Perhaps someone has wondered whether HRVTs based on DFA a1 are still aligned with established standards when tested at altitude. It's not an unreasonable question, and one where adverse consequences could occur. I remember a trip to 6500 ft altitude in my younger days and even trivial exertion was surprisingly difficult. Well, we now have some data about DFA a1 behavior at altitude that I would like to share:
Before getting into the details, I would like to thank my co-authors and especially Juan and Youmna. It was a great fun working with the data, exploring HRV physiology under hypoxia and of course, the teamwork interactions.
One last point before you read through the file - although not part of the headline, a major highlight of this study is the tight correspondence of both the HRVT1 and HRVT2 with the GET/RCP. This reinforces our belief in the "custom" method of HRVT1 derivation.
You may notice some emphasis on the importance of preprocessing, notably detrending. I must thank one of our reviewers for that, they asked and I provided the explanation below:
Summary points:
- This study showed excellent alignment of HRVTs with gas exchange standards with normoxia.
- The new "custom" HRVT1 was confirmed to be valid.
- Hypoxia related HRVTs were still aligned, but there was much more "scatter". Variable hypoxic related ANS response was probably a factor.
- Detrending does matter, as does signal quality.
