Multisport Coach API
AI coach that creates personalized training plans for runners, cyclists, swimmers, and triathletes. This skill provides access to workout plans, performance metrics, AI coaching, and plan adaptation. Powered by Transition.
Authentication
Authenticated endpoints require the TRANSITION_API_KEY environment variable. Pass it as the X-API-Key header on every request. If it's not set, tell the user to generate one in the Transition app under Settings > API Keys.
Base URL: https://api.transition.fun
Free Endpoint (No Auth Required)
Workout of the Day
Generate a random structured workout. Each request returns a different workout.
curl "https://api.transition.fun/api/v1/wod?sport=run&duration=45"
Parameters:
sport — run, bike, swim, or strength (default: run)duration — minutes, 10-300 (default: 45)
Response:
{
"date": "2026-02-09",
"sport": "run",
"name": "Tempo Builder",
"description": "Build aerobic endurance with sustained tempo efforts",
"duration_minutes": 45,
"intensity": "moderate",
"segments": [
{"name": "Warm-up", "duration_minutes": 9, "intensity": "easy", "description": "Easy jog to warm up"},
{"name": "Tempo", "duration_minutes": 27, "intensity": "moderate", "description": "Steady tempo at comfortably hard pace"},
{"name": "Cool-down", "duration_minutes": 9, "intensity": "easy", "description": "Easy jog to cool down"}
]
}
Authenticated Endpoints
Get Workouts
Retrieve scheduled workouts for a date range.
curl -H "X-API-Key: $TRANSITION_API_KEY" \
"https://api.transition.fun/api/v1/workouts?start=2026-02-09&end=2026-02-15"
Parameters:
start — Start date (YYYY-MM-DD, required)end — End date (YYYY-MM-DD, required)- Maximum range between
start and end is 90 days.
Get Workout Details
curl -H "X-API-Key: $TRANSITION_API_KEY" \
"https://api.transition.fun/api/v1/workouts/123"
Generate Workouts
Trigger AI workout generation for the user's training plan.
curl -X POST -H "X-API-Key: $TRANSITION_API_KEY" \
-H "Content-Type: application/json" \
"https://api.transition.fun/api/v1/workouts/generate"
Adapt Workouts
Adapt the training plan based on recent performance or schedule changes.
curl -X POST -H "X-API-Key: $TRANSITION_API_KEY" \
-H "Content-Type: application/json" \
-d '{"reason": "feeling fatigued after race weekend"}' \
"https://api.transition.fun/api/v1/workouts/adapt"
Check Generation Status
Poll whether workout generation/adaptation is complete.
curl -H "X-API-Key: $TRANSITION_API_KEY" \
"https://api.transition.fun/api/v1/workouts/status"
Performance Management Chart (PMC)
Get CTL (fitness), ATL (fatigue), and TSB (form) data.
curl -H "X-API-Key: $TRANSITION_API_KEY" \
"https://api.transition.fun/api/v1/performance/pmc"
Performance Stats
Get FTP, threshold paces, heart rate zones, and other metrics.
curl -H "X-API-Key: $TRANSITION_API_KEY" \
"https://api.transition.fun/api/v1/performance/stats"
AI Coach Chat
Chat with the AI endurance coach. Returns a streaming response (SSE).
curl -X POST -H "X-API-Key: $TRANSITION_API_KEY" \
-H "Content-Type: application/json" \
-d '{"message": "Should I do intervals today or rest?"}' \
"https://api.transition.fun/api/v1/coach/chat"
Chat History
curl -H "X-API-Key: $TRANSITION_API_KEY" \
"https://api.transition.fun/api/v1/coach/history"
Athlete Profile
curl -H "X-API-Key: $TRANSITION_API_KEY" \
"https://api.transition.fun/api/v1/profile"
Push Workout to Garmin
curl -X POST -H "X-API-Key: $TRANSITION_API_KEY" \
"https://api.transition.fun/api/v1/workouts/123/push-garmin"
Rate Limits
| Tier | Read Endpoints | AI Endpoints |
|---|
| Free | 100/day | 3/day |
| Paid | 10,000/day | 100/day |
Read endpoints: workouts, metrics, profile, history
AI endpoints: coach chat, adapt, generate
Rate limit errors return HTTP 429 with a message indicating which limit was exceeded.
Tips for Agents
-
Check fatigue before recommending hard workouts. Call GET /api/v1/performance/pmc and look at TSB (Training Stress Balance). If TSB is below -20, the athlete is likely fatigued — suggest easier workouts or rest.
-
Use adapt sparingly. Plan adaptation regenerates the entire training plan using AI. Only trigger it when the athlete explicitly asks for changes or when there's a significant reason (injury, schedule change, race date change).
-
Use the free WOD endpoint for casual users. If someone just wants a quick workout without signing up, use GET /api/v1/wod. No API key needed.
-
Workout generation is async. After calling POST /workouts/generate or POST /workouts/adapt, poll GET /workouts/status until it returns ready, then fetch the workouts.
-
Date format is always YYYY-MM-DD for all date parameters.
