Have I ever mentioned how much I like The Economist as a publication? Back in my days on Wall Street, I used to think The Economist was too highfaluting for regular usefulness. It seemed to delve into the esoteric aspects of geopolitics and global economic issues that seemed less than fully connected to the practicum that mostly interested me. That has all changed dramatically for me in retirement. I now read the publication religiously, but more importantly, find it a treasure trove of valuable general life information…not just economics. This morning I read a piece titled The Most Useful Indicator of your Overall Health. That would be a show-stopping title for anyone my age, but seems especially so for someone who is where I am these days. I had already weighed in (a new low today…achieved after a string of new lows this week) and taken my blood pressure (good reading, but a tad higher since I dropped the dose of my last remaining hypertension med). The number I have been particularly paying attention to in the last six months is pulse rate since the medication cocktail that was up to no less than 5 (Ramipril, Carvidilol, Hydralazine, Clonodine and Bemetinide) was driving my BP down, but also driving down my pulse rate. I have a naturally low pulse rate (that’s one of my genetic strengths apparently), but it was sitting in the 40s and would occasionally tip into the high 30s, which no one thinks is a good thing. As I have gradually dropped the Carvidilol, Hydralazine, Clonodine and half of the Ramipril dose as my weight has come off, I have seen my BP drop well below normal (106/58) and my pulse rate inch up to the mid-50s, all of which seems good. The Ramapril that has stayed, seems the most impactful and as I cut the dose in half I have seen my BP and pulse rise. So, you see, I am monitoring everything attentively, so hearing that there might be a “most useful” indicator that I’ve been missing really caught my interest.
To cut to the chase, The Economist article said that a metric category currently attracting particular attention is heart-rate variability (HRV). HRV measures not how quickly the heart beats, but how regularly spaced those beats are. With heart rate a lower score is usually better, since it suggests a high level of cardiovascular fitness. But I know the limitations on that, right? When it comes to HRV, though, a higher number—that is, a more irregular pattern—is generally what you want. HRV measures the variation in time between consecutive heartbeats. Counterintuitively, a more variable heartbeat is healthier — you don’t want a metronome-like heart. Your heart rate isn’t perfectly steady. Even at rest, the gap between beats fluctuates by milliseconds. HRV captures this variability, which is controlled by the autonomic nervous system — specifically the balance between your sympathetic (“fight or flight”) and parasympathetic (“rest and digest”) branches. As for why variability equals health, high HRV means your nervous system is flexible and responsive, able to shift smoothly between activation and recovery. Low HRV indicates the system is stuck in a more rigid, stressed state — often dominated by sympathetic activation. Think of it like suspension on a vehicle: you want it to flex, not be rigid.
All else being equal, stress on the body boosts the sympathetic nervous system, decreasing HRV. All sorts of stress count, whether psychological or physical. A hard workout will cause HRV to fall for hours (or sometimes days) as your system recovers. So will lack of sleep, a cold, a failing marriage or worries about money. Higher HRV is a sign of an autonomic nervous system that is in good shape, and a body that can adapt itself to the stresses of life. It is associated with a lower risk of heart attacks, and a higher chance of survival if you do have one. It is also associated with slower progression of dementia, less inflammation, a lower chance of suffering depression, and more.
So what influences HRV the most? It’s remarkably sensitive to lifestyle factors like sleep quality (poor sleep tanks HRV quickly), alcohol (even moderate consumption suppresses it significantly), exercise (intense training temporarily lowers it; chronic aerobic fitness raises baseline), stress (psychological stress shows up clearly and quickly), illness (HRV drops before you even feel sick, making it a useful early warning signal), and recovery status (athletes use it to gauge readiness to train hard). Measurement used to traditionally be done with a chest ECG or chest strap (gold standard), but modern wrist wearables like my Apple Watch estimate it with varying but reasonable accuracy. The key metric is called RMSSD (the Root Mean Square of Successive Differences) between beats. Higher is better. But absolute numbers vary enormously between individuals, so what matters most is your trend over time, not so much comparing yourself to others. If your HRV is consistently trending down over weeks, something is off (overtraining, poor sleep, chronic stress, or early illness). A single day’s reading is less meaningful than the pattern. Many athletes use it as a daily readiness score to decide whether to push hard or go easy in training. For someone like me, tracking my health closely, it pairs well with the other metrics I’m monitoring. It gives me a window into how well my body is actually recovering and adapting, not just how hard I’m working.
HRV declines naturally and significantly with age, so expectations need to be calibrated accordingly. The typical ranges for men 70-75 put the average RMSSD for men somewhere between 20-40 ms, with the broad “normal” window being roughly 15-50 ms. By comparison, a healthy 35-year-old male might average 50-70 ms, so the decline with age is substantial. At age 72, the charts say I should be consistently above 35-40 ms, which would be considered quite good for my age group. Above 50 ms would be exceptional (likely indicating strong cardiovascular fitness, good sleep habits, low chronic stress, and no significant underlying conditions). Below 20 ms warrants attention, particularly if it’s trending downward. Apparently, aerobic fitness is the dominant driver. It has a larger effect on HRV in older adults than almost any other single variable. Beyond that, sleep quality, inflammation management, alcohol intake, and stress all play meaningful roles. Medications common in this age group (beta blockers in particular) can significantly suppress HRV readings, which makes interpretation trickier. At this point, I’m off all beta-blockers (Ramipril is an ACE-inhibitor), so, for me, a consistent HRV in the 35-50+ ms range would reflect good autonomic health.
I’ve never known about or looked at HRV on my Health App on my iPhone/Apple Watch, but decided this morning to look at it. What I saw, based on my research as stated above, pleased me. I’m not sure where this was six months ago before I started my weight and exercise program, but as of today (prior week), my HRV is running 40-110 and trending upward. OK, so now I have another metric to track and so far, I’m feeling good about my program and my pounding heart.