Alternating Forearm Supported Knee Raise

Beginner Isolation 15% of bodyweight

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A core exercise done half-reclined on your forearms, raising one bent knee toward your chest at a time while the other foot stays on the floor. Trains the abs to hold your torso still while the legs alternate.

Also known as: propped knee raise, elbow supported knee raise, reclined alternating knee raise

How to do the Alternating Forearm Supported Knee Raise

  1. Lean back on your forearms, elbows under your shoulders.
  2. Bend your knees, feet flat on the floor.
  3. Raise one bent knee until the thigh is nearly vertical.
  4. Lower that foot as the other knee rises.
Full technique — 6 steps
  1. Sit on the floor and lean back onto your forearms, elbows under your shoulders and palms down.
  2. Bend your knees and place both feet flat on the floor in front of you.
  3. Tighten your stomach and pull your shoulders down away from your ears.
  4. Lift one foot and raise that bent knee toward your chest until the thigh is nearly vertical.
  5. Lower that foot to the floor as you raise the other knee the same way.
  6. Keep alternating legs at a steady pace without rocking your upper body.

Common mistakes

  • Rocking the torso to lift the leg
  • Swinging knees for momentum
  • Shrugging shoulders toward ears
  • Letting the lower back arch
  • Dropping the foot hard between reps

Form cues

  • Lift from the abs
  • Keep shoulders down
  • Keep torso quiet
  • Keep knees bent

Substitutes by equipment

Same muscles, same movement — pick the version you have the gear for.

Barbell

Resistance bands

Weight plates

Suspension trainer

Where to start and where to go next

Same muscles, same movement. Too hard for now — step down; once it gets easy — step up.

  1. Easier Seated Ab Machine Beginner
  2. This exercise Alternating Forearm Supported Knee Raise 15% of bodyweight
  3. Harder Reverse Crunch 25% of bodyweight
  4. Harder Ab Wheel Pass Crunch 30% of bodyweight

Too hard for now? Start with the Seated Ab Machine.

Quick answers

What muscles does the Alternating Forearm Supported Knee Raise work?

Primary: Abs 8/10. Also works: Obliques 4/10, Lower back 3/10.

When should I do the Alternating Forearm Supported Knee Raise in a workout?

Finisher. Goes last, once the heavy work is done. ≈ 5 min with rest.

How many sets and reps of the Alternating Forearm Supported Knee Raise?

Strength: 3 sets of 8–12 reps, rest 1 min, 3 reps in reserve. Muscle growth: 3–4 sets of 12–20 reps, rest 45 s, 3 reps in reserve. Endurance: 2–3 sets of 20–30 reps, rest 30 s, 3–4 reps in reserve.

What can I do instead of the Alternating Forearm Supported Knee Raise?

Barbell: Barbell Overhead Sit-Up. Resistance bands: Resistance Band Dead Bug, Lying Resistance Band Crunch. Weight plates: Plate Overhead Sit-Up. Suspension trainer: Suspension Trainer Mountain Climbers, Supine Suspension Trainer Knee Tuck.

What is an easier version of the Alternating Forearm Supported Knee Raise?

Seated Ab Machine (Beginner).

What is a harder version of the Alternating Forearm Supported Knee Raise?

Reverse Crunch (25% of bodyweight), Ab Wheel Pass Crunch (30% of bodyweight).

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