The funny thing is I read about HRV 20 odd years ago while reading ‘Chaos’ by James Gleik. This book had a large influence on my science thinking, even though at the time I was just an unemployed bum who had never even attended university. Later I became interested in HR measurements in general regarding endurance training. Then by pure chance an associate of mine that studies spinal cord injury was measuring HRV in spinal cord injured humans. This re-sparked my interest in HRV and it is a fascinating topic that has many real world applications for everybody (at least a easily measured indicator of overall health of both brain and body).
Over the next few days I will update my previous two HRV posts with some more recent research.
What you have to need to know for background (if you don’t read the previous two posts) is that HIGH HRV is good, low HRV is bad (in general).
Even young subjects with diabetes have lower HRV compared to healthy age matched controls (Javorka et. al., 2008). If this effect is seen in young subjects I would only imagine it gets worse with age.
High frequency HRV (driven by the parasympathetic system) was reduced in obese patients with myocardial infarction compared to non-obese myocardial infarction patients (BMI greater or equal to 30, which a very percentage in developed countries) (it was previously shown that in general obese patients have lower HRV). Interestingly, waist circumference was a better correlate to reduced HRV than body mass indies (BMI). This better link with waist size with reduced HRV could be tied into an increase of visceral fat (Piestrzeniewicz et. al., 2008).
In a Swiss study examining 1,712 randomly chosen subjects 50+ years old, from another bigger study, the researchers report that HRV is lower in obese subjects. HRV was higher in normal weighted subject that exercised (2 or more hours per week) (compared to normal weighted subjects that didn’t exercise), but also HRV was higher in obese subjects that exercised (compared to those that didn’t) (Felber Dietrich et. al., 2008).
Take home message
Diabetes, metabolic syndrome, and obesity all lead to a lower HRV (which remember is a predictor of shorter lifespan). However, even in obese subjects if they exercised they improved (increased) their HRV. My suggestion is by measuring your HRV (by first establishing a baseline measurement then following it over the years) you might be able to catch something (pre metabolic syndrome, pre diabetes, a harmful weight gain (even though for this one we have easier measurements)) before they reach too far and take appropriate steps to improve your HRV (e.g. exercise and diet choices).
Tomorrow more about how HRV measurements can give us a window into the mind.