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One-Arm Flat Bench Dumbbell Flye

Performed unilaterally with one arm to expose left/right asymmetries, this variation primarily targets your Chest. It requires dumbbell and is best suited to beginner lifters.

Beginner level · Equipment: Dumbbell · Isolation · Push

Primary muscles: Chest

How to perform One-Arm Flat Bench Dumbbell Flye

  1. Step 1. Lie down on a flat bench with a dumbbell in one hand resting on top of your thigh. The palm of your hand with the dumbbell in it should be at a neutral grip.
  2. Step 2. By using your thighs to help you get the dumbbell up, clean the dumbbell so that you can hold it in front of you with your lifting arm being fully extended. Remember to maintain a neutral grip with this exercise. Your non lifting hand should be to the side holding the flat bench for better support. This will be your starting position.
  3. Step 3. Your arm with the weight should have a slight bend on your elbow in order to prevent stress at the biceps tendon. Begin by lowering your arm with the weight in it out in a wide arc until you feel a stretch on your chest. Breathe in as you perform this portion of the movement. Tip: Keep in mind that throughout the movement, your lifting arm should remain stationary; the movement should only occur at the shoulder joint.
  4. Step 4. Return your lifting arm back to the starting position as you squeeze your chest muscles and breathe out. Tip: Make sure to use the same arc of motion used to lower the weights.
  5. Step 5. Hold for a second at the contracted position and repeat the movement for the prescribed amount of repetitions.
  6. Step 6. Switch arms and repeat the exercise.

Frequently asked questions

What are the primary muscles targeted by the one-arm dumbbell flye?

The movement primarily isolates the pectoralis major. The single-arm variation increases core engagement as the obliques and stabilizers work to prevent the torso from rotating off the bench.

How do I maintain proper form and stability during this unilateral exercise?

Keep your feet planted firmly on the ground and your free hand on your hip or the edge of the bench. Focus on a controlled arc, keeping a slight bend in the elbow to protect the joint.

What is a common mistake to avoid when performing one-arm flyes?

Avoid letting the weight pull your shoulder into excessive horizontal abduction, which can strain the connective tissue. Do not allow your hips or shoulders to tilt toward the weighted side.

How should a beginner progress into this movement?

Start with a light weight to master the balance requirements of unilateral loading. If stability is too difficult, perform standard bilateral dumbbell flyes before moving to the one-arm version.

What are the recommended sets and reps for this exercise?

Perform 2 to 3 sets of 10 to 15 repetitions per side. Use this as a finishing movement later in your chest workout rather than a primary heavy lift.

Sample sets & reps for One-Arm Flat Bench Dumbbell Flye

  • Form first: 3 sets × 10-12 reps, 60s rest. RPE 6, focus on the target muscle.
  • Hypertrophy: 3 sets × 12-15 reps, 45-60s rest. RPE 7-8, controlled eccentric.
  • Burnout finisher: 2 sets × 15-20 reps, 45s rest. RPE 9, last set to failure.

Pick the scheme that matches your goal. Beginners should start at the lower end of every range; progress weight only when you hit the upper end of the rep range with one or two reps in reserve.

Related Chest exercises

  • Alternating Floor Press — kettlebell
  • Barbell Bench Press - Medium Grip — barbell
  • Barbell Guillotine Bench Press — barbell
  • Barbell Incline Bench Press - Medium Grip — barbell
  • Behind Head Chest Stretch — stretch

See all Chest exercises →

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