Numbers to know, part 2

I’m asked a lot which metrics are the most pertinent to longevity, and how someone can really get a sense of where they stand health-wise. Here is a continued list from my last post (in no order) of 5 numbers I would consider important to know:

3. Blood pressure

This is one that everyone knows matters and may seem less “exciting,” and while I will try not to harp on it too much, it cannot be emphasized enough how much it matters. Cardiovascular disease is the most devastating of all the chronic killers, as well as arguably the most preventable. That’s why our highest-yield tactics for longevity will always involve targeting modifiable risk factors like blood pressure, blood sugar, and blood lipids (LDL/cholesterol).

Of these measurements for heart health, it appears blood pressure specifically may be the strongest predictor of risk for cardiovascular mortality, as has been clearly demonstrated through the Framingham Heart Study, and more recently the SPRINT and STEP trials. In fact, all this recent data has pushed organizations like the American College of Cardiology and American Heart Association to become even more aggressive with their guidelines, which now consider a blood pressure below 120/80 to be considered normal, and above to be elevated. An elevated blood pressure is harmful on several fronts. In short, it causes mechanical damage primarily to the lining of blood vessels, which can have effects on both large-vessel and small-vessel disease. This means that not only can it lead to the major events we all first think of (i.e. heart attacks, strokes), but it can also result in significant damage in those organs particularly sensitive to blood flow, such as the kidneys or the eyes.

Hopefully everyone is convinced enough that monitoring blood pressure is of utmost importance, so let’s discuss how to track it and then how to modify it. It’s best to monitor blood pressure regularly at home as often as you’re willing, and track your results over days or weeks that you take it so you can see trends over time. Each time, you also want to take at least two readings and record both due to variability in measurement. In terms of logistics, a manual cuff measurement has actually been shown to be more accurate than an automatic, but the price of a stethoscope and ability to use it can perhaps be limiting to some (although I assure you the technique is pretty simple to learn if you want to give it a go), and the automatic cuffs are still rather accurate on the whole. You must be consistent with a few things when taking blood pressure: be resting for 5 minutes before taking it, sitting with your back supported, both feet on the ground, legs not crossed, arm at heart level, empty bladder, no exercise, caffeine, or smoking in the 30 minutes prior, and an appropriately sized cuff that doesn’t go over clothes.

Blood pressure can be affected significantly by non-modifiable things like age, sex, race, and genetics, but there are numerous modifiable risk factors to address before seeking alternative measures like medications. One of the strongest risk factors for hypertension is obesity, and oftentimes significant reductions in blood pressure are seen with weight loss. On a slightly related note is diet’s association with blood pressure, although this largely seems due to the proportion of potassium intake to sodium intake (higher is better for most people, as we often consume diets high in sodium and low in potassium), not necessarily the calorie balance or general metabolic principles we think of with causing obesity (although these likely still contribute). Exercise is of course critical for blood pressure maintenance, with aerobic appearing more beneficial than strength training, yet both still have an impact. Another major risk factor for hypertension is alcohol consumption, and while mechanisms are not entirely clear, it may be due to alcohol’s destruction of our sleep, which also independently appears to regulate blood pressure. This may be due to general immune/inflammatory-modifying actions of sleep, as well as its regulation of parasympathetic vs. sympathetic nervous system activation (more on this later). All of these modifications might not seem new, but it goes to show how they often work on several fronts to promote longevity, and must each be viewed as critical components of our wellness.

4. VO2 max

Just about the strongest single number we have for predicting someone’s risk of all-cause mortality is their VO2 max, or the maximum amount of oxygen someone can use during peak exertion. If you’re finding it tough to conceptualize just how much this metric matters, think about it this way: one study stratified the population into five groups from “low” to “elite” VO2 max, and the hazard ratios (or difference in mortality benefit) in almost every group-to-group step-up (i.e. going from low to below average, below average to average, etc.) were greater than the hazard ratio from not smoking vs. smoking. Said another way, it’s like every group or “level” you jumped up in terms of your VO2 max were the equivalent magnitude of quitting smoking on your mortality risk. And remember, smoking has long been considered among the greatest if not the greatest modifiable risk factor for a whole host of chronic diseases, so this should truly highlight the impact of improving VO2 max on longevity.

