{
  "resourceType": "ActivityDefinition",
  "id": "nordic-hamstring-exercise",
  "url": "https://bodyiq.dev/fhir/ActivityDefinition/nordic-hamstring-exercise",
  "version": "1",
  "name": "NordicHamstringExercise",
  "title": "Nordic Hamstring Exercise",
  "status": "draft",
  "experimental": true,
  "description": "Kneeling with ankles anchored, eccentrically lowering body forward using hamstring control. Produces highest hamstring activation among eccentric exercises (BF 64.5% MVIC). Eccentric training reduces hamstring injury by 56.8-70%. Increases BF long head fascicle length (MD 0.90 cm), a key adaptation for injury prevention. Semitendinosus preferentially recruited over biceps femoris.",
  "useContext": [
    {
      "code": {
        "system": "http://terminology.hl7.org/CodeSystem/usage-context-type",
        "code": "user"
      },
      "valueCodeableConcept": {
        "text": "difficulty: advanced"
      }
    }
  ],
  "topic": [
    {
      "coding": [
        {
          "system": "https://bodyiq.dev/fhir/CodeSystem/exercise",
          "code": "nordic-hamstring-exercise",
          "display": "Nordic Hamstring Exercise"
        }
      ]
    }
  ],
  "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"
    }
  ],
  "kind": "ServiceRequest",
  "dosage": [
    {
      "text": "Progressive: start 1×5, build to 3×12 over 10 weeks. 1-2 sessions/week. Part of FIFA 11+ programs [Rudisill 2023, Ripley 2023]"
    }
  ],
  "usage": "Evidence: strong. BF 64.5% MVIC, ST > BF > SM activation. Distal BF long head shows higher activation than proximal [Li 2023]. Fascicle length increase MD 0.90 cm [Rudisill 2023]",
  "note": [
    {
      "text": "Long line from knees to crown — hamstrings hold the body",
      "authorString": "focus:internal"
    },
    {
      "text": "Lower the chest toward the floor as slowly as possible",
      "authorString": "focus:external"
    },
    {
      "text": "Push the floor away with the hands to return",
      "authorString": "focus:external"
    },
    {
      "text": "Body falls like a controlled drawbridge",
      "authorString": "focus:imagery"
    }
  ],
  "relatedArtifact": [
    {
      "type": "citation",
      "label": "kisner-therapeutic-2017",
      "citation": "Kisner C, Colby LA, Borstad J. (2017). Therapeutic Exercise: Foundations and Techniques"
    },
    {
      "type": "citation",
      "label": "acsm-guidelines-2021",
      "citation": "American College of Sports Medicine. (2021). ACSM's Guidelines for Exercise Testing and Prescription",
      "document": {
        "url": "https://doi.org/10.4135/9781412994149.n165"
      }
    }
  ],
  "extension": [
    {
      "url": "https://bodyiq.dev/fhir/StructureDefinition/muscle-involvement",
      "extension": [
        {
          "url": "muscle",
          "valueString": "Hamstrings (Group)"
        },
        {
          "url": "role",
          "valueCode": "primary"
        }
      ]
    },
    {
      "url": "https://bodyiq.dev/fhir/StructureDefinition/muscle-involvement",
      "extension": [
        {
          "url": "muscle",
          "valueString": "Gluteus Maximus"
        },
        {
          "url": "role",
          "valueCode": "stabilizer"
        },
        {
          "url": "coding",
          "valueCoding": {
            "system": "http://snomed.info/sct",
            "code": "206007"
          }
        }
      ]
    },
    {
      "url": "https://bodyiq.dev/fhir/StructureDefinition/muscle-involvement",
      "extension": [
        {
          "url": "muscle",
          "valueString": "Transversus Abdominis"
        },
        {
          "url": "role",
          "valueCode": "stabilizer"
        },
        {
          "url": "coding",
          "valueCoding": {
            "system": "http://snomed.info/sct",
            "code": "86493009"
          }
        }
      ]
    }
  ]
}