{
  "resourceType": "ActivityDefinition",
  "id": "wall-sit",
  "url": "https://bodyiq.dev/fhir/ActivityDefinition/wall-sit",
  "version": "1",
  "name": "WallSit",
  "title": "Wall Sit",
  "status": "draft",
  "experimental": true,
  "description": "Stand with your back flat against a wall, feet hip-width apart and about 1.5-2 foot-lengths away from the wall. Slide down until your hips and knees are bent to roughly 90 degrees with shins vertical, and hold the position isometrically while breathing normally. Slide back up the wall to finish the set.",
  "useContext": [
    {
      "code": {
        "system": "http://terminology.hl7.org/CodeSystem/usage-context-type",
        "code": "user"
      },
      "valueCodeableConcept": {
        "text": "difficulty: beginner"
      }
    }
  ],
  "topic": [
    {
      "coding": [
        {
          "system": "https://bodyiq.dev/fhir/CodeSystem/exercise",
          "code": "wall-sit",
          "display": "Wall Sit"
        }
      ]
    }
  ],
  "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": "For local muscular endurance: 3-5 holds of 20-60 seconds, 2-3 sessions per week, progressing hold time or load. For blood-pressure reduction, isometric exercise training trials commonly used 4 x 2-minute wall-squat holds with about 2 minutes rest, 3 sessions per week, at an individually calibrated knee angle or perceived effort."
    }
  ],
  "usage": "Evidence: moderate. Surface EMG studies of isometric wall squats consistently show the quadriceps — particularly vastus lateralis and vastus medialis — as the dominant muscles, with activation increasing as knee flexion deepens toward 90 degrees; rectus femoris contributes less than the vasti because its hip-flexor moment is unloaded by the wall support. Hamstring co-activation is low, which is one reason the wall sit is favored when tibiofemoral shear must be limited. Gluteal and trunk-extensor activity is modest and postural. Adding an isometric ball squeeze between the knees measurably raises adductor and vastus medialis activity. Separately, isometric wall-squat training has a substantial randomized-trial literature (including meta-analyses of isometric exercise training) showing clinically meaningful reductions in resting blood pressure.",
  "note": [
    {
      "text": "Press your whole back — low back included — flat into the wall."
    },
    {
      "text": "Push the floor away through your heels, as if trying to slide the wall down."
    },
    {
      "text": "Keep shins vertical: knees stacked over ankles, not drifting past the toes."
    },
    {
      "text": "Breathe steadily throughout the hold — do not hold your breath or shrug your shoulders."
    }
  ],
  "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 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": "synergist"
        }
      ]
    },
    {
      "url": "https://bodyiq.dev/fhir/StructureDefinition/muscle-involvement",
      "extension": [
        {
          "url": "muscle",
          "valueString": "Gluteus Medius"
        },
        {
          "url": "role",
          "valueCode": "stabilizer"
        },
        {
          "url": "coding",
          "valueCoding": {
            "system": "http://snomed.info/sct",
            "code": "78333006"
          }
        }
      ]
    },
    {
      "url": "https://bodyiq.dev/fhir/StructureDefinition/muscle-involvement",
      "extension": [
        {
          "url": "muscle",
          "valueString": "Adductor Group (Longus/Brevis/Magnus)"
        },
        {
          "url": "role",
          "valueCode": "stabilizer"
        }
      ]
    },
    {
      "url": "https://bodyiq.dev/fhir/StructureDefinition/muscle-involvement",
      "extension": [
        {
          "url": "muscle",
          "valueString": "Erector Spinae Group"
        },
        {
          "url": "role",
          "valueCode": "stabilizer"
        },
        {
          "url": "coding",
          "valueCoding": {
            "system": "http://snomed.info/sct",
            "code": "44947003"
          }
        }
      ]
    },
    {
      "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"
          }
        }
      ]
    },
    {
      "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"
          }
        }
      ]
    },
    {
      "url": "https://bodyiq.dev/fhir/StructureDefinition/muscle-involvement",
      "extension": [
        {
          "url": "muscle",
          "valueString": "Tibialis Anterior"
        },
        {
          "url": "role",
          "valueCode": "stabilizer"
        },
        {
          "url": "coding",
          "valueCoding": {
            "system": "http://snomed.info/sct",
            "code": "73508007"
          }
        }
      ]
    }
  ]
}