Peter Attia MD201 - Deep dive back into Zone 2 Training | Iñigo San-Millán, Ph.D. & Peter Attia, M.D.
At a glance
WHAT IT’S REALLY ABOUT
Zone 2 Physiology, Lactate, Mitochondria and Practical Training Guidance Explained
- San-Millán describes using lactate-versus-power testing and metabolomics to identify Tadej Pogačar's potential and to inform race tactics at the Tour de France.
- The two define Zone 2 as the intensity of maximal mitochondrial stress and fat oxidation, and compare indirect calorimetry, lactate, heart rate and perceived exertion as ways to find it.
- San-Millán explains that blood lactate reflects the balance of production and mitochondrial clearance, so the same value means different things in elite athletes and people with metabolic syndrome, and that diet such as ketosis can distort calorimetry readings.
- For practical training, San-Millán recommends about three to five sessions per week of roughly an hour to an hour and a half, adding short high-intensity efforts after Zone 2, and points to older athletes as proof that compounding gains are possible.
- Their discussion extends to ICU metabolism, metformin, NAD precursors, cancer, long COVID and sedentary muscle, all framed around mitochondrial dysfunction as a common thread.
IDEAS WORTH REMEMBERING
5 ideasLactate at a given power predicts cycling performance.
San-Millán says Pogačar stood out at 19 because his blood lactate was extremely low at a given power output, and that this kind of testing predicts which riders will be strong at the start of a season.
Blood lactate is a net of production and clearance.
San-Millán says elite athletes oxidize lactate inside muscle through MCT1 and mitochondria, so two millimoles in the blood of an elite athlete can reflect greater metabolic stress than in someone with metabolic syndrome.
Simple surrogates work for finding Zone 2.
Both agree that being able to talk but with some strain is a reliable marker, and that 70 to 80 percent of true maximum heart rate is a starting range to be refined with perceived exertion.
Frequency and steadiness matter more than single long sessions.
San-Millán suggests about four days a week of one hour to an hour and a half, compares exercise to a medication dose, and notes that oscillating between zones does not count as true Zone 2 time.
Put high intensity after Zone 2, not before.
San-Millán says finishing a session with a hard interval stimulates the glycolytic system without blunting Zone 2 benefits, whereas hard efforts first raise lactate, which inhibits lipolysis and fat transport.
WORDS WORTH SAVING
5 quotesI always tell people, "If you can exercise, whatever the exercise you do, and maintain a conversation like you and I are doing, you're way too easy. You're probably in zone one."
— Iñigo San-Millán
I wish that we could have a medication, a pill that you could take it and increase the mitochondrial function 'cause it would increase, uh, metabolic health and longevity. But the only medication that we know is exercise
— Iñigo San-Millán
I think that more and more, and this is why you see in so many fields in medicine nowadays, right? That everybody's stumbling upon mitochondria
— Iñigo San-Millán
It's day in and day out, day in and day out, small compounded gains over years, and years, and years is why a 40-year-old overweight smoker can become a world champion at 80.
— Peter Attia
the more convinced I am that if you're gonna rank order things, if you were forced to rank order things, there's nothing that ranks above exercise as the single most potent tool or agent we have to impact longevity.
— Peter Attia
High quality AI-generated summary created from speaker-labeled transcript.
