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Crunches

The crunch is the most fundamental ab isolation there is: shoulder blades curling off the floor, ribs folding toward the pelvis, and back down — nothing else moving. Done strictly, it remains one of the most effective direct rectus abdominis exercises ever measured; done sloppily, it is a neck workout. 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 × 3–6 (5 s reps or weighted)90 s
Muscle3 × 9–1260 s
Endurance2–3 × 18–2745 s

Rep ranges per Helms 2014 · Schoenfeld 2016.

Level — Beginner

The first ab exercise most people should learn — and one worth doing strictly forever.

Proper form — 5 cues

  1. Lie with knees bent, feet flat and hip-width on the floor.
  2. Rest fingertips behind your ears — never laced behind the head.
  3. Curl the ribs toward the pelvis until the shoulder blades leave the floor.
  4. Pause and squeeze at the top for one second.
  5. Lower with control until the blades — not the head — return to the floor.

Breathing: Exhale fully as you curl up — the empty lungs deepen the contraction — inhale lowering.

The 3 mistakes Maddy corrects most

Yanking the head forward with the hands. The neck provides the visible movement while the abs contribute a fraction of their capacity. Fix: Keep a fist of space under your chin and let the fingertips rest weightlessly.
Sitting all the way up. Past the shoulder blades' lift-off, the hip flexors take over — more range, less ab. Fix: Stop at roughly 30 degrees of curl; the rep is smaller than pride wants it to be.
Flopping down between reps. The released tension at the bottom turns one set of twenty into twenty sets of one. Fix: Touch the blades down lightly and rebound into the next curl without resting.

Common questions

Do crunches give you abs?

They build the abdominal muscle — thicker, stronger, more defined once it is visible. Whether it becomes visible is decided by body-fat level, which crunches barely influence because the movement burns very few calories. The honest formula: crunches (and other core work) for the muscle, a sustained calorie deficit for the reveal. Neither substitutes for the other.

How many crunches a day should I do?

Daily hundreds are a tradition, not a plan. Treat the abs like any muscle: two to four focused sessions weekly, a few sets of 10–20 strict reps taken close to failure, progressed over time with pauses, tempo, or load. Fifty quality reps a week beats five hundred neck-pulls, and your spine will thank you for the difference.

Are crunches bad for your back?

For healthy spines at sensible volumes, current evidence does not support the scare stories — the load in a strict bodyweight crunch is modest. Problems come from enormous daily volumes, yanked necks, and pre-existing conditions. If you have a back issue, get personal guidance; if not, strict crunches in normal doses are a reasonable tool.

Related exercises

Harder: Butterfly Crunches

Alternate Leg Raises (Modified)Abs · Hip flexors Cable Seated in and OutAbs · Hip flexors Chair CrunchesAbs Cross Mountain ClimbersAbs · Hip flexors Cross Mountain Climbers (Modified)Abs · Hip flexors

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