…or Cardio Pulmonary Exercise Test.
Back in 2011, my hospital purchased a machine to perform exercise tolerance tests on people who are considered an anaesthetic “high risk”. This would identify who may not be recommended for complex surgery requiring a long anaesthetic and just as importantly it would allow better planning of high dependency and critical care for closer monitoring in the post-operative period. The anaesthetist who ran the programme required some healthy volunteers of all fitness levels to help quality assure results during the initial set up (and the personnel using the tech). As I had recently rediscovered riding a bike over the previous year, I was encouraged to have a go so I did.
This involved getting on an exercise bike with ECG leads attached and a tight fitting mask to measure my heart rate and rhythm as well as the amount of carbon dioxide that I would breathe out. The computer was programmed to increase resistance over a period of time much like climbing a never ending hill without the promise of a nice breather on the descent. There comes a time when the intensity is cranked up so much that the body cannot cope with the demand and one has to stop. I am no expert on this so there is plenty of science about it to read here & here. Anyway a picture of my results 6 years ago is below.
I was pretty pleased about this as was told that my lung function was as if I hadn’t spent half of my life as a smoker and affirmed (to me at least) that I was in good shape, the best that I had ever felt. However given my peak VO2 max above my level of cardiovascular fitness looked like it was “poor” according to the charts.
Then earlier this year I came across this excellent synopsis by PedalWorks about VO2 max and this got me into thinking how to calculate my own VO2 max using the Uth-Sorensen-Overgaard-Pedersen estimation, a method to estimate this measure of cardiovascular fitness. My current resting heart rate & age would suggest this to be 50.9 making me “superior”. My recent birthday present of a FitBit could even calculate this for me and this wonderful piece of tech states that my “cardiovascular fitness is ,”between 44 & 48, excellent for a man your age!” Could it be that the last 6 years of cycling a lot had placed me in the “excellent/superior” category? And why is there a marked difference in both measurements. If my experience in critical care has taught me anything it is not to fully trust machines and estimations so when I was chatting to an anaesthetist during some teaching, she offered me the chance to hop on the CPET bike again to offer me something more tangible. After all, this is considered to be “gold standard” in calculating…
Wow! an increase in my peak VO2 max by 24% and my Lactate/anaerobic threshold more than doubled*. The lactic threshold is important if you read the first link-theoretically it means that you can go faster for longer before exhaustion when you are training to seek a marginal gain over your competitors. Or in my case, comfortably go for a longer ride without the shortness of breath bothering me too much.
They say that these results are meaningless unless you are training for a specific target as an athlete if measured regularly but they aren’t a predictor of performance. I would say that the cardio fitness helps in sport in general as I am able to concentrate better for longer than I used to limiting the likelihood of error. And you may think cricket to be one of the more sedate sports but with cardio fitness comes better judgment at the batting crease during a long(ish) innings and more focus at the end of a long, hot day in the field. I am proud of this given that I feel that I can out perform those half my age of similar ability while playing at a good standard.
And when someone says, “gee you cycle all that way to work (20km)? You must be fit…”. Well, it’s all relative. No I am not as fit as others who can go 100km at faster speeds than me and able to function for the rest of the day (I don’t have time for that anyway). Yes, I can ride regularly and do a full days work without being any more tired than usual. I’m fit because I do ride regularly when I would rather lie in a warm bed for another 30 minutes…or look for excuses not to do something that will make me slightly uncomfortable for a short period like the housework for example**. And there’s the “thing”-it has taken me 6 years of riding my bike between 3000-5000 miles a year to improve my fitness that by 24% to an excellent level of fitness. As Jim says, “you can’t get fit by polishing the couch with your butt”. Amen to that…
*they didn’t directly measure my blood lactate but calculated this on the measured level of carbon dioxide exceeding my oxygen intake. This is an estimated measurement rather than an accurate measurement of lactate but still good enough for me.
**I mean really, who would rather do the ironing, 3 loads of washing and clean the floors when you can hop on a bike and go for an adventure?