HOW TO DO CRUNCH
- Lie on your back, knees bent, feet on the floor. Hands on the chest or fingertips at the temples. Do not lace the fingers behind the head and yank.
- Tip the pelvis so the low back is quiet on the floor. Ribs down. That is the start. A gap under the lumbar is a sit-up waiting to happen.
- Exhale and curl the rib cage toward the pelvis. Shoulder blades leave the floor. Hips stay down. Eyes on the ceiling, not the knees.
- Lower the shoulders until the blades kiss the floor. Pause. The next rep starts there, not from a bounce.
- If the feet fly or the hip flexors take the set, shorten the curl. This is not a sit-up you cut in half.
COMMON MISTAKES
- Yanking the neck. Hands behind the head plus a pull is a neck set. Fingertips at the temples, elbows wide, chin slightly tucked. The ribs move. The head rides along.
- Peeling the lumbar off the floor. Once the low back leaves, you are on sit-up. Curl the ribs. If you keep coming up to seated, switch slugs instead of pretending the range is extra credit.
- Logging sit-ups or the crunch machine here. Floor bodyweight, sit-up, and machine-ab-crunch are three charts. Scan the floor slug for this. The pad with a stack is not this lift.
- Bouncing off the shoulder blades. A flop and a snap is momentum. Pause on the floor, then curl. If you need the bounce, you already used the reps that counted.
VARIATIONS
- Sit-up — Lumbar leaves the floor. Different slug, different hip-flexor tax.
- Machine ab crunch — Loaded pad. Scan that frame, not this floor slug.
- Reverse crunch — Pelvis toward ribs when the hip flexors steal the floor crunch.
- Kneeling cable crunch — Cable curl when you want load without turning it into a sit-up.
PROGRESSIONS
- Hands on the chest, slow curl, pause at the top, low back glued down.
- Fingertips at the temples once the neck stays quiet.
- Add a plate on the chest only after the curl is clean. Log the plate.
- Reverse crunch or the machine when you need load the floor cannot give.
PROGRAMMING NOTES
Isolation after the main lifts: 3 sets of 12–20. Log reps. If you hold a plate, log that weight. Floor crunch stays on this slug. Sit-up and machine-ab-crunch are different PRs. Pair with a plank or a hanging raise, not with another crunch variation in the same slot just to feel busy.
EQUIPMENT ALTERNATIVES
- Machine ab crunch — Use the stack when the floor is not enough load and the pad fits you.
- Kneeling cable crunch — Same rib-to-pelvis idea with a cable when there is no crunch machine.
- Plank — Brace instead of curl if flexion bothers the back today.
FREQUENTLY ASKED QUESTIONS
No. A sit-up peels the lumbar and uses the hip flexors to a seated position. A crunch is rib cage toward pelvis with the low back down. If you sat up, log sit-up. If you used the pad and the stack, log machine-ab-crunch.
