curl -X POST "https://api.fitsociety.io/public/v1/workout/groups/performance/sessions/{sessionId}/exercises/{exerciseIdToReplace}/replace" \
  -H "Authorization: Bearer <access_token>" \
  -H "Idempotency-Key: <stable_request_key>" \
  -H "Content-Type: application/json" \
  -d '{}'

const options = {
  method: 'POST',
  headers: {
    'Idempotency-Key': '<idempotency-key>',
    Authorization: 'Bearer <token>',
    'Content-Type': 'application/json'
  },
  body: JSON.stringify({newExerciseId: '<string>'})
};

fetch('https://api.fitsociety.io/public/v1/workout/groups/performance/sessions/{sessionId}/exercises/{exerciseIdToReplace}/replace', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

import requests

url = "https://api.fitsociety.io/public/v1/workout/groups/performance/sessions/{sessionId}/exercises/{exerciseIdToReplace}/replace"

payload = { "newExerciseId": "<string>" }
headers = {
    "Idempotency-Key": "<idempotency-key>",
    "Authorization": "Bearer <token>",
    "Content-Type": "application/json"
}

response = requests.post(url, json=payload, headers=headers)

print(response.text)

{
  "data": {
    "id": "66f7b8b1e13c8d25f4d3d90a",
    "exerciseId": "66f7b8b1e13c8d25f4d3d90a",
    "planExerciseId": "66f7b8b1e13c8d25f4d3d90a",
    "order": 1,
    "isCompleted": true,
    "date": "2026-07-14T10:00:00.000Z",
    "startedAt": "2026-07-14T10:00:00.000Z",
    "endedAt": "2026-07-14T10:00:00.000Z",
    "totals": {
      "totalReps": 1,
      "totalTimeSeconds": 1,
      "totalDistanceMeters": 1,
      "totalVolume": 1,
      "maxWeight": 1,
      "estimated1RM": 1,
      "averageRPE": 1
    },
    "sets": [
      {
        "setNumber": 1,
        "setType": "N",
        "displayNumber": 1,
        "displayLabel": "1",
        "targetReps": "8-12",
        "targetWeight": 60,
        "targetTimeSeconds": null,
        "targetDistanceMeters": null,
        "targetRestSeconds": 90,
        "weight": 70,
        "reps": 8,
        "timeSeconds": null,
        "distanceMeters": null,
        "restSeconds": 120,
        "rpe": 8,
        "completed": true,
        "notes": "Felt strong.",
        "isPersonalBest": false,
        "repsPlaceholder": 22,
        "weightPlaceholder": 30,
        "timeSecondsPlaceholder": 55,
        "distanceMetersPlaceholder": 40,
        "rpePlaceholder": 3,
        "restSecondsPlaceholder": 60,
        "repsActual": 30,
        "weightActual": 42,
        "timeSecondsActual": null,
        "distanceMetersActual": null,
        "rpeActual": 8,
        "restSecondsActual": 90
      }
    ],
    "notes": "string",
    "nextSessionTarget": {
      "reps": 1,
      "weight": 1,
      "timeSeconds": 1,
      "distanceMeters": 1
    },
    "targetSnapshot": {
      "reps": 1,
      "weight": 1,
      "timeSeconds": 1,
      "distanceMeters": 1
    },
    "setupFields": [
      {
        "key": "seat",
        "label": "Seat",
        "type": "text",
        "unit": "",
        "options": [
          "1",
          "2",
          "3",
          "4"
        ],
        "order": 1,
        "required": false,
        "enabled": true,
        "defaultValue": 3
      }
    ],
    "setupValues": {},
    "nextSetupValues": {},
    "hasMachineSettings": true,
    "setupSettingsEnabled": true,
    "isMachineSetting": true,
    "provenance": {
      "recordedByActorType": "string",
      "recordedByClientId": "66f7b8b1e13c8d25f4d3d90a",
      "recordedByCoachId": "66f7b8b1e13c8d25f4d3d90a",
      "lastUpdatedByActorType": "string",
      "lastUpdatedByClientId": "66f7b8b1e13c8d25f4d3d90a",
      "lastUpdatedByCoachId": "66f7b8b1e13c8d25f4d3d90a"
    }
  },
  "meta": {
    "requestId": "4f849d7d-f4f1-45cc-b4b7-3984a3d17f83",
    "rateLimit": {
      "limit": 10,
      "remaining": 9,
      "resetSeconds": 1
    },
    "idempotency": {
      "replayed": false
    }
  }
}