The single research backed variable that will make you live longer

By: June 11, 2020

When my six year old son Luke is constructing an elaborate lego model he sometimes needs to locate a single see through transparent, tiny 1 by 1 piece in his giant box of accumulated pieces from past projects. I swear it’s like trying to find a grain of sand in Pangaea before continental drift (yes we are pandemic home schooling geography).

His self-created go to strategy when he gets frustrated sees him spill out the entire box contents and spread them over the floor. He will then stand up over top and declare he is taking a ‘birds eye view’. He is shockingly successful using this strategy.

Recently I read a great research paper that took this same ‘birds eye view’ on mortality (your chance of dying).

Over the past 50 years, despite cardiovascular disease and cancer remaining as the two leading causes of death for men, the actual mortality rates of these diseases have dropped substantially. In fact, since 1969, all cause mortality rates in the US have declined by 43%, and much of this is attributed to a decrease in cardiovascular disease mortality.

This is great news!

Some researchers have a very pointed view on these statistics. They would state that the drop in overall mortality in men is due to the drop in cardiovascular disease and to a lesser extent cancer. They would then state that the drop in mortality from these two disease are due to improved diagnostic criteria, improved identification of risk factors, prevention guidelines and even dietary guidelines.

I would give their argument a resounding ‘YES!’

The part where they lose me is when some state that your cardiovascular fitness (essentially how good ‘shape’ you are in) does not change your risk of dying. They explain away the decrease in mortality solely to the decreases in cardiovascular disease and in cancer secondary to medical advancements in these diseases.

And then I came across this recent article in the American College of Cardiology where the researchers took my son Luke’s approach of the ‘birds eye view’.

You see in 1989 the first major study was published showing a very strong inverse relationship between fitness and subsequent all cause mortality in a large generally healthy cohort. This has been repeated so many times that the American Heart Association is advocating that ‘fitness’ should be included as a clinical vital sign the same way that your pulse rate and blood pressure are.

But since that first paper, we have seen an aggressive decrease in mortality in men. Does this association of decreased risk of death with improved cardiovascular fitness still hold true in the modern, improved medical era where we are able to screen, prevent, treat, and ultimately cure a lot of cardiovascular disease and some forms of cancer.

What the researchers did was take the data from a study conducted long ago from 1971 through 1991. They then constructed a second cohort of men and followed them from 1992 through 2014.

You may wonder why the early 1970’s for the first cohort. It was during this time period that there was a rapid drop in cardiovascular disease and cancer death. Statin drugs came to market in the 1970s (in fact in the second, more recent cohort, 12.1% were on a statin drug. This compared to a shocking 27.8% of the American adult population being on statins from 2012 to 2013). Antismoking reforms for workplaces and public spaces also occurred. Chemotherapy was shown to help survival in 1975 and subsequently cancer mortality slowly began to decline.

Among other tests, they had them complete fasting bloodwork, an electrocardiogram, and a max treadmill test performance from which they were able to derive a measure called METS (Metabolic Equivalents) which is a unit of measurement for levels of fitness based on the final speed and grade of the treadmill stratified for age. They then classified cardiovascular fitness for the men from 1 to 5 based on their performance.

As you can see from the table, as a society we are definitely trending in the right direction. These stats are the number of deaths per 1,000 man years of data. You can seefrom the first to the second cohort there is a sharp decrease in your chance of dying as well as your chance of dying from cardiovascular disease and from cancer. That’s great.

But it doesn’t explain if fitness is indeed still an important variable.

Now look at this second chart. Yes it’s a bit more ‘busy’ but here’s the basis. The first model only controls for age and smoking. You see that the more in shape a person is for cardiovascular fitness, they have a sharp decline in their changes of dying overall as well as dying from cardiovascular disease and from cancer. In model 2, they controlled for way more variables including BMI, cholesterol and blood pressure to tease out other factors. And again, your chances of dying decreased substantially the better in shape you were. This means that despite our improvements in keeping people alive with contemporary medical approaches, fitness still has a shocking impact on your chances of dying, your chances of dying from cardiovascular disease and to a lesser extent your chances of dying from cancer.

In fact, your chances significantly lower with each MET improvement on a 5 point scale. So even minimal improvement makes a huge difference.

For you numbers folks out there – each 1 MET increment in fitness was associated with a 13% decrease in all cause mortality, a 16% decrease in dying from cardiovascular disease and a 9% decrease in dying from cancer. Check it out:

While advances in medicine have had a very meaningful improvement in your longevity, your fitness level has been a mainstay as the most important modifiable risk factor. I guess the adage holds true ‘the more things change, the more they stay the same’.

Sometimes you just need a ‘birds eye view’ to see these things.

As a side note I was alerted to this study by a very renowned nutrition researcher who stated “In the age of statins, stents, SGLT2 inhibitors and procedural cures for whatever ails us, fitness is still king!…….Nothing nutrition-wise even touches these HRs” (HR’s are Hazard Ratios – a statistical method showing the effect of an intervention on an outcome).

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