Podbit · The Diary Of A CEO with Steven Bartlett
The Norwegian 4x4 is four rounds of 4 minutes at 85–95% of maximum heart rate, each separated by a 3-minute recovery. It's one of the most evidence-backed protocols for rebuilding cardiovascular capacity and VO2 max — and it works on a stationary bike as well as a track.
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At 1:02:30 · chapter starts 1:00:18
Asked which exercises people stop doing as they age but should keep, Dr. Estima's answer is immediate: sprinting. VO2 max — the body's oxygen processing capacity — declines 10% per decade without active effort, mirroring the 1% per year muscle decline. The Norwegian 4x4 protocol (four 4-minute intervals at 85–95% max heart rate, with 3-minute rests) is introduced as an evidence-backed solution. A study of women averaging 58 years old found a 10% VO2 max increase in just 8 weeks — and crucially, their mitochondrial efficiency gains were 69%, compared to 49% in 18–30-year-olds. The message is galvanising: ageing widens the gap but also enlarges the upside. It is never too late to start. [1] — Dr. Stephanie Estima "A Norwegian 4x4 sprint protocol study on women averaging 58 years old produced a 10% VO2 max increase in just 8 weeks — and their mitochond…" 1:03:10 [2] — Dr. Stephanie Estima "Older women: 69% mitochondrial efficiency gain vs 49% in young: The same sprint protocol study found postmenopausal women achieved 69% mito…" 1:03:50
Without active training, VO2 max declines by approximately 10% per decade — meaning cardiovascular capacity is something you must actively maintain, not just preserve.
A Norwegian 4x4 sprint protocol study found women with an average age of 58 increased their VO2 max by 10% in just 8 weeks.
A Norwegian 4x4 sprint protocol study on women averaging 58 years old produced a 10% VO2 max increase in just 8 weeks — and their mitochondrial efficiency gains of 69% beat the 49% achieved by 18–30-year-olds. The gap was bigger, but so was the upside.
The same sprint protocol study found postmenopausal women achieved 69% mitochondrial efficiency improvements — outperforming the 49% gains seen in 18–30-year-olds.
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