{
  "resourceType": "ActivityDefinition",
  "id": "eccentric-step-down",
  "url": "https://bodyiq.dev/fhir/ActivityDefinition/eccentric-step-down",
  "version": "1",
  "name": "EccentricStepDown",
  "title": "Eccentric Step-Down",
  "status": "draft",
  "experimental": true,
  "description": "Stand on a step on the working leg; slowly lower the non-working heel toward the floor, then return. Progress height 4\" → 8\" → 12\".",
  "useContext": [
    {
      "code": {
        "system": "http://terminology.hl7.org/CodeSystem/usage-context-type",
        "code": "user"
      },
      "valueCodeableConcept": {
        "text": "difficulty: intermediate"
      }
    }
  ],
  "topic": [
    {
      "coding": [
        {
          "system": "https://bodyiq.dev/fhir/CodeSystem/exercise",
          "code": "eccentric-step-down",
          "display": "Eccentric Step-Down"
        }
      ]
    }
  ],
  "bodySite": [
    {
      "coding": [
        {
          "system": "https://bodyiq.dev/fhir/CodeSystem/exercise",
          "code": "knee",
          "display": "Knee"
        },
        {
          "system": "http://snomed.info/sct",
          "code": "129159008",
          "display": "Structure of femorotibial joint"
        }
      ],
      "text": "Knee"
    },
    {
      "coding": [
        {
          "system": "https://bodyiq.dev/fhir/CodeSystem/exercise",
          "code": "hip",
          "display": "Hip"
        },
        {
          "system": "http://snomed.info/sct",
          "code": "24136001",
          "display": "Structure of hip joint"
        }
      ],
      "text": "Hip"
    }
  ],
  "kind": "ServiceRequest",
  "dosage": [
    {
      "text": "3×10, 2–3×/week. Progress step height."
    }
  ],
  "usage": "Evidence: strong. Produces highest hip flexion and adduction moment impulses among stepping tasks; effective for hip strengthening [Hatfield 2017].",
  "note": [
    {
      "text": "Tall trunk, level pelvis — quad and glute med control descent",
      "authorString": "focus:internal"
    },
    {
      "text": "Lower the trailing heel slowly to gently tap the floor",
      "authorString": "focus:external"
    },
    {
      "text": "Take three slow seconds on the way down",
      "authorString": "focus:external"
    },
    {
      "text": "Standing hip stays level — hand on hip checks",
      "authorString": "focus:tactile"
    }
  ],
  "extension": [
    {
      "url": "https://bodyiq.dev/fhir/StructureDefinition/muscle-involvement",
      "extension": [
        {
          "url": "muscle",
          "valueString": "Quadriceps Femoris"
        },
        {
          "url": "role",
          "valueCode": "primary"
        },
        {
          "url": "coding",
          "valueCoding": {
            "system": "http://snomed.info/sct",
            "code": "21989003"
          }
        }
      ]
    },
    {
      "url": "https://bodyiq.dev/fhir/StructureDefinition/muscle-involvement",
      "extension": [
        {
          "url": "muscle",
          "valueString": "Gluteus Medius"
        },
        {
          "url": "role",
          "valueCode": "primary"
        },
        {
          "url": "coding",
          "valueCoding": {
            "system": "http://snomed.info/sct",
            "code": "78333006"
          }
        }
      ]
    },
    {
      "url": "https://bodyiq.dev/fhir/StructureDefinition/muscle-involvement",
      "extension": [
        {
          "url": "muscle",
          "valueString": "Gluteus Maximus"
        },
        {
          "url": "role",
          "valueCode": "secondary"
        },
        {
          "url": "coding",
          "valueCoding": {
            "system": "http://snomed.info/sct",
            "code": "206007"
          }
        }
      ]
    },
    {
      "url": "https://bodyiq.dev/fhir/StructureDefinition/muscle-involvement",
      "extension": [
        {
          "url": "muscle",
          "valueString": "Hamstrings (Group)"
        },
        {
          "url": "role",
          "valueCode": "stabilizer"
        }
      ]
    },
    {
      "url": "https://bodyiq.dev/fhir/StructureDefinition/muscle-involvement",
      "extension": [
        {
          "url": "muscle",
          "valueString": "Soleus"
        },
        {
          "url": "role",
          "valueCode": "stabilizer"
        },
        {
          "url": "coding",
          "valueCoding": {
            "system": "http://snomed.info/sct",
            "code": "78376008"
          }
        }
      ]
    }
  ]
}