VO2 max is the best single predictor of how long you will live. Here is how to improve it

The metric that Peter Attia calls the most important number in longevity

VO2 max is the maximum volume of oxygen the body can use per minute per kilogram of body weight. It is expressed in mL/kg/min. An average untrained 50-year-old man has a VO2 max of approximately 35 mL/kg/min. An elite endurance athlete the same age might have 60 or above. A sedentary 50-year-old on the lower end might be at 25.

The 2018 JAMA Network Open study by Kyle Mandsager and colleagues analyzed 122,000 patients who underwent exercise stress testing at the Cleveland Clinic. The association between VO2 max and survival was steep, linear, and larger than any other risk factor studied. Going from low fitness to moderate fitness cut mortality risk by 50 percent. Going from elite to superior fitness cut it further. The mortality benefit of high cardiorespiratory fitness was greater than having no hypertension, no diabetes, and not smoking.

How to train it

Zone 2 training (foundation). Zone 2 is moderate aerobic exercise at an intensity where conversation is possible but effortful. Approximately 60 to 70 percent of maximum heart rate. Four to five 45-minute Zone 2 sessions per week over 12 weeks produce measurable VO2 max improvement through mitochondrial biogenesis and cardiac stroke volume improvement. This is the aerobic base that makes high-intensity work more effective and is covered in detail in the Zone 2 article in this library.

Norwegian 4×4 intervals (the most evidence-supported HIIT protocol). Developed at the Norwegian University of Science and Technology by Jan Helgerud and colleagues, the 4×4 protocol produces the largest VO2 max gains per training hour of any validated protocol: four minutes at 90 to 95 percent of maximum heart rate, followed by a three-minute active recovery, repeated four times. Twice per week on top of a Zone 2 base. Multiple RCTs show 10 to 15 percent VO2 max improvement over 10 to 12 weeks.

Measuring maximum heart rate accurately. The 220-minus-age formula is convenient and wrong for many people. The most accurate field test without a lab: three-minute all-out effort on a bike or run followed by immediate heart rate capture. The highest heart rate achieved in this test is close to true maximum. The 4×4 target (90 to 95 percent) is then calculated from this actual maximum rather than the formula estimate.

The Livium recipe

Tool. A heart rate monitor with chest strap for accurate heart rate capture during intervals. The Wahoo TRACKR is the most accurate consumer chest-strap option and pairs with any fitness app. Wrist-based optical heart rate monitors are insufficiently accurate during high-intensity intervals where they matter most, because of the movement artifact and the delay in optical reading. Modern smartwatch estimated VO2 max (from Garmin, Apple Watch, Polar) is an acceptable proxy for tracking improvement over time but is not equivalent to laboratory measurement.

Behavior. A twelve-week protocol: four to five Zone 2 sessions per week (45 to 60 minutes each) plus two Norwegian 4×4 sessions per week, on non-consecutive days from Zone 2. Total training volume is eight to ten hours per week at first inclusion of intervals, building from an initial five to six hours of Zone 2 only. The interval sessions are short (28 minutes total including warm-up and cool-down) and produce disproportionate VO2 max return per training minute.

Threshold. Smartwatch-estimated VO2 max should increase by five to ten units over twelve weeks of this protocol. Subjective markers: Zone 2 pace increases at the same heart rate (a sign of improved aerobic efficiency), the interval sessions feel less catastrophic by week six, and resting heart rate should trend downward as cardiac output improves.

The metabolic support layer

A Garmin HRM chest strap adds running dynamics (vertical oscillation, ground contact time, stride length) to heart rate data, providing biomechanical feedback that supports improvements in running economy alongside VO2 max training. Life Extension Mitochondrial Energy Optimizer supports the mitochondrial biogenesis driven by Zone 2 and interval training, providing the substrates (PQQ, acetyl-L-carnitine, R-lipoic acid) that mitochondrial multiplication requires. NOW Foods D-Ribose 750 mg supports ATP resynthesis during recovery periods from high-intensity training, reducing the perceived effort of subsequent intervals and promoting faster full recovery between interval sessions.

VO2 max targets by age and sex

All values in mL/kg/min. Source: Livium editorial synthesis based on American Heart Association Fitness resources and Kaminsky et al., ACSM’s Guidelines for Exercise Testing, 2022.

Plan of action

• Get a baseline VO2 max estimate from a smartwatch or from the Rockport Walk Test (a validated submaximal field test available free online). Know where the starting point is before designing the training protocol.
• Start with Zone 2 only for four weeks before adding intervals if currently sedentary. Jumping directly into Norwegian 4×4 without an aerobic base increases injury risk and reduces the training adaptation from the intervals.
• Add two interval sessions per week in weeks five through twelve. Use a chest strap heart rate monitor. Hit the 90-95 percent target across all four intervals. If the target is not being hit by intervals three and four, the work-rest ratio needs adjustment.
• Retest VO2 max at week twelve. A five to ten unit improvement is a realistic and clinically significant target. Anything above 50 mL/kg/min in a 50-year-old puts them in the longevity-protective range across all major prospective studies.