Connecting your intervals.icu account

Takes about a minute.

Why connect it?

The 42Runs app uses intervals.icu, a free training platform, to push your planned workouts straight to your Garmin, Polar, Suunto, Coros, or Apple Watch — and to read back your recovery data (fitness, fatigue, form) so your plan can adjust to how your training is actually going. You only need to do this once.

Step 1 — Create a free intervals.icu account (if you don't have one)

Go to intervals.icu and sign up. Already have an account (e.g. from Garmin/Strava syncing)? Just log in instead.

Step 2 — Find your Developer Settings

Once logged in, click your name in the top-right corner, then Settings. On the Settings page, look for Developer Settings in the menu on the left — or go directly to intervals.icu/settings and scroll down.

Step 3 — Copy your Athlete ID and API Key

On the Developer Settings page you'll see two values:

• Athlete ID — starts with a lowercase i followed by numbers, e.g. i123456.
• API Key — a longer string of letters and numbers. If you don't see one yet, there's usually a button to generate it.

Copy each one carefully — an extra space at the start or end (easy to pick up accidentally when copying) is the most common reason a connection fails.

Step 4 — Paste them into 42Runs

Back in the 42Runs app, paste the Athlete ID and API Key into their matching fields and tap Connect. That's it — 42Runs will confirm the connection right away.

Step 5 — Connect your watch brand to intervals.icu

42Runs talking to intervals.icu is only half the chain — intervals.icu also needs to talk to your actual watch. If you haven't already linked Garmin, Polar, Suunto, or Coros there (e.g. because your account was brand new), go to intervals.icu/settings/connections and connect your device brand. Already syncing from before (e.g. via Garmin/Strava)? You can skip this step.

Still stuck?

Email us at contact@42endurance.com and describe exactly where it goes wrong (a screenshot helps a lot) — we'll sort it out with you directly.