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Frog Crunch

A crunch performed with soles of the feet together and knees dropped wide, which slackens the hip flexors so the rectus abdominis does more of the work.

AbsBodyweightTrunk flexion
GoLightWeight mediafrog-crunch

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Primary

Rectus abdominis

Secondary

ObliquesHip flexors

Equipment

Bodyweight

Pattern

Trunk flexion

Setup

  1. 01Lie on your back and bring the soles of the feet together.
  2. 02Let the knees fall open toward the floor in a frog position.
  3. 03Place hands lightly behind the head or across the chest.
  4. 04Set the ribs down and press the lower back toward the mat.

Execution

  1. 01Exhale and curl the shoulders and upper back off the floor.
  2. 02Lift only as high as the abs can flex the spine, roughly 30 degrees.
  3. 03Pause briefly at the top with the abs fully shortened.
  4. 04Lower under control until the shoulder blades touch down.

Checkpoints

  • -Knees stay dropped wide the whole set; they do not squeeze together.
  • -The lower back stays in contact with the floor.
  • -Chin stays off the chest with a fist of space under the jaw.
  • -Each rep starts from a dead stop, not a bounce.

Common mistakes

  • -Pulling on the head with the hands.
  • -Turning the crunch into a full sit-up and letting hip flexors take over.
  • -Letting the knees drift up as fatigue sets in.
  • -Rushing reps and losing the top-position squeeze.

Programming notes

  • -Use 2 to 4 sets of 12 to 20 reps at the end of a session.
  • -Add a 1 to 2 second hold at the top before adding external load.
  • -Pairs well after a hip-flexor-dominant movement like hanging knee raises.

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