Hi Edu, 

If Post HRV recording is done immediately after the exercise, then you might get a  sympathovagal imbalance with predominant sympathetic dominance . better to wait till  the recovery time to start the recording.

Thank you Jim and Arun for your answers, so i understand that you prefer measuring HRV post exercise when sympathetic activity is expected to be low, it means no immediately after exercise, isn't it?. So that, we would be analysing HRV in the period of time when parasympathetic activity is predominant in order to compare the values with a pre exercise recording when parasympathetic activity is predominant too. However, we couldn't get information about parasympathetic reactivation if we do it this way.

Hi Edu and All,

My answer is: why don't you measure the HRV all long the exercise and after? Then you can select any wanted segment to nail down the ANS activity according to your need.

This is possible using CODESNA_HRV software which is the only SW providing the ANS dynamics whatever used protocol. No more limitations related to the "5 minutes" stationarily and stability required by LF/HF method.

I attached a plot of ANS dynamics from HRV before, while and after a jogging you can see what's happening with ANS (sympathetic and parasympathetic activities) for the entire record duration.

Of course, CODESNA_HRV allows also the traditional LF/HF analysis + RMSSD but the CODESNA dynamic method (non linear math method) is not based on the spectral analysis.               

You can have look at overall SW capabilities here: http://www.codesna.com/en/products/codesna_hrv/ .

I hope this helps !

Hi Vasile, thank you for your response. As far as I reviewed the problem with HRV during exercise is not only a methodological limitation regarding analysis, it is as well the interpretation of parameters in this situation. For example, it has been signaled that HF at rest represents around 90% vagal activity, however during exercise this band is contaminated by different noise resource (breathing,...), diminishing the contribution of vagal activity to the power of HF band analyzed. For this reason, exercises that exceed the second ventilatory threshold present an elevation of HF power, while vagal activity is expected to be lower at this moment. 

May be CODESNA HRV could help in post exercise HRV recovery dealing with the issue to analyze immediately after exercise. The question here is, it is worthy analyze this period of time or it is better make it when the HR is close to baseline values?

Hi Edu,

My point was also related to the various markers and theirs interpretation, not only to the methodology the study. To me, the methodology is related to "what" you are looking for and markers represent the "how" you are doing it.  And those are supposed to be independent. Driving your methodology based on the markers limitations (so the "what" is driven by "how") is already a contamination and an artificial orientation of any study. Because you are predicting (or excluding) something based on markers behaviour you have seen before. For instance, you mention "it has been signalled that HF at rest represents around 90% vagal activity...". This is a good example of a statement that is very easy to challenge. At rest, if breathing frequency is low (e.g. 6 cycles/min), all the power is falling in LF band while physiologically body is supposed to be in a parasympathetic state (so HF should be dominant in that case according to the "1996 LF-HF" dogma). Please see this thread, it might be interesting here: https://www.researchgate.net/post/How_can_I_interpret_HRV_analysis_in_autonomic_response_to_slow_breathing.

Another point that surprises me a bit is: "...during exercise this band is contaminated by different noise resource (breathing,...), diminishing the contribution of vagal activity to the power of HF band analyzed".

For me, breathing is a major physiological component of autonomic regulation loop so why considering it like "noise"? If it's because it "contaminates" the HF band, this is a "bad" scientific reason for me since it means you're looking to satisfy markers again.

To overcome mathematical limitation related to LF-HF method we bring, at CODESNA, new ANS markers easy to understand and interpret. Without any limitations on your protocol, length or methodology you can figure out ANS dynamics and averaged sympathetic and parasympathetic activities. Then you can select the "post-exercise" duration or segment from physiological interest only and from what you targeted as aim of the study. .    

I also recommend an excellent study here that revisit the ANS behaviour during exercise:  http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4080933/

Hi Vasile, 

I am open to understand new interpretations of parameters of HRV, however I would like to see first an experiment where these parameters are re-interpreted using the new methodology that CODESNA brings.

Until now, what already it is reported is that breathing has a non neural influence on HRV during heavy exercise....

Non-neural influence of breathing during exercise: http://www.ncbi.nlm.nih.gov/pubmed/18621862

And LF can not be identified enteriley as a sympathetic marker, what I agree with you difficult assume the "1996 LF/HF dogma"

LF is not a sympathetic marker: http://www.ncbi.nlm.nih.gov/pubmed/21890520

However, I can't wait for reading the new solution you comment me.

Best regards.

Edu

Hi Edu,

Thanks for your scientific curiosity!

A first study done evaluating CODESNA markers was done by Pr. Laurent Mourot (in French only for now, sorry) is here: http://www.codesna.com/en/scientific-comitee/

He will submit a short version for publication soon, other studies are ongoing with hospitals and Faculty of Medicine here in France.   

Please find here the document explaining CODESNA markers with some examples : http://www.codesna.com/wp-content/uploads/guide-utilisateur/User_Guide_CODESNA_HRV.pdf

There are some scientists starting to publish that indeed LF band is not necessarily sympathetic. Moreover, I observed in some cases, HF band is not necessarily parasympathetic either, please check this use case here: https://www.researchgate.net/publication/282853251_Case_study_on_HRV_-_Real_time_monitoring_of_meditation_shows_surprising_results  

To me, LF and HF are markers that vary with physiological conditions but using them as SNS and PNS activities is an extension that I'm not buying. Since mathematically is not appropriate and this "works" only if subjects breath above a given frequency. Surprisingly, so many mathematical and physiological limitations of the method are practically not challenged, excepting a few.                 

Please see the attached a case study of a paced respiration at 6 cycles/min (at rest) where you can see 0.1Hz peak so practically all the power being folded in LF band. This short example compares the LF/HF with CODESNA markers.

Please note that my aim is not to bring a new method for research only, we want to deliver (and we do) valuable physiological information to the people we are measuring (physiological imbalances like chronic stress, resting factor...etc). It's a result of several years of research.  

You are very welcome to evaluate the SW by yourself, is very easy to download, install and check it out using your own HRV files. If you have any questions related to the method,

I'll be happy to discuss more with you on the subject, either here or over email.

Cheers,

Vasile

Research Case study on HRV – Real time monitoring of meditation shows...