The Most Important Health Metric
Turns out that your heart’s pretty important.
We know, shocking stuff. Today we’re putting our Sunday lens atop Heart Rate Variability (HRV), the metric Washing Post called “The Most Important Health Metric.” It’s a bellwether for your overall health, that’s never been easier to track, with some pretty startling implications.
It’s key to point out that your heart rate refers to the number of beats per minute, which is not what we’re talking about today.
With all that said…
A healthy heart is not a metronome.
Newsflash, if your heart beats at the same speed when you’re delivering a speech to 100 people and when you’re watching Is It Cake on Netflix, you’ve got a problem.
HRV refers to the amount of time between your heartbeats, measured in milliseconds.
The rate at which our heart beats is controlled by the Automatic Nervous System (ANS) controls our heart rate, blood pressure, breathing and digestion. It contains three parts: the sympathetic (fight or flight response; triggering a decrease in HRV), parasympathetic (relaxation response; triggering an increase in HRV) and the enteric (not being discussed today).
HRV is the clearest indicator when seeking to understand how well your body can adapt to the scenarios you’re placing it in. Essentially, improving your HRV highlights a greater equilibrium for your body. A strong HRV score suggests you’re more capable of dealing with stress – physically and mentally – in addition to giving your body what it needs to adequately recover as efficiently as possible.
Age, genes and hormones all have a massive impact on your HRV – these factors, as well as myriad others – mean that your “score” is incredibly individualistic, so comparing yours to someone else’s is unnecessary.
What *is* important though, is trying to improve your HRV.
Low HRV has been shown time and time again to correlate with future illness or death.
In a meta-analysis of 8 studies looking at 22,000 patients, lower HRV was associated with a 32-45% increased risk of a first cardiovascular event in patients without known heart disease.
Another, using UK data from 46,000 individuals in 2023, determined that "reduced HRV had a strong association with a higher risk of all-cause mortality in an adult population.”
You read that right, all-cause mortality; lower HRV = more likely to die.
A low HRV doesn’t necessarily mean something’s wrong now, but its correlation with future health implications is well documented. Given that it’s never been easier to track your own HRV, paying attention to changes in your score is quite literally a vital indicator as to how well your body’s performing its most important task: keeping you alive.
Sad To Say
It doesn’t stop with your physical though. When we said HRV is an indicator of your overall health, we meant it. Pushing some plates at the gym isn’t the only way to put yourself under stress.
Anyone who’s experienced depression knows the toll it can take on the body when it’s kicking your arse. Two separate meta-analyses looked at around 5,000 individuals and highlighted a link between depression and HRV (Kemp et al., 2010; Koch et al., 2019). Another singular study, albeit notably smaller, suggested “a direct association between the severity of [depression] symptoms and the modulation of [HRV]” (Agelink et al., 2002).
Suffice to say that your mental and physical health are inextricably linked. Yes, balancing both is a tough task, but it’s vital.
Bed Time Bevs
In researching this piece, two particular common behaviours appeared to have a real impact on people’s HRV.
The first is unsurprisingly, alcohol. The severity of the effect, however, is notable.
One small study of 148 participants compared athletes who drank with those who didn’t, and found a 22.7% reduction in the HRVs of those who chose to have a tipple.
Not only that but their change in HRV, though consistently tailing off, took five days to return to its normal level. This is due to alcohol’s ability to keep the sympathetic nervous system active for longer than it needs to be, instead of allowing your parasympathetic nervous system to kick in and help you to rest.
Sleepy Swallow
Some wearable data has highlighted a connection between eating before bed and a dip in both sleep quality and recovery score (highly influenced by HRV). They suggest this is due to your body’s inability to focus on restorative processes in favour of digestion when you opt for a late-night snack.
The suggestion is that this both stops you from falling asleep sooner (26 minutes less sleep on average), whilst also dropping recovery scores by a tenth, too.
Try and put a sock in it at least a few hours before bed. Give your gut the grace to do its thing before you try to catch some shuteye.
Soaring Scores
HRV is clearly a fantastic metric to understand your overall wellness, offering insight into recovery, adaptability, illness, fitness, as well as physical and emotional stress.
As always, the fastest routes to improving HRV include proper sleep, exercise, hydration and a varied, healthy diet. However, the emotional connection outlined above is an interesting addition to the usual wellbeing quartet.
You can Google online for an average HRV score for your age group, but ultimately comparing your number to someone else's means next to nothing. Figure out your own number over a 28-day period, then follow the advice to increase it as best you can.
We’ve seen a remarkable improvement in HRV scores from ZAAG users who track their data via wearables, with fitness fanatic Lottie Alice Lamb seeing a stonking 68% improvement after just 6 weeks of taking her daily ZAAG shot whilst maintaining her usual stacked routine.
If you haven’t copped a two-week trial pack to experience it for yourself yet, you know what to do.
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