Zone 2 cardio workouts have gotten a lot of love lately. The second least-intense type of cardio on a scale of 1 to 5, zone 2 involves raising your heart rate only a bit—to 60% or 70% of your max. It puts little stress on the body and therefore doesn’t trigger the kind of cortisol spike (albeit, a temporary one) that more intense workouts can bring. Hence why a lot of women, particularly those in midlife, tend to hang out in this zone, Louisa Nicola, MMed, a New York–based neurophysiologist who studies Alzheimer’s disease in women, tells SELF. But there’s real value in bumping up the effort to zone 5 (or 90% of your max heart rate) every so often, particularly for your brain health, she says.
To be sure, doing any form of movement offers some brain-boosting benefits: It can help stem inflammation, shuttle more blood (and therefore, more oxygen and nutrients) to your brain, and even pump out proteins that support the growth of new brain cells or strengthen their connections. With zone 5 cardio, though, you can magnify several of these effects and channel others that may come only with that extra burst of intensity.
For instance, a 2024 study of older adults suggests brief bouts of zone 5 cardio interspersed with recovery periods can trigger better performance on memory tests and less age-related shrinkage of the brain’s memory center, as compared to low- or medium-intensity exercise. And a 2020 study found that high-intensity interval training (HIIT) (not moderate-intensity continuous training or resistance training) improved older adults’ cognitive flexibility, or ability to quickly switch between mental tasks. Keep reading to learn why incorporating zone 5 cardio in your workout routine may help keep your brain sharp, and how Nicola suggests everyone—particularly women in midlife—do just that.
Why high-intensity cardio especially supports brain health
Jamming out quick bursts of high-key cardio increases your VO₂ max, or the max rate at which your body can use oxygen during exercise; a higher level reflects greater cardiorespiratory fitness. This, coupled with the “sheer shunting of blood to the brain during high-intensity training can benefit brain health,” Nicola says, “as the brain is a highly vascular organ and needs a constant supply of blood flow to function at its peak.” Hence why studies have linked greater cardiorespiratory fitness and higher VO₂ max to better working memory, decision-making, and processing speed, as well as lower risk of dementia.
That’s an especially relevant finding for perimenopausal women, Nicola says. The related drop in estrogen can lead to dips in muscle mass and fitness; if you don’t mitigate these shifts by keeping on top of physical activity, including high-effort cardio, you could then put your brain at greater risk of decline too, she explains.
