Connect Intervals.icu to ChatGPT

ThresholdLink is a remote MCP server that connects your Intervals.icu account to ChatGPT. Once it is connected, ChatGPT can read your training while you chat and add planned workouts, races and notes to your Intervals.icu calendar. There is nothing to install and no API key to copy.

What you can ask

Ask the way you would ask a coach who has read every file. For example:

• “Why did Tuesday’s intervals feel so hard?” ChatGPT compares the session’s power and heart rate with earlier ones and with your HRV, resting heart rate and sleep.
• “How’s my fitness trending before the race on the 23rd?” It reads your fitness, fatigue and form (CTL and ATL) and your calendar.
• “How much time did I spend in zone 2 over the last four weeks?” It adds up time in zones across your activities.
• “Has my 5 km pace improved since spring?” It reads your pace curve. Cyclists can ask the same of their power curve.
• “Build me 4×8 min at threshold for Thursday and put it on my calendar.” It sets targets from your zones and adds the planned workout to Intervals.icu, which syncs it to Garmin, Wahoo, COROS and other devices.
• “Plan next week around my long run on Sunday.” It reads your fitness, recent sessions and calendar, proposes a week and, once you confirm, adds all the workouts in one go.
• “Compare today’s 5×6 min with the last ones.” It lines up every repeat of the session side by side: work pace or power, heart rate and drift.

ThresholdLink reads your activities (including intervals, laps, heart rate, pace, power and time in zones), fitness, fatigue and form, wellness (HRV, resting heart rate, sleep and weight), athlete settings and zones, power and pace curves, and your calendar, and it can compare repeats of the same session. The only things it writes are planned workouts, races and notes on your Intervals.icu calendar: it adds workouts one at a time or up to 14 at once, adds races and notes when you ask, and can change or delete the workouts, races and notes it added itself. It never changes or deletes anything else in your calendar or your activities.

Set it up

OpenAI has changed how custom MCP servers are added to ChatGPT more than once. Which ChatGPT plans can add them, and what they are allowed to do, is up to OpenAI and your workspace settings.

At the time of writing, OpenAI’s documentation describes this flow in ChatGPT on the web:

1. Open Plugins in ChatGPT.
2. Choose the + button, then Add custom MCP server.
3. Enter ThresholdLink as the name and https://thresholdlink.app/mcp as the server URL under Connection.
4. Choose OAuth as the authentication.
5. Read OpenAI’s warning about custom MCP servers and choose I understand and want to continue.
6. Choose Create as a plugin, install it from your plugins and start a new chat. When ChatGPT asks you to sign in, follow the steps in the next section.

Source: OpenAI’s guide Add custom MCP server, checked in November 2026. In a Business or Enterprise workspace, an admin may need to allow it first.

What happens when you sign in

1. ThresholdLink’s consent page. ChatGPT opens a ThresholdLink page that lists what ThresholdLink reads and what it writes. HRV, resting heart rate, sleep and weight are health data, so it asks for your explicit consent with a checkbox.
2. Intervals.icu. You log in to Intervals.icu and approve access for ThresholdLink there. Your Intervals.icu password stays with Intervals.icu.
3. Back in ChatGPT. ThresholdLink is connected and ChatGPT can use it. At no point is there an API key to copy.

From then on, ThresholdLink keeps only your Intervals.icu athlete ID and an encrypted access token. Training and health data is fetched live when ChatGPT asks for it, held in memory for at most 15 minutes and never written to disk. The privacy policy has the details.

How to disconnect

• Ask ChatGPT. Say “disconnect ThresholdLink”. ThresholdLink revokes its access at Intervals.icu and deletes your athlete ID and all tokens.
• In Intervals.icu. Revoke ThresholdLink’s access in your Intervals.icu settings. ThresholdLink deletes your connection as soon as it learns of the revocation.
• By email. Write to privacy@thresholdlink.app and we delete it for you.

Removing ThresholdLink from your plugins in ChatGPT only stops ChatGPT from using it, so disconnect first if you also want your connection deleted on our side. Connections that have not been used for 12 months are deleted anyway.

More

Using Claude? See Connect Intervals.icu to Claude. Questions about data, limits and cost are answered in the FAQ. If something does not work, see Troubleshooting.