What is the Norwegian 4x4 protocol and why is it considered the gold standard for improving VO2 max?
The Norwegian 4x4 protocol involves elevating your heart rate to 90–95% of your maximum for four minutes, followed by four minutes of recovery — repeated four times. It is considered the gold standard for improving VO2 max because VO2 max, alongside strength, is one of the strongest predictors of all-cause mortality, and just 20 minutes of this type of training per week is enough to maintain your levels.
VO2 max begins to decline around age 35, making it one of the most time-sensitive metrics to train. The protocol's structure — four hard intervals interspersed with recovery — is specifically designed to repeatedly push the cardiovascular system into the zone where adaptation happens fastest. It is a protocol with strong clinical grounding, and it fits into a very short weekly time commitment.
The protocol at a glance
This episode also places the Norwegian 4x4 within a broader picture of cardiovascular longevity. Dr. Ben Levine's research found that four hours of exercise per week over two years reversed heart aging by 20 years in sedentary men around age 50 — but the window for that kind of cardiac plasticity closes around age 65. Starting VO2 max training early is not optional. You can explore the full conversation on Listenly's episode page for The Diary Of A CEO.
What is VO2 max?
VO2 max is the maximum rate at which your body can consume oxygen during intense exercise. In this episode, it is described alongside strength as one of the two strongest predictors of all-cause mortality — meaning how long you live and how well you age is closely tied to how high your VO2 max is. It starts declining around age 35 if left untrained.
"Having strong legs is by far the most important tool in your toolbox for the prevention of Alzheimer's disease."
— Steven Bartlett, The Diary Of A CEO with Steven BartlettSee also
What is the danger of being 'active sedentary' and how does prolonged sitting affect health even if you exercise?
A major finding in 2025 from the Cleveland Clinic identified the danger of being 'active sedentary,' defined as people who exercise for 30 to 60 minutes but then remain seated for the rest of the day — sitting more than 10 hours a day raises cardiovascular disease risk even when weekly exercise targets are met.
How much exercise is needed to reduce the risk of cancer through myokine release?
Just 30 minutes a day of aerobic physical activity can downregulate 13 types of cancers, with the most prominent being breast cancer, colon cancer, and prostate cancer.
What are myokines and how do they protect the brain during resistance training?
Myokines are signaling molecules released from muscles during resistance training that cross the blood-brain barrier and benefit the brain. Key myokines include BDNF (brain-derived neurotrophic factor) and interleukin-6, which actively support cognitive function and brain health.