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Machine Ab Crunch — abs isolation exercise in the LIFTAG library

Machine Ab Crunch

Isolation · Weight × reps

Adjust the seat, chest or shoulder pad, and foot supports so the machine’s axis and starting position feel natural. Brace, exhale, and curl the rib cage toward the pelvis through spinal flexion while keeping the hips relatively still. Pause in the shortened position, then return slowly without allowing the stack to pull the torso backward. The machine crunch trains the rectus abdominis and obliques against adjustable resistance; depending on the design, hip flexors may also contribute. Keep the neck aligned rather than leading with the chin, use a controlled range instead of maximal rounding, and reduce the load if the movement shifts into the hips or lower back.

IN THE APP

iOS and AndroidGet LIFTAG free

Scan the machine's QR tag and this exercise opens ready to log: sets, rest timer, PRs, and your whole progression for Machine Ab Crunch.

FOUND ON THESE MACHINES

HOW TO DO MACHINE AB CRUNCH

  1. Set the seat, chest or shoulder pad, and foot supports so the machine’s axis sits around the mid-ribs, not on the hips.
  2. Brace, grab the handles or take the pad, and start tall. This is a curl, not a sit-up you bought a stack for.
  3. Exhale and curl the rib cage toward the pelvis. The hips stay relatively quiet; the spine flexes.
  4. Return until you are tall again without the stack slamming. Stretch is fine; a bounce is not a rep.

COMMON MISTAKES

  • Hip-flexor yanking the pad down. If you feel it mostly in the front of the hips, you are folding at the hip, not curling the trunk. Shorten the range and slow the eccentric.
  • Seat so high you shrug the pad. The machine should load the abs, not the traps. Drop the seat until the pad sits on the chest or shoulders and the axis matches the ribs.
  • Logging this as a floor crunch. Loaded machine vs bodyweight floor is a different chart. Scan the tag on this frame so LIFTAG opens machine-ab-crunch.
  • Bouncing the stack off the top pins. The curl is the work. If you need the bounce, drop a plate and pause at the bottom of the curl.

VARIATIONS

  • Crunch — Floor version, no stack, same rib-to-pelvis idea.
  • Kneeling cable crunch — Cable line of pull when the machine is taken or the pad does not fit you.
  • Hanging leg raise — Hanging flexion if you want legs moving instead of a pad.
  • Reverse crunch — Pelvis toward ribs when the hip flexors dominate the machine.

PROGRESSIONS

  1. Light pin, two-second curl, two-second return.
  2. Add load when the hips stay quiet for all reps.
  3. Pause in the contracted position before you chase a heavier stack.
  4. Move to kneeling cable crunches if the machine’s axis never matches your torso.

PROGRAMMING NOTES

Isolation after the main lifts: 3 sets of 10–15. It is not a deadlift. At a partner gym the QR or NFC tag on this frame should open this slug — if it opens crunch or sit-up, tell the gym so the log stays honest. Pair with a hanging raise or a Pallof press, not with another crunch machine.

FREQUENTLY ASKED QUESTIONS

Open Machine Ab Crunch in LIFTAG, or tap the NFC tag / scan the QR code on the machine at a partner gym. Log each working set as weight × reps. The rest timer starts after you save the set, and PRs plus estimated 1RM update automatically.

MORE ABS EXERCISES

CrunchCrunchKneeling Cable CrunchKneeling Cable CrunchHanging Leg RaiseHanging Leg RaiseRussian TwistRussian TwistKneeling Ab RolloutKneeling Ab RolloutPlankPlankSit-UpSit-UpBicycle CrunchBicycle Crunch