An AI coach that plans your season, adapts to real life, and manages your training — all through conversation in Claude Desktop.

Built with Claude and connected to intervals.icu, this isn't a workout generator. It's an ongoing coaching relationship that understands periodisation, knows your data, and adjusts when life gets in the way.

Plans your season — Build a periodised training plan working backwards from your A-races. Base, build, peak, taper — structured across months with appropriate load progression.

Adapts week to week — Work trip? Illness? Injury? The plan flexes. Not by throwing it away and starting again, but by making intelligent trade-offs that protect your key sessions.

Creates real workouts — Properly structured sessions that land directly in your intervals.icu calendar. Warm-ups, intervals, recoveries, cool-downs — all syntactically correct and ready to execute.

Learns as you go — Every conversation builds context. Your FTP, your injury history, your preferences, how sessions felt. You don't start from zero each time.

You chat with your coach in Claude Desktop. A dedicated Claude Project becomes your coaching space — every conversation within that project is a conversation with your coach, with full access to your training data and calendar.

The coach operates at multiple levels:

Read your training data:

• Current zones, FTP, threshold HR, threshold pace
• Planned workouts on your calendar
• Completed activities with full metrics (power, HR, zones, training load)
• Daily wellness and recovery data (resting HR, HRV, sleep, fitness/fatigue/form)

Manage your calendar:

• Create new workouts with full structure
• Update existing sessions (intensity, duration, intervals)
• Move or delete workouts
• Swap sessions between days

Coach intelligently:

• Discuss session purpose and execution cues
• Validate training zones against physiological markers
• Make load trade-offs when adapting plans
• Flag concerns proactively (fatigue, injury risk, session conflicts)

Here's the kind of thing you can ask your coach:

Season planning:

• "I've got a middle-distance triathlon on June 15th. Can you build me a 16-week plan working back from that?"
• "I can only train 8 hours a week until March, then I'll have more time. How should we structure this?"
• "My bike is weakest. Can we weight the plan towards cycling while maintaining run fitness?"

Weekly adjustments:

• "I'm travelling for work on Thursday — can we move that session?"
• "I'm still feeling rough from that cold. What should I do this week?"
• "Yesterday's threshold session felt easy. Should we adjust my FTP?"

Session management:

• "Add a 90-minute endurance ride to Saturday"
• "Make tomorrow's VO₂ session a bit shorter — I'm tired"
• "What's on my calendar for next week?"

Review and analysis:

• "How did last week's training go?"
• "Review my last training block — what worked and what should we change?"
• "Am I ready for a step-up week or do I need more recovery?"

• Node.js v18 or later
• Claude Desktop with a Pro subscription
• An intervals.icu account with API access

# Clone the repository
git clone https://github.com/dballinger/triathlon-coach.git
cd triathlon-coach

# Run the installer
./install.sh

The installer will:

1. Prompt for your intervals.icu API credentials
2. Build the MCP server
3. Build the workout skill
4. Configure Claude Desktop automatically

After installation:

1. Restart Claude Desktop
2. Add the workout skill (Settings → Skills → Add Skill, select packages/skill/dist/intervals-workout-skill.zip)
3. Create a new project and paste the contents of project-instructions.txt into the project's custom instructions

That project is now your coach. Every conversation within it is a conversation with your personal triathlon coach, with full access to your intervals.icu data.

1. API Key: Go to https://intervals.icu/settings → scroll to "API key" section
2. Athlete ID: Found in the URL when logged in (e.g., i12345 from intervals.icu/athletes/i12345)

If the automated installer doesn't work for your setup, see Manual Installation below.

Edit project-instructions.txt to adjust:

• Threshold terminology (LT/CP vs LT1/LT2 vs VT1/VT2)
• Metric preferences per sport (power, HR, pace)
• Analysis preferences
• Communication style

Edit packages/skill/workout-preferences.md to change:

• Default target types per workout type
• Warm-up structures (e.g., openers for high-intensity sessions)

After editing, rebuild the skill:

cd packages/skill
./build.sh

Then remove the old skill in Claude Desktop (Settings → Skills) and add the new zip file.

triathlon-coach/
├── README.md
├── install.sh                     # Automated setup
├── project-instructions.txt       # Coaching persona & preferences
├── packages/
│   ├── mcp-server/               # intervals.icu integration
│   └── skill/                    # Workout syntax knowledge
└── claude-config/
    └── mcp-servers.json.template

cd packages/mcp-server
npm install
npm run build

Add the MCP server to your Claude Desktop configuration:

macOS: ~/Library/Application Support/Claude/claude_desktop_config.json Linux: ~/.config/Claude/claude_desktop_config.json

{
  "mcpServers": {
    "intervals-icu": {
      "command": "node",
      "args": ["/absolute/path/to/triathlon-coach/packages/mcp-server/build/index.js"],
      "env": {
        "INTERVALS_API_KEY": "your_api_key",
        "INTERVALS_ATHLETE_ID": "i12345"
      }
    }
  }
}

cd packages/skill
./build.sh

Then: Claude Desktop → Settings → Skills → Add Skill → select the zip file.

Create a new Claude project in Claude Desktop. Copy project-instructions.txt into the project's custom instructions.

This project is now your coach. Start a conversation and begin planning your season.

Contributions welcome. Please feel free to submit issues or pull requests.

MIT