The importance of normal values
Blog post by Marco Altini
I often talk about your "normal values" as the only meaningful way to make use of Heart Rate Variability (HRV) data. But what are these normal values? Why are they important?
Simply put, your normal values are a representation of your historical data. They allow you to understand if acute (daily) and chronic (weekly) HRV responses are showing meaningful changes or just small variations that you should not worry about.
Normal values make the data actionable.
Why do we need normal values? This has to do with the high day to day variability in HRV data. It might be easier to show this with an example. Let's look at the data below. This is typical HRV data, there is much variability between consecutive days.
Should the highlighted reduction trigger concerns and adjustments in our plans or not?
Many tools will allow you to at least look at your baseline, computed as a weekly average, or smoother version of your daily HRV. Does this solve the problem? Not really, we get a better understanding of the recent value, but still, are these reductions meaningful?
The solution to these issues, is to establish your normal range, or normal values.
In HRV4Training we build your normal values based on your past 60 days of data (more info, here). There are no population values for these, you need to collect data for a while in order to be able to determine your own range.
Your normal values make it easy to capture meaningful acute drops as well as longer-term, chronic reductions below what is considered normal variability for you. This is based on what we call the Smallest Worthwhile Change in the scientific literature.
In HRV4Training, you can see your normal values for both heart rate and HRV, on the homepage. This way, you can quickly check if there were any abnormal physiological responses on a given day (acute change), or with respect to your baseline (chronic change).
This is the approach currently used by state of the art research on HRV-guided training, which I discuss in this blog. Remember that using HRV requires a mindset shift: from higher is better, to normal is better.
Outside of training, the same applies. While many tools out there started converting your physiological and behavioral data in 0 to 100 scores, physiology does not work that way, and it makes little sense to do so.
Use a tool that clearly shows you when day to day and weekly changes are outside of your normal range, to make the most of the data. A boring, within-normal HRV is ideal.
I discuss these aspects in this blog as well, in point 3, together with other considerations covering:
If you are using HRV4Training Pro, you can see your normal range visually in the baseline page as well.
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This blog is curated by
Marco Altini, founder of HRV4Training
The Ultimate Guide to HRV
1: Measurement setup
2: Interpreting your data
3: Case studies and practical examples
1. Intro to HRV
2. How to use HRV, the basics
3. HRV guided training
4. HRV and training load
5. HRV, strength & power
6. Overview in HRV4Training Pro
7. HRV in team sports
1. Context & Time of the Day
3. Paced breathing
4. Orthostatic Test
5. Slides HRV overview
6. Normal values and historical data
7. HRV features
1a. Acute Changes in HRV
1b. Acute Changes in HRV (population level)
1c. Acute Changes in HRV & measurement consistency
1d. Acute Changes in HRV in endurance and power sports
2a. Interpreting HRV Trends
2b. HRV Baseline Trends & CV
3. Tags & Correlations
4. Ectopic beats & motion artifacts
5. HRV4Training Insights
6. HRV4Training & Sports Science
7. HRV & fitness / training load
8. HRV & performance
9. VO2max models
10. Repeated HRV measurements
11. VO2max and performance
12. HR, HRV and performance
13. Training intensity & performance
14. Publication: VO2max & running performance
15. Estimating running performance
16. Coefficient of Variation
17. More on CV and the big picture
18. Case study marathon training
19. Case study injury and lifestyle stress
20. HRV and menstrual cycle
21. Cardiac decoupling
22. FTP, lactate threshold, half and full marathon time estimates
23. Training Monotony
Camera & Sensors
1. ECG vs Polar & Mio Alpha
2a. Camera vs Polar
2b. Camera vs Polar iOS10
2c. iPhone 7+ vs Polar
2d. Comparison of PPG sensors
3. Camera measurement guidelines
4. Validation paper
5. Android camera vs Chest strap
6. Scosche Rhythm24
7. Apple Watch
9. Samsung Galaxy
1. Features and Recovery Points
2. Daily advice
3. HRV4Training insights
4. Sleep tracking
5. Training load analysis
6a. Integration with Strava
6b. Integration with TrainingPeaks
6c. Integration with SportTracks
6d. Integration with Genetrainer
6e. Integration with Apple Health
6f. Integration with Todays Plan
7. Acute HRV changes by sport
8. Remote tags in HRV4T Coach
9. VO2max Estimation
10. Acute stressors analysis
11. Training Polarization
12. Lactate Threshold Estimation
13. Functional Threshold Power(FTP) Estimation for cyclists
14. Aerobic Endurance analysis
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16. Training Planning
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18. Aerobic efficiency and cardiac decoupling
1. HRV normal values
2. HRV normalization by HR
3. HRV 101