intervals.icu is the bridge, and it carries two things. Out: the session Summit planned for you, which intervals.icu forwards to every device you have linked there. Back: your night — heart rate variability, resting heart rate, sleep — which is how a watch or band that does not write to Apple Health still gets you a recovery score. It does not carry your rides; those reach Summit through Strava, or straight from a Karoo.
1 · Create the account
Go to intervals.icu and choose Sign Up Free. Register with an email and password, or sign in with Strava or Garmin Connect — any of the three works.
If you sign up with Garmin Connect, that device is already linked and step 2 is only about its two boxes. With any other device, you link it in step 2.
2 · Connect your device, and let it take workouts
In intervals.icu, open Settings → Connections. Every device connects from that one page. Connect the one you train with, and check two things on it:
- Planned workouts go out. This is the box that puts Summit's session on the device: Upload planned workouts. It is unticked when you connect. Without it, the session reaches your intervals.icu calendar and stops there.
- Wellness comes in. The box next to it downloads wellness data — sleep, HRV, resting heart rate — from your watch or band into intervals.icu, which is what Summit reads back. It is unticked too.
Strava is on that page too. It cannot take a planned workout or send wellness data, so it is not the connection that matters here.
Which devices take a workout
On intervals.icu's Connections page (checked 28 Sep 2026), the devices with an Upload planned workouts box are Garmin Connect, Wahoo, Coros, Suunto, Amazfit, Huawei Health and Zwift. MyWhoosh reads the intervals.icu calendar as soon as you connect it, with no box to tick. Polar, Oura, Whoop and Google Fit only send wellness data: useful for your recovery score, but the session does not reach them.
3 · Connect it in Summit
In Summit: Settings → Integrations → intervals.icu. It is free on every plan. You log in on intervals.icu's own screen, so Summit never sees your password. That screen lists three permissions:
- Calendar. To write your session into your intervals.icu calendar. It is the only thing Summit sends.
- Wellness. HRV, resting heart rate and sleep — your recovery score.
- Activities. The screen asks for it too, but Summit does not import your rides from intervals.icu.
4 · Send today's session
On Summit's Today screen, open the session and tap Send to intervals.icu. Summit confirms it landed in your intervals.icu calendar, and it reaches your device the next time the device syncs.
It is one tap, for today's session: nothing is sent on its own. If the plan adapts after you sent it, send it again — it replaces the session already in the calendar rather than adding a second one.
Done
Your wellness data comes back on its own from here: after your first full night you get a recovery score. Give it a week before you argue with that score — it reads against your own baselines, and it needs a few nights to learn them.
If the session does not reach your device
Look at your intervals.icu calendar first. If the session is there, the planned-workout upload from step 2 is off for that device, or the device has not synced yet. If it is not there, send it again from Summit; if Summit says the intervals.icu limit is reached, wait the minutes it shows. Still stuck: team@projectsummit.app, and say which device you train with.
A Hammerhead Karoo does not need any of this — Summit talks to it directly. More on what happens to the data in the FAQ.