can actually do their job.

When the chest is set and the shoulders are settled, flyes become what they’re meant to be: controlled, joint-friendly, and effective.

Chest Fly Diagnostic: If You Feel X, Check Y

This is how I coach flyes in real time. Use it mid-set or between sets. You only need to fix one thing at a time.

If you feel it mostly in the front of your shoulders

→ Check your chest position

• Has your chest collapsed toward the bench?

• Can you lift your chest slightly without forcing an arch?

If the chest isn’t lifted, the shoulders will take over.

If your shoulders creep toward your ears

→ Check your shoulder blades

• Are they drifting upward as the set goes on?

• Can you keep them gently pulled down rather than pinched hard together?

Think down and settled, not squeezed.

If the set feels strong at first but unstable by rep 5 or 6

→ Check your setup before the first rep

• Were your shoulders anchored before you lifted the dumbbells?

• Did you rush the setup just to get the weights moving?

Most fly problems start before the set even begins.

If you feel a pinch or strain in the shoulder joint

→ Check your arm path

• Are the dumbbells drifting toward your face instead of staying over mid-chest?

• Are your elbows bending and straightening during the rep?

Keep the arc consistent and the elbows softly fixed.

If you feel it more in your arms than your chest

→ Check elbow position and intent

• Are your elbows staying slightly bent throughout the movement?

• Are you thinking “bring the arms together” rather than “move the hands”?

Flyes are about bringing the upper arms together — not the dumbbells.

If everything feels loose or disconnected

→ Check your lower body

• Are your feet planted and gently driving into the floor?

• Is your ribcage staying still, or collapsing and flaring each rep?

A quiet lower body makes the upper body work better.

One Coaching Note That Solves Most Issues

Most chest fly problems don’t need a full reset. They need one correction, applied early.

In live sessions, I usually fix chest position first, then shoulder position, then arm path — in that order. Once those are set, the chest almost always does what it’s supposed to do.

Final Thought

If chest flyes consistently feel like a shoulder exercise, it’s rarely a strength issue.

It’s almost always a setup issue.

Fix how you’re lying on the bench before you worry about how much weight you’re lifting.

And if you’re training in Chiswick and want a second set of eyes on your technique, that’s exactly how I coach sessions — calmly, deliberately, and with long-term joint health in mind.