6 days ago
Is CRF the Vital Sign You're Ignoring?
This transcript has been edited for clarity.
If you want to maximally lower your risk of death, what is the single most important health metric to focus on? The evidence is clear, and the answer is cardiorespiratory fitness, which I'm going to abbreviate as CRF.
Despite its name, CRF is about much more than the heart and the lungs. It's about the integrative ability of multiple organ systems to support whole-body exercise.
The relationship between CRF and mortality risk has been studied numerous times. We're going to talk about one study by Mandsager and a few other authors. This study involved 120,000 people. At the start of the study, everyone performed an exercise treadmill test, and they were assessed for medical conditions. As a result of the treadmill test, they classified individuals into one of five different CRF groups, with one being the lowest and five being the highest.
Because some people, unfortunately, died during the eight-year follow-up period for this study, the researchers were able to compare the risk of death for medical conditions relative to different CRF groups. The study found that someone with diabetes or with a history of smoking had about a 40% greater risk compared to someone without those not surprising.
What is surprising is that, when the lowest CRF group (group one) was compared to group two, CRF group one — the lowest fitness group — had a 95% greater risk of death relative to those who were slightly more fit than them in group two. This single result indicates that having a very low CRF, in the bottom 25th percentile, is worse for your health than a history of smoking or having diabetes.
Let's spin this more positively, though. A different way of looking at it is that individuals in group two had a 50% lower risk of death than those in CRF group one. People in group five, who were at the highest CRF level, had an 85% lower risk of death than those in group one. The individuals in the study that had the highest CRF level, those in group five, had what looked to be an 85% lower risk of death than those in group one.
The data from this and many other studies support the same conclusion. The higher the CRF, the lower the risk of death. Full stop.
Not enough doctors or patients understand how important CRF is for their overall health. This is a problem that we need to work on solving. In my opinion, no other topic in healthcare has a greater potential to improve health at both the population and the individual level.
