{
  "$schema": "https://openexercise.org/schema/v0/exercise.json",
  "aliases": [
    {
      "text": "Leg Extension Isometric Hold",
      "kind": "common"
    },
    {
      "text": "Leg Extension Hold",
      "kind": "common"
    },
    {
      "text": "Isometric Quad Extension",
      "kind": "common"
    },
    {
      "text": "Leg Extension Isometric",
      "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"
      },
      {
        "muscle": "rectus-abdominis",
        "role": "stabilizer"
      }
    ],
    "joints": [
      {
        "joint": "knee",
        "actions": [
          "isometric-stabilization"
        ]
      },
      {
        "joint": "hip",
        "actions": [
          "isometric-stabilization"
        ]
      }
    ]
  },
  "classification": {
    "modalities": [
      "rehabilitation",
      "strength",
      "hypertrophy"
    ],
    "movement_patterns": [
      "isolation-knee-extension"
    ],
    "mechanics": "isolation",
    "force": "static",
    "kinetic_chain": "open",
    "laterality": "bilateral",
    "planes": [
      "sagittal"
    ],
    "contraction": [
      "isometric"
    ],
    "level": "beginner"
  },
  "equipment": {
    "required": [
      [
        "selectorized-machine",
        "plate-loaded-machine"
      ]
    ]
  },
  "external_ids": {
    "wger": "2535"
  },
  "id": "oec:isometric-leg-extension",
  "instructions": {
    "setup": [
      "Sit on the leg extension machine with your back firmly against the backrest.",
      "Align your knee joints with the machine's axis of rotation.",
      "Position the shin pad across the lower shins just above the ankles, and grip the side handles firmly."
    ],
    "steps": [
      "Extend your knees to the prescribed joint angle (commonly 45 to 60 degrees of flexion).",
      "Hold this fixed position under tension against the resistance for the targeted duration.",
      "Maintain steady quadriceps contraction without letting your hips lift or the weight drop.",
      "Carefully lower the weight back to the starting rest position under control once the hold is complete."
    ],
    "breathing": "Breathe continuously and evenly throughout the hold; avoid holding your breath.",
    "cues": [
      "Lock your hips down into the seat",
      "Squeeze your quads hard",
      "Stay motionless at the target angle"
    ],
    "common_faults": [
      {
        "fault": "Lifting the pelvis and lower back off the seat to leverage body weight.",
        "correction": "Grip the machine handles firmly to anchor your hips firmly into the cushion throughout the hold."
      },
      {
        "fault": "Holding breath and bearing down during the contraction.",
        "correction": "Maintain rhythmic, controlled diaphragmatic breathing for the duration of the set."
      },
      {
        "fault": "Allowing the leg position to drift downward as fatigue sets in.",
        "correction": "Hold a steady target joint angle; terminate the set when you can no longer maintain the required angle."
      }
    ],
    "safety": {
      "precautions": [
        "If using for patellar tendon rehabilitation, perform holds at mid-range angles (typically 45-60 degrees of knee flexion) rather than full terminal extension to reduce patellofemoral joint stress."
      ],
      "spotter": "not-needed"
    }
  },
  "measurement": {
    "duration_counted": "total",
    "load": {
      "convention": "weight-stack",
      "implements": 1,
      "kind": "external"
    },
    "profiles": [
      {
        "required": [
          "duration",
          "load"
        ],
        "optional": [
          "rpe"
        ]
      }
    ],
    "records": {},
    "reps_counted": "total"
  },
  "name": "Isometric Leg Extension",
  "previous_ids": [
    "oec:leg-extension-isometric"
  ],
  "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 Isometric",
        "url": "https://wger.de/en/exercise/2535/view-base",
        "license": "CC-BY-SA-4.0",
        "author": "HexoctusEngineering"
      }
    ]
  },
  "relations": [
    {
      "type": "variation-of",
      "target": "oec:leg-extension"
    },
    {
      "type": "substitute-for",
      "target": "oec:leg-extension"
    },
    {
      "type": "progression-of",
      "target": "oec:quad-set"
    }
  ],
  "setup": {
    "position": "seated",
    "range": "pause"
  },
  "status": "active",
  "summary": "An isometric isolation exercise where the quadriceps contract against fixed resistance without movement at the knee joint."
}