21/12/2025
The time we take to exercise is precious! Let’s not waste it 💪
Zone 2 has had a massive moment, but a new narrative review confirms something I’ve been saying for years: Zone 2 is not the magic metabolic solution it’s been sold as.
Yes, Zone 2 (easy, steady, conversational pace) has its place. It’s enjoyable, it’s accessible, and if it gets you moving then great! But the idea that it’s the best way to build mitochondria, burn more fat, or improve metabolic health for the average person? That just doesn’t hold up in the data.
This latest review highlights how most of the Zone 2 hype came from watching elite endurance athletes—athletes who train for HOURS a day and do enormous amounts of Zone 2 work. Of course they have incredible mitochondrial and fat-oxidation capacity. But using that as the model for everyday active women? It just doesn’t translate.
The new review makes this crystal clear: Higher-intensity exercise (above Zone 2) creates bigger, more meaningful improvements in mitochondrial function and cardiometabolic health, especially when your training volume looks like a normal human’s, not a pro athlete’s (think ~5hrs a week, not 15-20+).
This is why I’ve never advocated Zone 2 for women. Yes, it’s one tool. It can absolutely live in your training week. But it’s not THE tool—and it’s certainly not the key driver of the adaptations most women actually need.
If you want stronger mitochondria, better metabolic health, and real performance gains? Use all your gears and don't be afraid to rev your engine and push into higher-intensity zones 1-2 times a week.
You can check out the research for yourself here: https://link.springer.com/article/10.1007/s40279-025-02261-y
