1: Recommendations around exercise are often “very specific (e.g., how to train for your first marathon) or overly vague (e.g., ‘Just keep moving!’),” Dr. Peter Attia writes in his powerful book Outlive: The Science and Art of Longevity.
“Or they emphasize “cardio” over “weights,” or vice versa,” he notes.
Peter believes there is a better way. He sees exercise through the lens of longevity: How can we utilize exercise to “delay the onset of chronic disease and death, while simultaneously maintaining healthspan for as long as possible?”
He believes there are three dimensions we want to optimize: Aerobic endurance and efficiency (cardio), strength, and stability. All three play an important role in maintaining our health and strength as we age.
Peter believes we should focus on two different aspects of cardio: Maximum aerobic effort (measured by VO2 max), which we’ve covered in prior RiseWithDrews [here and here], and endurance, where we will begin our focus this week.
So, what exactly does it mean to be aerobically fit? Scientifically, it is how efficiently our bodies can deliver oxygen to our muscles and how efficiently our muscles can extract that oxygen, allowing us to run, walk, cycle, or swim long distances.
This ability also impacts our daily lives and our physical stamina. “The more aerobically fit we are, the more energy we will have for whatever we enjoy doing,” Peter writes, “even if our favorite activity is shopping.”
What’s the one word that Peter hasn’t mentioned? Calories.
“Most people think that one of the primary benefits of exercise, if not the primary benefit, is that it ‘burns calories,'” he notes. “And it does, but we are more interested in a finer distinction—not calories, but fuels. . . Aerobic exercise, done in a very specific way, improves our ability to utilize glucose and especially fat as fuel.”
The fitter we are, “the greater our ability to utilize fat, which is by far the body’s most efficient and abundant fuel source,” Peter writes.
We develop this capability through steady endurance work. Which physiologists call “Zone 2” exercise. Athletic trainers categorize physical intensity according to five zones. Zone 1 is walking. Zone 5 is a total sprint.
“Zone 2 is more or less the same in all training models,” Peter explains, “going at a speed slow enough that one can still maintain a conversation but fast enough that the conversation might be a little strained. It translates to aerobic activity at a pace somewhere between easy and moderate.”
2: Peter’s recommendations for Zone 2 training have been influenced by the scientist Iñigo San Millán, who works with elite athletes, including hundreds of top professional cyclists like Tadej Pogačar, the 2020 and 2021 Tour de France champion.
Iñigo’s real passion, however, is studying the relationship between exercise and diseases such as cancer and type 2 diabetes. Peter writes: “He hopes to use his insights into the fittest people on the planet, professional cyclists and other elite endurance athletes, in order to help the very least fit people—the one-third to one-half of the populations with metabolic diseases.”
Iñigo and his colleague George Brooks conducted a study that compared three groups of subjects: “Professional cyclists, moderately active healthy males, and sedentary men. . . They had each group ride a stationary bicycle at a given level of intensity relative to their fitness (about 80 percent of their maximum heart rate), while the scientists analyzed the amount of oxygen they consumed. . . and what primary fuels they were using.”
There was a significant difference: “The professional cyclists could zoom along, producing a huge amount of power while still burning primarily fat,” Peter notes. The sedentary men “relied almost entirely on glucose for their fuel source, even from the first pedal stroke. They had virtually zero ability to tap into their fat stores. . .
“It seems unjust, but the people who most need to burn their fat, the people with the most of it, are unable to unlock virtually any of that fat to use as energy, while the lean, well-trained professional athletes are able to do so easily.”
The study suggests that sedentary individuals should train just like the Tour de France–-bound cyclists, who spend 80 percent of their training in Zone 2. Doing so builds the foundation for their more intense training.
It also helps us build a base of endurance for everything we want to do, “whether that is riding our bikes in a one-hundred-mile century ride or playing with our kids or grandkids,” Peter observes.
3: One of the most significant hallmarks of aging is a decline in aerobic fitness. However, we counteract the natural phenomenon when we exercise consistently in zone 2.
“This, in turn, explains why exercise, especially in zone 2, can be so effective in managing both type 1 and type 2 diabetes,” Peter writes. “It enables the body to essentially bypass insulin resistance in the muscles to draw down blood glucose levels.
“I have one patient with type 1 diabetes,” he continues, “meaning he produces zero insulin, who keeps his glucose in check almost entirely by walking briskly for six to ten miles every day, and sometimes more. As he walks, his muscle cells are vacuuming glucose out of his bloodstream via NIMGU. He still needs to inject himself with insulin, but only a tiny fraction of the amount that he would otherwise require.”
Another giant benefit of zone 2 exercise is that it is very easy to do, even for those currently living sedentary lives.
“For some people, a brisk walk might get them into zone 2,” Peter observes. “There are many different ways to do it: we can ride a stationary bicycle at the gym, or walk or jog or run around the track at the local high school, or swim some laps in the pool.
“The key is to find an activity that fits into our lifestyles, that we enjoy doing, and that enables us to work at a steady pace that meets the zone 2 test: We’re able to talk in full sentences, but just barely.”
Because we are not pushing ourselves to the max, we can listen to podcasts or audiobooks, or just think through issues on our minds. Zone 2 also improves our cognition by increasing blood flow to the brain.
“This is another reason why zone 2 is such an important part of our Alzheimer’s disease prevention program,” Peter suggests. “I think of zone 2 as akin to building a foundation for a house. Most people will never see it, but it is nevertheless important work that helps support virtually everything else we do, in our exercise regimen and in our lives.”
How much time should we spend in zone 2?
We can start small, but ideally, Peter recommends three hours per week or more. “I am so persuaded of the benefits of zone 2 that it has become a cornerstone of my training plan. Four times a week, I will spend about an hour riding my stationary bike at my zone 2 threshold.”
More tomorrow.
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Reflection: How might incorporating Zone 2 exercise into my daily routine impact my overall health and longevity, and what creative ways can I find to make it enjoyable and sustainable for myself?
Action: Schedule at least one Zone 2 exercise session this week, choosing an activity I enjoy and can easily integrate into my lifestyle, such as brisk walking, cycling, or swimming.
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