Fitness is More Important Than Age in Predicting Longevity

In my previous post I discussed how researchers at the Cleveland Clinic associated performance on an exercise test with all-cause mortality and concluded the better your performance, the lower your risk of mortality.

Researchers also looked at the same data to determine whether estimated age based on performance on the test predicted longevity better than actual age. The conclusion was yes, it does, and the results will be published in print shortly and are now available online [1] and also nicely discussed here.

They introduce the concept “ABEST”, or age based on exercise stress testing. ABEST was determined statistically by looking at the maximum workload (METs) achieved in the test, heart rate recovery after the test, resting heart rate, and maximum heart rate. And the data clearly showed that ABEST predicts all-cause mortality better actual age. So if you are 80 and very fit you can be more likely to live 10 more years than someone who is 70 and sedentary.

This chart from the paper shows how fitness correlates with risk of all-cause mortality:

As discussed in the previous post, the fitter you are based on performance in the stress test, the less likely you are to die from any cause. This has been shown previously, for example in 2002 other researchers found every 1 MET improvement in exercise capacity correlates with a 12% improvement in likelihood of survival [2].

Heart rate recovery after the test is another indicator of fitness that correlates with better longevity. After getting your heart cranked up exercising, the fitter you are, the faster it will recover towards its resting level when you stop. This concept has been around a long time, for example it is measured in the famous YMCA step test. And it has also previously been shown in several studies (for example [3]) to correlate with mortality risk.

I think the author’s main contribution is the introduction of the single measure ABEST which can readily be extracted from readily available data from exercise stress tests. The statistics to calculate this number can be provided in an app which could allow doctors to come up with this number for their patients. “You’re 77, but based on your test performance you’re equivalent to 69, keep up the good work”, or “You’re 67, but based on your test performance you’re equivalent to 79, you need to be more physically active” .

How to get started?

If this evidence has convinced you to get more serious about lowering your “ABEST”, what’s the best way to get started? What can you do in the most efficient way to “ace” an exercise stress test? Even if you don’t have one in your immediate future, it turns out training for one is a pretty optimal way to get fit. First you have to be active enough to have a “base” of moderate activity, the equivalent of brisk walking several times a week. This confirms the typical recommendation to get about 150 minutes of moderate activity a week, which can be accumulated in formal exercise sessions or activities of daily living. This “fitness base” will give you the stamina to get you through the first half of the test. That will get you maybe a B- on the test. To ace it, you need to add a “second stage booster”, which is high intensity training. Much less volume of this is needed, like a few minutes worth a couple of times a week. The idea is to get up to about 10 METs or more in short bursts. If you routinely do that, you could readily push it up to about 12 at your max in the test and get A+! The best high intensity exercise that is a part of daily living is stairs. Climbing several flights per week briskly should do the trick. Other possibilities include running or cycling sprint training, brisk rowing or paddling, or hiking briskly uphill. Just look for something that will get you above 10 METs on a chart of activities. Although I must point out they can be maddeningly incomplete. For example the reference in the link says walking upstairs is 6 METs. At what speed? I guarantee you can get it up to 10 if you go fast enough. And they don’t give METs for biking uphill, which is a common way cyclists get good workouts. Sorry, it looks like somebody poked one one of my pet peeves. If you have a specific activity you might have to do a google search like “stairclimbing METs”.

Whatever activities you pick have to be enjoyable to make it sustainable. In my case there’s my day to day base of brisk walking or cycling. My “second stage” booster is sprinting on a biking or brisk uphill hiking a couple of times a week.

Cardiovascular Fitness Is Not Enough

The fitness measured in an exercise stress test is cardiovascular, and making sure it is high enough is a great way to improve your chances for longevity. But there are other important aspects of fitness for healthy aging. The first is muscle mass and strength, which tend to decline with age. Your cardiovascular exercise may slow this down in the muscles involved, such as your legs if you’re a runner or cyclist, or your arms if you’re a paddler. But you can still have muscle decline elsewhere. A classic example is older runners at the start of races who have well-toned legs but can look emaciated from the waist up. Two ways to prevent this are to engage in a more “whole body” activity like triathlon, or to do resistance training. Resistance training, along with weight-bearing exercise, is also a great way to fight off another serious issue, bone loss with age (osteopenia and the more severe osteoporosis). We also get a lot stiffer when we age, which can lead to an impaired gait (“old-man shuffle”) and the possibility of ending up hunched over, even in the absence of osteoporosis. Stretching training is important to fight that off, or taking classes like yoga or Tai Chi. I stretch diligently about 30 minutes each night. I just searched this site and found I have not talked about stretching enough, I’ll remedy that soon. Finally there is balance. If you find a class in “functional fitness for seniors” or equivalent at a local fitness senior it should cover all these aspects. I remember one of my aunts taking a class for seniors with the cool title “balance and bones”.

Addendum- Please see comment from susiesopinions below- I emphasized stairs as a high MET example but they may not be for everybody if they cause you something like knee pain. An activity that is pain free, enjoyable, and conveniently available is best. For example, I’m just getting over an achilles issue, and while it was healing, stairs were fine for me but walking up an incline was not. Everybody’s different.

References

1. Harb, S, et al, “Estimated age based on exercise stress testing performance outperforms chronological age in predicting mortality”, European Journal of Preventive Cardiology, 2019.
2. Myers, J, Prakash, M, Froelicher, V “Exercise capacity and mortality among men referred for exercise testing”, N Engl J Med 2002.
3. Cole, CR, Blackstone, EH, Pashkow, FJ Heart-rate recovery immediately after exercise as a predictor of mortality. N Engl J Med 1999 .