In an article in European Journal of Preventive Cardiology, May 30, 2016, titled “Low aerobic capacity in middle-aged men associated with increased mortality rates during 45 years of of follow-up”,  by Per Ladenvall, Carina U Persson, Zacharias Mandalenakis, Lars Wilhelmsen, Gunnar Grimby, Kurt Svardsudd, and Per-Olof Hansson, they report that in a population of middle-aged men (54 years of age), low aerobic capacity (measured in VO₂ max) is a significant predictor of early death, aside from traditional risk factors like smoking, high blood pressure, and high cholesterol. So what is VO₂ max?

VO₂ max is the maximum rate of oxygen consumption, which can measured during exercise, typically on a treadmill or bicycle. VO₂ max is expressed either as an absolute rate in (for example) liters of oxygen per minute (L/min) or as a relative rate in (for example) milliliters of oxygen per kilogram of body mass per minute (e.g., ml/(kg·min)). What is considered an excellent, good, fair or poor VO₂ max is age and gender dependent, so for a male my age, and excellent value is greater than 41, and a very poor value is less than 22. When I first went to the Canyon Ranch in 2009 my VO₂ max was 16, and when I last had it measured 6 years later, it was 39.76, bordering on excellent. So by just that measure, I have added years to my life.

One of the ways being touted to improve VO₂ max is through High Intensity Interval Training (HIIT), which consists of short, intense workouts, which can vary from 4–30 minutes per day, and which are performed at your absolute physical capacity. While there is evidence to show that HIIT can improve cardiovascular development, which could help improve VO₂ max, my feeling is that it is not a sustainable regime.

From my own experience, to took me 2 years to take off all 230+ lbs., and it has been a challenge to maintain that weight loss the 4 years thereafter. I have been extremely disciplined about exercising at least 1 hour/day for just about every day over that time, and most days, at least 2 hours a day, at a fairly high intensity level, but during that time, I have suffered injuries, been sick, been tired, had travel issues, etc., so on a number of days it was hard enough getting an hour of exercise at a moderate level of exertion.  Forget about trying to sustain a max intensity level just about every day, even if it was for a much shorter period of time. Also, you should expect, with HIIT, that you will get injured more at your peak level of performance, than would be the case with a more moderate exercise regime, which could then lead to setbacks.

So my suggestion to improving VO₂ max, is to utilize a bit more moderate exercise regime, over a longer period of time per day, than a HIIT regime. I think that works best over the long run as it is sustainable.