{
  "$schema": "https://openexercise.org/schema/v0/exercise.json",
  "aliases": [
    {
      "text": "quad extension",
      "kind": "common"
    },
    {
      "text": "seated leg extension",
      "kind": "common"
    },
    {
      "text": "machine leg extension",
      "kind": "common"
    }
  ],
  "anatomy": {
    "muscles": [
      {
        "muscle": "rectus-femoris",
        "role": "prime-mover"
      },
      {
        "muscle": "vastus-lateralis",
        "role": "prime-mover"
      },
      {
        "muscle": "vastus-medialis",
        "role": "prime-mover"
      },
      {
        "muscle": "vastus-intermedius",
        "role": "prime-mover"
      }
    ],
    "joints": [
      {
        "joint": "knee",
        "actions": [
          "extension",
          "flexion"
        ]
      }
    ]
  },
  "classification": {
    "modalities": [
      "hypertrophy",
      "strength"
    ],
    "movement_patterns": [
      "isolation-knee-extension"
    ],
    "mechanics": "isolation",
    "force": "push",
    "kinetic_chain": "open",
    "laterality": "bilateral",
    "planes": [
      "sagittal"
    ],
    "contraction": [
      "dynamic"
    ],
    "level": "beginner"
  },
  "equipment": {
    "required": [
      [
        "selectorized-machine",
        "plate-loaded-machine"
      ]
    ]
  },
  "external_ids": {
    "wger": "369"
  },
  "id": "oec:leg-extension",
  "instructions": {
    "setup": [
      "Adjust the backrest so the axis of rotation of the machine aligns directly with your knee joints.",
      "Position the lower leg pad so it rests comfortably against your lower shins just above the ankles.",
      "Sit back firmly against the pad, grasp the side handles, and pull yourself down into the seat."
    ],
    "steps": [
      "Extend your knees smoothly to raise the pad until your legs are fully straightened.",
      "Pause briefly at peak contraction without hyperextending or lifting your hips from the seat.",
      "Lower the weight under control back to the starting flexed position."
    ],
    "breathing": "Exhale as you extend your legs and inhale as you lower the weight.",
    "cues": [
      "Keep your hips glued to the seat",
      "Squeeze your quads at the top",
      "Control the descent"
    ],
    "common_faults": [
      {
        "fault": "Kicking or using momentum to swing the weight up.",
        "correction": "Initiate the movement smoothly and maintain a controlled cadence throughout."
      },
      {
        "fault": "Hips lifting off the bench during the repetition.",
        "correction": "Pull up firmly on the machine handles to lock your pelvis into the seat."
      },
      {
        "fault": "Misaligned knee pivot point with the machine axis.",
        "correction": "Adjust the seat back so your knees line up directly with the machine's pivot point."
      }
    ],
    "safety": {
      "precautions": [
        "Avoid aggressive hyperextension at the top of the movement, especially under heavy loads."
      ],
      "spotter": "not-needed"
    }
  },
  "measurement": {
    "load": {
      "convention": "weight-stack",
      "implements": 1,
      "kind": "external"
    },
    "profiles": [
      {
        "required": [
          "reps",
          "load"
        ],
        "optional": [
          "rpe"
        ]
      }
    ],
    "records": {
      "e1rm": true,
      "volume": true
    },
    "reps_counted": "total"
  },
  "name": "Leg Extension",
  "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: Leg Extension",
        "url": "https://wger.de/en/exercise/369/view-base",
        "license": "CC0-1.0",
        "author": "BFad07"
      }
    ]
  },
  "relations": [
    {
      "type": "regression-of",
      "target": "oec:single-leg-leg-extension"
    },
    {
      "type": "progression-of",
      "target": "oec:isometric-leg-extension"
    },
    {
      "type": "substitute-for",
      "target": "oec:reverse-nordic-curl"
    }
  ],
  "setup": {
    "position": "seated"
  },
  "status": "active",
  "summary": "An open-chain machine exercise that isolates the quadriceps through seated knee extension."
}