Why is heart rate variability important?
Heart rate variability can be used to obtain information regarding a person’s internal physical and emotional state. This information depends on the clinical setting. For example, in a neonatal care unit change in HRV can be used to predict sepsis before other clinical signs are observed. In patients who have had a heart attack HRV can be used to warn is another heart attack is likely. In a stressful situation HRV can give information on how a person is responding to the stress.
Over the past 20 years and in thousands of sessions I have used monitoring equipment to follow the beat-to-beat heart rate of my patients. From this extensive experience I have learned some key points:
- Heart rate variability is particular to each individual. There is no one heart rate variability that is “good” for everyone. While there are some generalities the HRV trace is unique to the individual. An HRV trace that is good in one person may not be good in another situation.
- Heart rate variability is related to the context or situation. Since the heart rate responds to physical demands as well as stress the HRV trace can be interpreted reliably only if one knows the context in which the trace was recorded. A trace that is good in one situation may indicate problems in another situation.
- Many changes in the HRV trace are not clinically relevant and need to be ignored.
- Some changes in the HRV trace are important and these changes can appear within seconds. One needs practice to spot these and most programs that analyze HRV do not have the capacity to spot such rapid changes.
How does HRV Trace use heart rate variability?
The meaning of a particular trace is related to the speed of the heart rate in beats per minute, the shape of the HRV trace, and the beat-to-beat variability within that trace.
HRV Trace displays all of these in real-time. Certain HRV traces will indicate the likelihood of you being in a recover state, or a stressed state from which you need to reset. HRV trace can also act as a guide to help you desensitize yourself to stressful conditions.
What do the different colored dots mean?
The dots are colored using symbolic dynamics, a mathematical method used to analyze heart rate and other complex systems. The black dots indicate lower variability. In the same individual and other conditions being equal, the more frequent the black dots the more sympathetic activation. Red dots indicate an accelerating heart rate with the dark red dots indicating a high rate of acceleration. Blue dots indicate a decelerating heart rate with the dark blue dots indicating a high rate of deceleration.
If you are using a recovery technique then you would want to see few black dots and a low heart rate. If you are doing a reset technique you would want to see a couple of dark blue dots in a row.
What heart rate monitors does HRV Trace work with?
HRV Trace will work with any monitor that sends RR data using standard Bluetooth Low Energy, BLE, protocols. It has been tested successfully with the Zephyr HxM Smart, the Polar H7 and H10, and the FirstBeat chest strap. The Garmin monitors appear to use a proprietary protocol and will not work with HRV Trace.
Only the Zephyr HxM Smart will send activity levels to the app. The other monitors do not have that capacity.
My heart rate seems much more erratic than it should, what does that mean?
The most common cause of an erratic heart rate is a poor connection to the chest strap. We have had some difficulties with the Zephyr chest straps giving more inaccuracies after 20 hours of use. Replacing the battery fixes the problem.
We have not had any difficulties with the app misreading the data sent. Every instance of questionable data has been from the chest strap not working properly, a low battery in the monitor, or too great of a distance for clear BLE communication.
If you are concerned about your heart rate then please see a medical professional.
I am having problems connecting to the heart rate monitor. How do I fix that?
Make sure that other iOS devices that might connect to the heart rate monitor are off or out of range. Also make sure that you do not have other heart rate monitors active that could be connecting to the app.
When someone has used multiple heart rate monitors and various other apps on their iOS device they have had to turn bluetooth off in their device settings, then put on the monitor, start the app, and then turn bluetooth on. Once the app has paired with a heart rate monitor it will remember that and connect automatically if the heart rate monitor is on and in range.
My activity level is not changing even if I am moving around. What is wrong?
Only the Zephyr HxM Smart transmits activity data. The Polar and FirstBeat monitors do not.
What is the accuracy of the heart rate and RR interval data?
The app records data using the accuracy of the heart rate monitor. The Polar and FirstBeat monitors use 1 msec accuracy for the RR interval data. The Zephyr monitor uses 4 msec accuracy.