Intervals Companion

About

Intervals Companion is a full-featured iOS and watchOS companion for Intervals.icu. It brings your fitness data to iPhone, Apple Watch, iPad, and Mac with glanceable widgets, deep health integration, and automatic two-way sync between Apple Health and Intervals.icu.

Viewing Your Data

Browse your training load, fitness, fatigue, and form at a glance. View detailed activity breakdowns, performance charts, best efforts, workout plans, and wellness trends — all sourced live from your Intervals.icu account. Configurable home screen, lock screen, and Apple Watch widgets keep your most important metrics always visible and update automatically in the background. Silent push notifications trigger refreshes whenever new activities or wellness data arrive on Intervals.icu, so widgets stay current without manual intervention.

Follow other athletes on Intervals.icu and browse their recent activities in a scrollable feed. Tap into any activity to see full details, charts, and performance data. Keeping up with training partners and seeing how others are progressing is a great source of motivation alongside your own training.

Chat

Stay connected with your coach and training group through Intervals.icu's built-in chat. Read and reply to messages directly from the app, with conversations organized by channel. Push notification alerts are delivered in real time when new messages arrive, so you never miss an update from your coach or teammates — even when the app is closed.

Workout Management & Apple Watch

Planned workouts from Intervals.icu can be viewed, managed, and sent directly to Apple Watch. Scheduled workouts appear in the app with full step-by-step structure, and can be pushed to the watch for guided execution — including target power, pace, or heart rate zones for each interval. After completing a workout on Apple Watch, the recorded data syncs back to Intervals.icu automatically.

Intervals.icu → Apple Health

Activities recorded on connected devices are automatically written to Apple Health as workouts, keeping your Health app complete. Supported sources include Garmin, Zwift, Wahoo, MyWhoosh, Rouvy, Hammerhead, and TrainingPeaks Virtual.

Apple Health Workouts → Intervals.icu

Workouts recorded natively on Apple Watch or in any Apple Health-connected app can be synced back to Intervals.icu automatically. The app monitors Apple Health in the background and uploads new workouts as FIT files, complete with heart rate, GPS, cadence, and other available data streams. This makes it easy to get Apple Watch workouts into Intervals.icu without a separate device connection.

Apple Health Metrics → Intervals.icu

Daily wellness data is read from Apple Health and synced to your Intervals.icu wellness log automatically each morning. The following metrics are supported (each can be individually enabled or disabled in Settings):

Heart: Resting heart rate, HRV (SDNN and rMSSD), sleeping heart rate, Baevsky Stress Index
Sleep: Total sleep, sleep stages (light, deep, REM), breathing disturbances, sleep score
Body: Weight, body fat %, waist circumference
Activity: Steps, active energy, basal energy, VO₂ max
Vitals: Blood oxygen (SpO₂), respiratory rate, blood pressure, blood glucose
Nutrition: Calories consumed, hydration, protein, carbohydrates, fat
Scores: Readiness score, sleep score (see Score Logic)

Syncs run in the background using HealthKit background delivery, so your Intervals.icu wellness log is updated without opening the app.

Make sure to enable background app refresh and notifications to take full advantage of automatic syncing and widget updates.

Contact

If you have an idea for a feature, a bug to report or need help, feel free to reach out:

intervalscompanion@icloud.com

Frequently Asked Questions (FAQ)

1. Why are my Strava activities missing from Intervals Companion?

If you're using Strava as your data source for Intervals.icu, your activities may not appear in Intervals Companion.
This is due to Strava's data policy, which prevent third-party apps like Intervals Companion from accessing detailed activity-level data through the Intervals.icu API.

To fix this:

Go to your Intervals.icu account settings
Connect your services directly (e.g., Garmin, Wahoo, Zwift, etc.)

This ensures that full activity data flows into Intervals.icu and becomes visible in Intervals Companion.

➡ More details in this forum thread.

2. Why is my form data in the app different from the website?

Both the Intervals.icu website and the app allow you to choose how your Form is calculated:

Absolute value: Fitness - Fatigue
Percentage: (Fitness - Fatigue) / Fitness

Make sure the setting in the app matches your preference on the website. You can find this setting in the app under Settings > Fitness Settings > Form Calculation.

3. Why do I get a ‘data streams 403 error’ when viewing activity details?

This error is caused by the Intervals.icu backend stream data API endpoint getting out of sync with your authentication token.

To fix this:

Open the app settings
Tap the Full Logout button
Log back in again

This will generate a new authentication token and resolve the issue.

4. What is the HRV widget?

The HRV widget helps you understand how your current heart rate variability (HRV) compares to your recent trends. It shows where your HRV falls within your 60-day average, adjusted by the standard deviation.

Top box (1): Your HRV value for today.
Bottom box (7): Your average HRV across the past 7 days.

Each box is color-coded to quickly indicate whether your HRV trend is improving, stable, or declining compared to your 60-day range.

This can be disabled by going to Settings > Fitness Settings > Show HRV Trend on Fitness Screen.

Privacy Policy

Intervals Companion does not collect, store, sell, or associate personal data with any other service.

The app stores your Intervals.icu Athlete ID, which is paired with Apple’s randomized device identifier. This is used exclusively to send silent push notifications through Apple’s Push Notification Service, allowing the app to refresh your data in the background automatically.

This process is required by Apple and ensures secure and efficient background updates