Connect your heart rate monitor to your iPhone via Bluetooth for accurate insight into your heart rate. By connecting your heart rate monitor to your iPhone, you can train on heart rate without purchasing a sports watch. With a heart rate monitor, you measure your heart rate more accurately than with a heart rate sensor in a smartwatch. A heart rate sensor or monitor is often found on a chest strap and you wear it around your chest. You can easily download suitable apps such as Wahoo Fitness, Runkeeper, Endomondo, and Runtastic via the App Store. This allows you to analyze your heart rate measurements.