Heart rate variability

[dime]

Recently I came across Heart Rate Variability
My gps watch supports recording of this which I can later analyze with the free Kubios HRV software (or some non-free software like Firstbeat).

On a first test it seems like my HRV values are higher than the normal, and fit around the 25 percentile of 'sportsmen' group according to a study I found.
Athletes and fit, active people have higher values in general. The values go down in case of disease, overtraining, etc. The HRV is regulated by parasympatethic and sympatethic nervous systems, and various other factors as well:

The main inputs are the sympathetic and the parasympathetic nervous system (PSNS) and humoral factors.
...
Factors that affect the input are the baroreflex, thermoregulation, hormones, sleep-wake cycle, meals, physical activity, and stress.

I need to look better at it, but in any case it seems like a more powerful and reliable general health status metric than the Buteyko 'control pause' test, although they are probably related. From what I found online, immediate HRV can be somewhat controled and imroved by synchronizing proper relaxed breathing and meditation (which makes sense, as breathing has a large effect on the parasympathetic/sympathetic nervous systems).
More reading (that I need to do as well, I'm kind of bookmarking here :))
http://www.heartmath.com/science-behind-emwave/
http://www.coherence.com/science_html_production.htm
http://www.iam-u.org/index.php/20-reaso ... you-can-do

[RRM]

Very interesting.
I should also get something that records HRV.

Maybe this one from Firstbeat (329 euro):
"It’s smaller than a matchbox, weighs a half-ounce and has researchers at the Institute of HeartMath excited about its ability to enable a new threshold of research and understanding of the power of the human heart and the effects of stress and emotions."

wearing_hrv_recording_device.jpg

Or this one (even more expensive)
"Record Heart rate and activity for up to 21 days
Record IBI for up to 440,000 beats (3.5 days @ 76bpm)
less than 10 grams
Clips onto two ECG electrodes worn on the chest
Waterproof
The new gold standard for measuring Activity Energy Expenditure"

Cardio_Chest_pads_350.jpg

[dime]

Also this one is supposed to be very good and probably cheaper (developed by one of the best researchers in the field from what I've read):
http://myithlete.com/
But I haven't looked in detail if you can record and play with the data yourself (e.g. import it in the kubios software), or it just gives you rought result, like you're under stress or not.