HRV is the variation in the time interval from one heartbeat to the next. It can be used as an indicator of physiological stress.
Most people think of heart rate as the average number of beats per minute, but your heart rate changes from beat to beat. HRV measures this naturally occurring irregularity in heart rate. The more variation in the interval between beats, the lower your physiological stress level.
Ava measures the ratio between low frequency and high frequency waves in your heart rate. Scientific studies have shown that the HRV ratio is a good indicator to assess the balance between the sympathetic nervous system and the parasympathetic nervous system. An imbalance in these systems—usually when the sympathetic branch takes the upper hand—is associated with high physiological stress level and results in a high HRV ratio.
Estrogen and progesterone have an impact on HRV. The HRV ratio is increased during the luteal phase when progesterone peaks, compared with the follicular phase, when estrogen is high.
Normal HRV ratio varies widely from person to person, but by looking for an increase or decrease from your baseline HRV ratio, you can learn about your body’s physiological stress level. HRV ratio is complicated, but the important thing to remember that a higher HRV ratio indicates higher stress.