Hi Marco. Thank you for a great product and your continued writing on the subject.
I take a 1 min reading using iPhone at the same time every morning - occasionally I will redo the test if I see a HRV below baseline as I am trying to use it as a major determinant of training that day. The result is always different (to be expected?) but my concern is when the results flick between below and within baseline, like today (HRV 6.6 below, then 7.0 within).
hey Andrew, thank you for your message and support, much appreciated. Indeed I'd say this is normal, differences of 0.2-0.4 are expected for repeated measures regardless of the type of technology used (PPG or ECG, we've looked at it here: https://www.hrv4training.com/blog2/on-hrv-measurement-repeatability-what-is-the-effect-of-paced-breathing-and-measurement-duration). This being said, at times these differences can fall within or outside the normal range, and I understand this can be a bit confusing. My recommendation is first to minimize as possible differences that derive from small changes during the measurement, for example no swallowing saliva, no sneezing, no yawning, no movement, and a relaxed, but not forced, breathing. These simple steps increase reliability. Additionally, you could also measure for two minutes if you have the time, which also removes a bit of variability, even though 1 minute is typically fine (that is also what I use). The goal of the protocol is always to result in a comparable data point with respect to previous and following days, not necessarily with other moments of the same day. So if we wake up, sit up, take a measurement, then we should ideally do the same when we measure again (at least the sitting up part, as otherwise the protocol slightly differs). Unless you experience something different during the first measurement - which can happen, e.g. you have some negative thought, and you can even see your heart rate increasing in the app - then I normally recommend not double testing, as we are hardly ever in the same exact state. If you do spot an issue, then simply go with the second measurement, in which you were e.g. able to relax again. Eventually, these small differences motivate also the more recent approaches to HRV-guided training, where baseline changes - instead of daily changes - are used to determine the best course of action for the day. This means that you need several days of suppressions before you implement a change, as many low HRV days will lead to a baseline below your normal range. If you have Pro you can see the normal range also in the Baseline page of the app, otherwise you can still compare the Baseline to the normal range in the homepage of the app, as the numbers are all reported there. In real life I think that a combined approach is best, i.e. there are days in which we just feel poorly (sick or else) and it wouldn't be wise to wait another 4 days before we implement a change :) Both acute and baseline changes eventually matter, but if you feel good, I would not typically worry about a low reading. I'd proceed as planned and see how it feels during training as well as if I bounce back the day after. In that case, it's all good. I hope this provides some useful pointers, thank you again!
Hi Marco. Thank you for a great product and your continued writing on the subject.
I take a 1 min reading using iPhone at the same time every morning - occasionally I will redo the test if I see a HRV below baseline as I am trying to use it as a major determinant of training that day. The result is always different (to be expected?) but my concern is when the results flick between below and within baseline, like today (HRV 6.6 below, then 7.0 within).
Any advice? 🙏
hey Andrew, thank you for your message and support, much appreciated. Indeed I'd say this is normal, differences of 0.2-0.4 are expected for repeated measures regardless of the type of technology used (PPG or ECG, we've looked at it here: https://www.hrv4training.com/blog2/on-hrv-measurement-repeatability-what-is-the-effect-of-paced-breathing-and-measurement-duration). This being said, at times these differences can fall within or outside the normal range, and I understand this can be a bit confusing. My recommendation is first to minimize as possible differences that derive from small changes during the measurement, for example no swallowing saliva, no sneezing, no yawning, no movement, and a relaxed, but not forced, breathing. These simple steps increase reliability. Additionally, you could also measure for two minutes if you have the time, which also removes a bit of variability, even though 1 minute is typically fine (that is also what I use). The goal of the protocol is always to result in a comparable data point with respect to previous and following days, not necessarily with other moments of the same day. So if we wake up, sit up, take a measurement, then we should ideally do the same when we measure again (at least the sitting up part, as otherwise the protocol slightly differs). Unless you experience something different during the first measurement - which can happen, e.g. you have some negative thought, and you can even see your heart rate increasing in the app - then I normally recommend not double testing, as we are hardly ever in the same exact state. If you do spot an issue, then simply go with the second measurement, in which you were e.g. able to relax again. Eventually, these small differences motivate also the more recent approaches to HRV-guided training, where baseline changes - instead of daily changes - are used to determine the best course of action for the day. This means that you need several days of suppressions before you implement a change, as many low HRV days will lead to a baseline below your normal range. If you have Pro you can see the normal range also in the Baseline page of the app, otherwise you can still compare the Baseline to the normal range in the homepage of the app, as the numbers are all reported there. In real life I think that a combined approach is best, i.e. there are days in which we just feel poorly (sick or else) and it wouldn't be wise to wait another 4 days before we implement a change :) Both acute and baseline changes eventually matter, but if you feel good, I would not typically worry about a low reading. I'd proceed as planned and see how it feels during training as well as if I bounce back the day after. In that case, it's all good. I hope this provides some useful pointers, thank you again!