I want to make the case today that one’s cardiorespiratory fitness (CRF) should be considered a “vital sign”: akin to those measures of bodily function; temperature, blood pressure, heart rate, and respiratory rate that we routinely measure to assess our patient’s health status.
Previously, on the skeptical cardiologist, I made the case that a patient’s physical activity as measured by the minutes spent in moderate to vigorous physical activity per week (MVPA) should routinely be assessed by PCPs and cardiologists.
That post reviewed methods physicians and patients can use to assess current fitness levels, begin a fitness program, and gauge performance using wearable activity monitors relative to activity guidelines.
If CRF is a vital sign akin to blood pressure we need 1) an accurate and easily accessible method for estimating it plus 2) a database showing where we stand in comparison to others our age and gender and 3) Evidence showing that if CRF is improved by exercise then lifespan and health span are improved.
I have described in detail how to perform the simplest of these: the Rockport walking test which was developed in 1987 and has been utilized and validated widely.
The Rockport protocol requires you to walk on a level surface outdoors as fast as possible for one mile. You need some measure of the distance walked and some measure of time to do this. Wearable activity monitors will provide both. Record your heart rate during the last quarter of the walk along with the duration of your walk and enter them into the regression equation I describe here.
As a man advances from 20 to 80 years of age, his MVO2 drops precipitously from 46 to 17 ml/kg/minute leaving him with less than half of the cardio fitness he had when he graduated high school. Similarly, a woman drops from 37 to 15 ml/kg/minute.
But note that there are 10% of 70 year olds who have an MVO2 of 29, which is superior to 20% of 30 year-olds.
Regular exercise training is your major tool to make sure you have enough fitness to stay highly functional into very old age.
You can do a Cooper 12 min test or similar.
The Cooper test is simple: run as fast as you can for 12 min on a flat surface then record the distance and use those formulas:
VO2max = (35.971 x distance in miles) - 11.288
VO2max = (22.351 x distance in kilometers) - 11.288
validity: Cooper (1968) reported a correlation of 0.90 between VO2max and the distance covered in a 12 min walk/run.
You can also do a Cooper 1.5 miles (2.41km) test.
Run 1.5miles (2.41km) as fast as you can then use that formula:
Yes, I’ve seen the Cooper run test here and have been meaning to go to a track and try it. At 70, I don’t really do much running anymore but I feel physically capable of doing it. Fast walking seems more “dignified” at my age, and I do walk fast up a steep hill everyday. I can get my heartbeat (with a Polar H10) up over 200 BPM (knock on wood). I run a little at the end.
PS: And I’m at 6,200 feet elevation.
I am certainly acclimated to the altitude after so long. And I assume my Polar H10 is accurate. It’s shown over 200 BPM a number of times but I just try to hit a maximum and then rest, so just for a moment. Doesn’t feel stressful, just good healthy exercise, good heart workout, clean sweep of the arteries. If I had any discomfort, I would think twice about it.
I still haven’t taken a lab VO2 max test but would like to. And my exercise routine, cardio and weights, is consistent but fairly minimal. My resting heart rate is high, never going below 60 BPM.
It might be just a physical quirk. I’d much rather see a high VO2 max score.
Polar make very good HRM’s. I have a little tip for you. If you use an iPhone. You can get a decent assessment of your Heart Rate Variation (HRV) via your Polar HRM with an iphone app. I use the free version of “Elite HRV” but there are few around. It gives a few useful heart stats, in particular HRV (variations within heart beats). I’ve used both a Polar and Garmin HRM and it gives good analysis. Good luck!
Yes, thanks, I use Elite HRV. Since i don’t have a watch, I’m using the Polar H10 for sleep, HRV and exercise. I have an android phone. Haven’t quite figured out the all the different things that cause HRV to change…sometimes it seem that just my body position during the reading affects it.
I used a Polar H10 for about a year, but I switched about 4 weeks ago to the Morpheus band and app. It’s the model that Peter Attia pushes (I know, I know…), but I’ve found it to be really effective. You take an HRV reading every morning and enter sleep (I use the Oura ring actual time slept) and a few other subjective metrics (soreness, etc.) like with other HRV apps, but then it gives you custom HR zones for the day. Once a week it tells you how much recovery, conditioning, and intense training time you need to achieve whatever goals you had specified. It also tells you calories burned as with Polar, and the company owner claims that Morpheus is more accurate. I’ve found that following the guidelines has improved my sleep and even strength training performance because I’m not over or under doing it. When my “recovery score,” which is indexed to 100, is low, I do more recovery activities and don’t push too much. It really seems to be a game changer for me.
