The key to getting good measurements is the finger placement and amount of finger pressure applied. We recommend using two hands, the left to hold the phone, and the right to cover the camera gently (see illustration below).

  1. Gently “pinch” the back camera and flashlight with your right index finger. Use your right thumb to support your finger and stabilize measurements.
  2. Make sure that your index finger is covering BOTH the camera and flashlight. Your finger should be glowing red/pink.

  3. Make sure that you are not pressing against the camera too hard because this will restrict blood flow to your finger.

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  1. Go to Cardiio > Settings > Apple Health. Tap on it and swipe the slider next to heart rate to green to grant the app permission to sync, then tap 'Done'.
  2. Save a new heart rate measurement using the Cardiio app (Make sure you wait around 20 seconds for the Save prompt to appear).
  3. Check for your data:

    Launch Apple Health > Tap on 'Health Data' > 'Vitals' > 'Heart Rate' > 'Show All Data'

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To use the Calorie-burn calculator, you need to measure your heart rate after you've exercised, tag it as an "Active Heart Rate" (choose "Active" in the Save prompt when your heart rate measurement is complete), and enter an exercise duration (in minutes). In addition, you'll need to have a recent Resting heart rate measurement for a baseline.

Please check to make sure the settings are right:

  1. Go to “History” to access your raw data.
  2. Tap into a specific day to see the individual measurements.
  3. Make sure that they are correctly labeled as "Rest" or "Active" (you can change the label by swiping).
  4. For "Active" measurements, make sure that you've entered the exercise duration. Tap on the number to change it.
  5. Once completed, return to the "Insight" screen.

If you have "Active" measurements recorded today, your calories should be displayed. NOTE: If the measurements were in the past 7 or 30 days, you need to swipe the top gray panel ("TODAY") to the left to view them.

Other things to consider:

  • If the message "calories unavailable" appears, it means that you need to measure your Resting Heart Rate and save it.
  • If the message "active heart rate too low" appears, it means that the amount of physical exertion was not high enough to estimate caloric burn

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The free version of our app is supported by offer promotions and ads. You can disable this by upgrading to the full PRO version or the in-app purchase “Remove Ads/Rewards” item. Once you’ve upgraded, go to Cardiio > Settings> Display Rewards and turn the switch off.

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Go to Cardiio > Settings > Restore purchases, then tap on it. You'll be prompted to enter your Apple ID and password. Once Apple has verified your previous purchase, the features should be unlocked.

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  1. Launch the Cardiio app, go to "Settings" and scroll down to "Options" and you'll see the button for RunKeeper (it should say "Not configured" unless you're already connected).
  2. Tap on the RunKeeper button and enter your account details to login.
    ** Note: Don't login via Facebook! In the current release there is an issue with the RunKeeper Facebook login. As a workaround, simply use the email address registered with your Facebook account, along with your RunKeeper password to login instead.
  3. Grant Cardiio permission to be paired with your RunKeeper account. The RunKeeper button should now say "Authorized".
  4. You're all set. Now your heart rate measurements will be automatically posted to your RunKeeper feed!

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Yes! Cardiio is a universal app and is fully optimized on all iPads with a front-facing camera.

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Yes! Although Cardiio was designed primarily for dual-core iOS devices, it will still run on single-core devices with a front-facing camera (iPhone 4, iPod Touch 4G). Performance may be less robust and therefore you'll need to pay extra attention and follow these tips [link] to ensure accuracy.

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Yes! Our studies have included people of different skin color. The algorithm looks for small transient changes in color due to blood volume changes, not at the overall skin color. However, always pay attention to the following tips [link] to ensure accuracy.

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Here are some very important tips:

  • Be in a well-lit area so your face is well illuminated.
  • Make sure your face is clearly visible (e.g. no long hair covering your forehead etc.) so that it can be easily detected.
  • Don’t have a bright background behind you (backlight) - it makes your face appear dark in contrast.
  • If you're using an iPhone, fold one arm across your chest and rest the other arm that’s holding your phone against it to provide support and reduce motion of the phone during measurement.
  • Look ahead and hold the phone in front of you (approximately 6 inches or the length of your palm) instead of looking down at the phone - this allows more light to illuminate your face.
  • Hold your iPhone/iPad steady and keep still during the measurement.

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Sometimes it takes some experimenting to learn the best way and distance to hold your iPhone/iPad. Here are some important tips:

  • Be in a well-lit area so your face is well and evenly illuminated.
  • Make sure your face is clearly visible (e.g. no long hair covering your forehead etc.).
  • Don’t have a bright background behind you (backlight) - it makes your face appear dark in contrast.
  • Hold your iPhone/iPad approximately 6 inches (around the length of your palm) from your face to fill the entire red circle.

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There are a couple of possibilities:

  • The time interval between each heartbeat varies. This is completely normal and is known as heart rate variability.
  • If you just completed some vigorous activity, your heart rate will change as it recovers to your baseline.
  • If the initial heart rate estimates are incorrect, the app will continuously update the number as accuracy improves. The final number at the end of the measurement should be the most accurate.

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Please send us an email: info [at] cardiio.com and we'll be glad to help.

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