My Garmin's an unforgiving mistress. Last year, building on some speed drills in the summer, she granted me a max VO2 of 42. This put me well into the "excellent" category for my age. Then, in the fall, I had trouble with stress and sleeping well. This affected my running. I became inconsistent, and my perceived effort on most of my runs was high. After a few months, Garmin had me down to a VO2 max of 38. This was merely good for my age. After January 1, I clawed my way to 39. Garmin continued to judge me as merely "good," a great insult to my ego. "Good" is not good enough. Then, on January 27, Garmin took pity on me and elevated my pedestrian 39 to "excellent."  (As people age, the algorithms readjust the categories because we naturally decline in VO2 max as the years and months go by.) I was mollified.

Despite much inertia and lack of desire to be out in the cold, I did my five miles on Monday. In all fairness, I cannot whine about the winter Maryland weather. But I'm from south of Miami, South Florida, and have never been able to bend my mind to like running in anything much below 50 F. But on Monday, Garmin decided to reward me one more time. After I saved my run data, I scrolled through the day's health status data on my smartwatch. It had granted me another VO2 max point, bringing me to 40. 

Why did my Garmin grant me two points in such a short timeframe? There are two hills in my neighborhood that I have dubbed Mount Duckettown and Mount Tedinitis. The first is 0.4 miles and rises 50 feet. The second is 0.22 miles and rises 48 feet. I quit running them during the fall as cresting them exacted too much of a price, usually leaving my lungs screaming for air. I added them back into my five-mile route in mid-January, and the rewards followed. 

I'm under no illusion about further progress. The price for the next points will not be more base effort runs but with high-speed repetitions. “The process of raising a VO2 max is similar to increasing strength gains in a muscle. A muscle will only gain up to what is demanded of it. It will not get stronger than what is customarily required. The same applies to VO2 max. If a higher demand is placed on the cardiovascular system, then the capacity to tolerate those demands will increase up to a genetic limit.” To run fast, you have to run fast.

Some may wonder why I feel the need to chase VO2 max. I could quote the American Heart Association here: 

Mounting evidence has firmly established that low levels of cardiorespiratory fitness (CRF) are associated with a high risk of cardiovascular disease, all-cause mortality, and mortality rates attributable to various cancers. A growing body of epidemiological and clinical evidence demonstrates not only that CRF is a potentially stronger predictor of mortality than established risk factors such as smoking, hypertension, high cholesterol, and type 2 diabetes mellitus but that the addition of CRF to traditional risk factors significantly improves the reclassification of risk for adverse outcomes.

But, to me, it's just a grade, a bar to surpass. It's a primary indicator of health, athletic performance, and biological age.