As I wrote about in my article, “The 5 Aspects of Physical Training,” power is the energy that we use beyond the energy needed for day-to-day movement or even for moderate Zone 2 cardio exercise. In London I live about a third of the way up one hill in one direction and at the bottom of a hill in 2 other directions. Given that I walk fairly quickly, I can feel myself needing this extra energy by the time I get to the top of those steep hills. I am not out of breath, but I can feel the extra effort that is prompted by being slightly above my aerobic threshold, causing my heart to beat faster and increasing my breathing. I know that at this point my body has switched to anaerobic energy. Now, my body is no longer fueled by oxygen but by burning the limited amount of glycogen that I have stored in my muscles.

This kind of energy, whether it is powering up hills, climbing stairs, lifting weights (or luggage), rushing through an airport wearing a heavy backpack, or even sometimes keeping up with my daughters comes at a premium as we get older. It is the “fight or flight” burst of energy we evolved that helps us hunt, fight, or escape danger. It is the ability to accelerate and maintain greater effort than is required for Zone 2 or other activities.

We can measure this “power push” as our VO2 Max, that is, the maximum amount of oxygen we can process. (You will need a stress test to measure this.) VO2 Max declines as we age, but the good news is that we can train for it, increase our VO2 Max, and keep that power for much longer than we’ve been told we can. The key to increasing our VO2 Max is called High Intensity Interval Training (HIIT). And while I have written about this before, here is some new information as well as some important points that bear repeating.

(Note: Before taking on HIIT training, please get a full cardio check-up, including an EKG, stress test, and possibly a heart scan, or whatever your physician recommends.)

What I Do

I usually do 1 HIIT session a week. It doesn’t take very long, but by the end of it I am pretty depleted, even though my endorphins are on overdrive. I usually alternate between 2 totally different kinds of sessions on different weeks. One focuses on shorter bursts and the other is longer, sustained, and more gradual.

The first type of session is 10 to 15 short bursts at an all-out maximum effort for 15 to 30 seconds, followed by a short recovery of about 1½ that time (for example, a 30-second all-out burst gets a 45-second recovery time). I do this HIIT training either on a stationary bike, a Rogue bike, a rowing machine, or a cross-country skiing machine in the gym. (You can also do this on a steep hill or sprinting on a bike outside, if you prefer. There are also many variations like CrossFit workouts. Check them out online and find some that work for you.)

The second variation I do is walking as quickly as I can, powerwalking really, up the aforementioned hills, which takes about a minute. I then gradually walk downhill, which takes about 90 seconds. I repeat this circuit about 10-15 times.

Like Zone 2 workouts, what matters in HIIT is heartrate, but the HIIT heart rate goal is different. (I urge you to wear some sort of heart monitor for both. In particular, tracking your heart rate when doing HIIT training is very helpful.) My maximum heart rate (MHR) is about 160, and my resting heart rate (when I wake up) is between 55 and 60. When I do my HIIT sessions my heart rate goes up to about 155 toward the middle and end of my workout (this is over 95% of my MHR). My heart rate goes down relatively quickly during the “rest” phases, into the 120s. When it doesn’t come down as quickly after 10 or so intervals, I know I’m reaching the point where I should stop. That’s usually 10-15 sets or circuits.

In my reading, the general advice is that, to be effective, HIIT training should take your heart rate to 85% of maximum or above. Ironically, this is about the same percentage of effort our hearts get to when we have sex, which I will leave you to ponder on your own.

Other Benefits

VO2 Max is linked with longevity. Inspirational athletes like Olga Kotelko, the record-setting 90-year-old, had it in abundance. In addition to extra years and extra energy, HIIT training also boosts glycogen storage, creates more efficient mitochondria, promotes stem cell growth, increases Brain-Derived Neurotrophic Factor (BDNF), which is a key protein in brain cell growth and dementia protection, and increases the body and the brain’s ability to burn lactate as fuel.

Other Dimensions

While HIIT is not everyone’s cup of tea, my own practice encourages me to experience power in other dimensions as well. Power is the engine of change. How capable am I of changing gears in my life, making changes when something isn’t working, speeding up, slowing down, or saying no or yes when those aren’t my usual comfortable responses? In my world these emotional aspects are intertwined with the physical ones and can be influenced by training and experience in either one. But that’s a bigger subject to address in another post. For now, remember that HIIT training is a vital part of the 5 aspects of physical training you need for your health, vitality, and longevity.