THE APP NEEDS A BLUETOOTH LE HEART RATE MONITOR.

Heart rate variability is literally the variance over time between beats of your heart. So if your heart rate is 60 beats per minute, it doesn't actually beat once per second. Within that minute there may be 0.9 seconds between two beats, for example, and 1.15 seconds between two more. The greater this variability, the more "ready" your body is to perform high-level activities.

When you start using a heart rate variability monitor, you may notice that your HRV varies greatly from day to day. This can be attributed to the many factors that influence it, and it is perfectly normal. If your friend has a higher HRV than you today, that doesn't indicate he's fitter than you.

Rather than comparing heart rate variability with others, a more practical use of HRV is to follow your own long-term trends. For example, if you are taking steps to improve your fitness and overall health, you should see a gradual increase in your average heart rate variability over time.

Studies have shown that heart rate variability can be a valuable tool for making the most of your training. After days of strenuous activity, your HRV will drop. With adequate rest and recovery, your heart rate variability will increase, letting you know when it's time to push again.

Changes in heart rate and HRV are always individual, which is why you should get tested regularly to establish your individual baseline. To make sure the results are as reliable as possible, you need to test under similar conditions every time - we recommend that you take the test in the morning before breakfast.