Start by opening your iPhone's settings and select Bluetooth.

First, activate your Bluetooth to allow the sensor to be detected by your iPhone.

Once your Bluetooth is activated, your Shapeheart sensor appears in the detected devices. Select it to pair it with your iPhone.

Then open your Runkeeper app from your main menu and follow the instructions below.

At the bottom left, select the "Me" icon.

Then at the top right, the app settings.

In these settings, go to the "Apps, Services & Devices" section.

Then in "Manage Devices" and select "Heart Rate Monitor".

While Runkeeper searches for the monitor, reactivate your Bluetooth. The Shapeheart sensor flashes blue on one side and flashes green on the other once paired with the app.

To display your heart rate on Runkeeper, start a run and long-press one of the data squares, then switch to heart rate.