Side Plank Dumbbell Rear Delt Fly

In SetGrip: Dumbbell Rear Delt Fly (Side Plank)

Secondary muscles
Delts, Abs
Body part
Back
Position
Lying
Laterality
Unilateral (one side at a time)
Category
Strength

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Holding a side plank while the top arm performs a rear delt fly makes the obliques and shoulder share every rep, because the fly's arc actively tries to tip the plank over. Choose the dumbbell by what the plank can tolerate rather than what your rear delt can lift, which usually means the lightest pair on the rack.

How to do the Side Plank Dumbbell Rear Delt Fly

  1. Start by lying on your side with your legs extended and stacked on top of each other.
  2. Place your forearm on the ground directly below your shoulder, keeping your elbow bent at a 90-degree angle.
  3. Hold a dumbbell in your top hand, with your arm extended straight down towards the ground.
  4. Engage your core and lift your hips off the ground, creating a straight line from your head to your heels.
  5. While maintaining the side plank position, lift the dumbbell up towards the ceiling, squeezing your shoulder blades together.
  6. Lower the dumbbell back down to the starting position.
  7. Repeat for the desired number of repetitions, then switch sides.

Tip: Imagine hugging a barrel rather than pushing a weight.

Muscles worked

Primary

Upper Back · Back

On reverse flies the rhomboids and mid traps squeeze the shoulder blades together at the end of each rep.

Secondary

  • Delts — Rear delt flies work the back of the shoulder as the arms swing wide, and the front delt assists on any chest fly.
  • Abs

Common mistakes

  • Elbows bending as you tire — this turns a fly into a press; set the elbow angle at the start and keep it constant for the whole set.
  • Going too heavy — flies are a stretch and squeeze movement, not a strength lift; you should be able to pause at the bottom without the shoulders rolling forward.
  • Stopping short of the stretch — let the arms open until you feel the chest or rear delts lengthen, then bring them back under control.
  • Not squeezing at the finish — the last few inches are where the muscle shortens most, so hold the contraction for a count before opening again.

Where it fits in a workout

Flies are an isolation movement for after the pressing or rowing is done. Pair a chest fly with a rear delt fly for a balanced superset.

How many sets, how heavy and how hard: see what the ACSM position stands support.

Variations and alternatives

Similar exercises

When to talk to someone

  • Chest discomfort, feeling faint or lightheaded, or trouble breathing during or after exercise can be signs of a heart attack. In the US, call 911 right away; elsewhere, call your local emergency number.
  • Heart, metabolic or kidney disease, or symptoms like these when you are active: talk to your doctor before you start or step up training.
  • Pregnant: ask your obstetric care provider which exercise suits you.

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More exercises

Sources

  1. ACSM position stand on exercise quantity and quality (Garber et al., 2011)
  2. ACSM preparticipation health screening (Riebe et al., 2015)
  3. ACOG Committee Opinion No. 804 on exercise in pregnancy (2020)
  4. CDC: About Heart Attack Symptoms, Risk, and Recovery (2024)

Sources checked on October 17, 2026. Full citations are in the exercise library.

Animation and exercise data: ExerciseDB, licensed to SetGrip. General information, not medical or coaching advice.