{
  "$schema": "https://openexercise.org/schema/v0/exercise.json",
  "aliases": [
    {
      "text": "Abdominal Crunch",
      "kind": "common"
    },
    {
      "text": "Floor Crunch",
      "kind": "common"
    },
    {
      "text": "Crunches",
      "kind": "common"
    }
  ],
  "anatomy": {
    "muscles": [
      {
        "muscle": "rectus-abdominis",
        "role": "prime-mover"
      },
      {
        "muscle": "external-oblique",
        "role": "synergist"
      },
      {
        "muscle": "internal-oblique",
        "role": "synergist"
      },
      {
        "muscle": "transversus-abdominis",
        "role": "stabilizer"
      },
      {
        "muscle": "deep-neck-flexors",
        "role": "stabilizer"
      }
    ],
    "joints": [
      {
        "joint": "thoracic-spine",
        "actions": [
          "flexion"
        ]
      },
      {
        "joint": "lumbar-spine",
        "actions": [
          "flexion"
        ]
      },
      {
        "joint": "cervical-spine",
        "actions": [
          "isometric-stabilization"
        ]
      }
    ]
  },
  "classification": {
    "modalities": [
      "calisthenics"
    ],
    "movement_patterns": [
      "spinal-flexion"
    ],
    "mechanics": "isolation",
    "force": "pull",
    "kinetic_chain": "open",
    "laterality": "bilateral",
    "planes": [
      "sagittal"
    ],
    "contraction": [
      "dynamic"
    ],
    "level": "beginner"
  },
  "equipment": {
    "optional": [
      "mat"
    ],
    "required": []
  },
  "external_ids": {
    "wger": "167,1933"
  },
  "id": "oec:crunch",
  "instructions": {
    "setup": [
      "Lie face up on the floor with your knees bent at about 90 degrees and your feet flat, hip-width apart.",
      "Place your fingertips lightly behind your ears or cross your arms over your chest, keeping your elbows flared wide.",
      "Flatten your lower back gently against the floor to engage your core."
    ],
    "steps": [
      "Exhale as you curl your ribcage down toward your pelvis, lifting your head and shoulder blades off the floor.",
      "Pause at the top of the contraction for a moment, squeezing your abdominals firmly while keeping your lower back anchored to the mat.",
      "Inhale as you slowly reverse the curl, lowering your shoulder blades back to the mat with control."
    ],
    "breathing": "Exhale forcefully during the upward crunch, and inhale smoothly as you lower your shoulders to the floor.",
    "cues": [
      "Pull your ribs toward your hips",
      "Keep your lower back glued to the mat",
      "Imagine holding an apple between your chin and chest"
    ],
    "common_faults": [
      {
        "fault": "Pulling on the head and neck with the hands, causing excessive cervical flexion.",
        "correction": "Keep fingertips light against your temples or cross your arms over your chest; focus on moving your torso, not your head."
      },
      {
        "fault": "Lifting the lower back off the ground into a full sit-up, engaging the hip flexors excessively.",
        "correction": "Shorten the range of motion; only lift the shoulder blades while keeping the lower back flat on the floor."
      },
      {
        "fault": "Using momentum to bounce off the floor between repetitions.",
        "correction": "Slow the tempo down and pause briefly at both the top contraction and bottom reset."
      }
    ],
    "safety": {
      "precautions": [
        "Avoid forcefully tucking the chin to the chest; keep the cervical spine neutral."
      ],
      "spotter": "not-needed"
    }
  },
  "measurement": {
    "load": {
      "convention": "not-applicable",
      "kind": "bodyweight"
    },
    "profiles": [
      {
        "required": [
          "reps"
        ],
        "optional": [
          "duration",
          "rpe"
        ]
      }
    ],
    "records": {},
    "reps_counted": "total"
  },
  "name": "Crunch",
  "previous_ids": [
    "oec:crunches",
    "oec:abdominal-crunch"
  ],
  "provenance": {
    "generated": [
      "/name",
      "/summary",
      "/classification",
      "/anatomy",
      "/equipment",
      "/measurement",
      "/instructions",
      "/setup",
      "/relations"
    ],
    "license": "CC-BY-SA-4.0",
    "review": {
      "status": "machine-generated",
      "model": "gemini-3.8-flash",
      "at": "2026-10-31"
    },
    "sources": [
      {
        "title": "wger: Crunches",
        "url": "https://wger.de/en/exercise/167/view-base",
        "license": "CC-BY-SA-3.0",
        "author": "wger.de"
      },
      {
        "title": "wger: Abdominal Crunch",
        "url": "https://wger.de/en/exercise/1933/view-base",
        "license": "CC-BY-SA-4.0",
        "author": "amaesc"
      }
    ]
  },
  "relations": [
    {
      "type": "regression-of",
      "target": "oec:sit-up"
    },
    {
      "type": "substitute-for",
      "target": "oec:sit-up"
    },
    {
      "type": "regression-of",
      "target": "oec:decline-crunch"
    },
    {
      "type": "regression-of",
      "target": "oec:weighted-crunch"
    },
    {
      "type": "substitute-for",
      "target": "oec:machine-crunch"
    },
    {
      "type": "substitute-for",
      "target": "oec:cable-kneeling-crunch"
    }
  ],
  "setup": {
    "position": "supine",
    "range": "full",
    "stance": {
      "kind": "parallel",
      "width": "hip"
    }
  },
  "status": "active",
  "summary": "A foundational bodyweight abdominal exercise performed lying supine that targets the rectus abdominis through spinal flexion."
}