HRV Ithlete FAQ for athletes
Recently the Tri Training Harder Coaches had the privilege of listening to Simon Wegerif, founder of ithlete, to pass on his knowledge of HRV to our coaches. Simon is the leading figure on HRV, and its impact on athletes. Below we summarise the answers to some of the critical questions we asked. If you want to find out more about HRV and how it can be used in your training, check out Coach Jon’s Blog or head over to myithlete.com.
What is HRV?
Heart Rate Variability is the measure of the small differences in the time between each heartbeat. Usually, it is calculated from the time between each of the peak R peak values on the ECG (eg rMSSD).
HRV shows the balance between sympathetic (fight or flight) and parasympathetic (rest and digest) nervous systems. The higher the value, less sympathetically stressed the athlete is – in other words, the less on edge they are. As we know, stress comes in more forms than just training, and as a result, our body carries our cumulative stress. HRV is a great way to investigate if your body is carrying stress from other, unmeasurable sources.
Is measuring HRV the same as measuring resting heart rate?
HRV is more sensitive to an imbalance between stress and recovery, and moves earlier than resting heart rate, which better reflects changes in aerobic fitness. However, as with all data, if you review both, you have a better chance of picking up more meaningful information.
What units is HRV measured in?
The units are usually milliseconds. However, to make the readings easier to interpret, companies can apply some maths to make things comparable. With ithlete, they take the log (rMSSD) x 20.
Why Use log (rMSSD) x 20?
Using the natural logarithm of HRV multiplied by 20 means the units and the magnitude are comparable to heartrate data and you could compare them against one another on the same scaled axis. Reviewing the data on these scales means the more athletic the person, the greater separation between the resting heart rate values and the HRV values.
How should I measure my HRV? What time of day, and position is best for taking HRV readings?
It is best to measure your HRV as one of the first things you do in the morning. For athletes, it is suggested that you get more reliable readings when you sit up. You also need to ensure that you keep a regular breathing rate up, so in the ithlete app follow the paced breathing guide.
What is the most accurate sensor? (inc why can’t I use my Fitbit / Garmin / Apple watch etc.)
Because this is technically a medical reading, the more accurate the sensor, the better information you have. Bad data in, means bad data out. So, to be the most accurate, it is worth using the right sensors. Heart rate straps validated for HRV are the best option, and the next best are validated finger sensors (c£44). Back of the wrist (watches/wearables) or back of the phone camera is not accurate enough to get the best data.
Do I have to take a reading every day?
No, you don’t but as with all of these sort of things, the more regularity you have, the quicker you can see trends. HRV will react quicker than other metrics, but the more data you have, the more apparent it is. The recommendation is most days or at least every training day.
What does the number mean? (i.e. the specific calculation)
The actual number, when calculated out, is a measure of how different your time between heartbeats is—the higher, in general, the better. However, to bring more meaning to the data, it is best to compare the daily reading with the rolling 28-day baseline. In other words, you want your HRV daily value to be higher and generally close to your rolling average. When you start having values outside of this normal range, then you need to assess why. Tools such as ithlete Pro go a step further and will help you to identify the likely causes.
If the trend line is trending negatively, it can be a sign that you are stressed, overtraining or have an oncoming illness.
If my HRV reading is low, should will I not perform?
No, if your reading is low, you are may still perform well. However, it is an indication that your balance between your parasympathetic and sympathetic stress systems is out, and you need to balance this additional stress with a little more recovery. Alternatively, look at improving your recovery.
Can I fudge my data?
Yes, if you slow your breathing down. However, you should look at breathing about 7.5 breaths per minute which is average for endurance athletes. It also means consistent readings from day to day.
How can my Coach see my data?
A coach can see your data through an ithlete Coach Account on and also the data can be automatically pulled into Training Peaks.
Can I exchange my data with Training Peaks?
Yes, however, you will need an ithlete Pro account for the sync to work.
Should I take my HRV when I am racing?
In general, on race day, you will feel a level of arousal and excitement about racing. Your fight or flight feelings will, therefore, be significantly overpowering (think back to the times you have had butterflies in your stomach or felt nerves before a race). As a result, your HRV reading for the day is likely to show as a bad result. Knowing this, there is little value in seeing the negative score before the big day! In the lead up to the race, the HRV scores should be rising.
Should the data rule me?
As a coach, this is a common question – we see athletes not believe they could push over a hill with the group because their power numbers were beyond their threshold. So there can be a level of paralysis as a result of data. Therefore, as with all data, this is information and should be used as such. If you see the HRV baseline trending lower, but you are in a big training block, you may actually decide to push on, but do so cautiously, if however, there is a sudden change. You are feeling low in mood, or fatigued, then perhaps you should listen to the data. As with all things, use data to guide your decisions, not force them. Hopefully, this may be an objective realisation for athletes who sometimes struggle with knowing when to ease up.
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If you’re planning your next season, just starting out in the sport or are looking for extra guidance at the very top end of the field, we are here to help, and our coaches would be delighted to hear from you. You can contact us via the website, and one of the team will be in touch.