This strength of association is due to VO2 max’s reflection of multiple crucial bodily systems all functioning at their best. In order to consume the most amount of oxygen possible, we have to have the best-functioning respiratory system we can to efficiently inhale and absorb all of it into our bloodstream, the best-functioning cardiovascular system to deliver the oxygen to our tissues effectively, the best-functioning cellular metabolism to uptake and utilize all of that oxygen for fuel consumption, the best-functioning neuromuscular system to fully recruit all of our muscle fibers and push ourselves to our true max effort, etc. If any one of these systems is not in tip-top shape, the effect will be shown on our VO2 max; that’s why it’s so good at assessing all of them. If someone has an elite VO2 max, we can be confident that each of these components is functioning at an elite level, or else their performance would suffer.

Now, measuring VO2 max properly can be a little tricky, but fortunately we have some okay approximations. The best way to assess VO2 max is with a treadmill test in an exercise physiology lab. You are pushed to your limit of all-out effort, wearing a mask that measures concentrations of oxygen and carbon dioxide in the air you breathe in and out, which can accurately determine precisely how much oxygen is being utilized for this peak state of metabolism. A new, conveniently mobile, accurate, yet still wildly-unaffordable option is a mask called the VO2 Master, which we hope will drop in price in coming years, as it could become a fantastic option for better personal tracking of this critical health metric. After these options, there’s a steep drop-off in accuracy of measuring VO2 max, but it is estimated with wearable devices like the Apple Watch, albeit with limitations. Other crude approximations even include calculators based on the time it takes one to run 2 miles, which actually has a reasonable association with actual measured VO2 max.

Though it may be tough to know your exact VO2 max number without arranging a test, you can absolutely still take steps to improve it. Broadly speaking, this number is going to be a reflection of the total exercise you do. Intuitively, it is most greatly improved by high-intensity exercise, and thus lots of efforts have gone into determining the optimal interval protocol for boosting VO2 max. We tend to favor a 4-minute on, 4-minute off high-intensity interval training (HIIT) protocol for 5 cycles (40 minutes total), once or twice a week, although truthfully the evidence that this is necessarily the “best” is not very strong. Most HIIT protocols or very high-intensity exercise regimens performed once or twice a week are highly likely to have VO2 max benefit. Additionally, other high-intensity efforts like strength training appear to confer benefit, as well as even lower-to-moderate intensity training like zone 2 cardio. This also makes sense as our aerobic fitness, our mitochondrial function, is foundational to our overall cardiovascular fitness; it helps to have a wide base of a pyramid to get a higher peak. In general, for VO2 max, there is no getting around that the solution is really exercise. Of all the arguments we cite, this may be the principal one for exercise being the biggest tool we have in the toolkit for a longer, healthier life.

While I planned on wrapping up all 5 of my list in this post, I felt I really had to do justice to the topics of blood pressure and VO2 max given just how important they both are. Also, truthfully the fifth metric of the list will be the biggest “wild card” of it, but it’s one that I truly value, and I think assesses some unique health components otherwise not accounted for with this list. Stay tuned for my next post where I outline this last metric, why I put so much emphasis on it, and some other honorable mentions that didn’t technically make this “top 5,” but that I’d still consider fundamental to understanding our long-term health.

Subscribe to our monthly newsletter

Support our community projects

DISCLAIMER:

All content and information provided on or through this website is for general informational purposes only and does not constitute a professional service of any kind. This includes, but is not limited to, the practice of medicine, nursing, or other professional healthcare services. The use of any information contained on or accessed through this website is at the user’s own risk. The material on this site or accessible through this site is not intended to be a substitute for any form of professional advice. Always seek the advice of a qualified professional before making any health-related decisions or taking any health-related actions. Users should not disregard or delay in obtaining medical advice for any medical condition they have, and should seek the assistance of their healthcare professionals for any such conditions.