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Supine Knee to Elbow Crunches

This double-crunch pulls the knees toward the chest while the elbows curl to meet them over the midline, folding the body from both ends at once. Maddy programs it when a client is ready to combine the crunch and the reverse crunch into one movement. Coached by Maddy (NASM-CPT) — these are the exact form cues he gives on every client's first week.

Muscles worked

Abs · rectus abdominis Obliques

Sets & reps by goal

GoalSets × RepsRest
Strength3 × 5-6 slow reps with a 2-s top squeeze90 s
Muscle3 × 9-12 reps60 s
Endurance2-3 × 18-27 reps30-45 s

Rep ranges per Helms 2014 · Schoenfeld 2016.

Level — Beginner

Beginner-to-intermediate; the coordination of folding both ends at once is the real test, not raw strength.

Proper form — 5 cues

  1. Start with fingertips beside the temples and legs lifted, knees over hips.
  2. Fold from both ends — knees travel to meet the elbows over your middle.
  3. Peel the shoulder blades and the tailbone off the floor at the same time.
  4. Touch knees to elbows softly, then open back out with control.
  5. Stop opening the moment your lower back would leave the floor.

Breathing: Exhale hard as knees and elbows meet, inhale as the body opens back out.

The 3 mistakes Maddy corrects most

Pulling the head forward with the hands to close the gap.. The tug strains the neck and fakes range the abs never produced. Fix: Keep the fingertips resting lightly at the temples — if the elbows meet the knees, it must be the trunk that closed the distance.
Only the knees travelling while the torso stays flat.. That makes it a knee tuck — half the exercise — and the upper abs get a free ride. Fix: Check both contact points each rep: shoulder blades off the floor and tailbone curled up together.
Letting the legs drop away fast on the opening phase.. The uncontrolled lowering yanks the pelvis into a tilt and the lumbar arch takes the strain. Fix: Open the fold over two slow counts and shorten the leg travel until control returns.

Common questions

What's the difference between this and a regular crunch?

A regular crunch moves only the ribcage toward a fixed pelvis. Here the pelvis also curls toward the ribcage, so the abs shorten from both ends simultaneously — a longer contraction covering both the upper-biased and lower-biased patterns in a single rep. It is harder to do slowly than most people expect, which is exactly why it sits a step above the basic crunch in Maddy's progressions.

Can beginners do knee-to-elbow crunches?

Usually after two or three weeks of groundwork rather than day one. Own 15 clean regular crunches and 12 controlled knee tucks first, since this movement is those two stitched together. Starting with feet tapping down between reps instead of holding the legs up also reduces the demand while you learn the double-fold timing.

How many reps should I aim for?

Quality caps the number here. Start with 3 sets of 8 slow reps and add one rep per session while both contact points — shoulder blades and tailbone — still lift on every rep. Once you pass 12-15 with a genuine pause at the top, progress the exercise rather than the count: slow the opening phase, or move toward V-ups.

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