Hard workouts pay off for women. (Photo by Unsplash+ in collaboration with Getty Images)

Wearable device data from about 85,000 people suggests striking sex differences that challenge current health guidelines

In A Nutshell

• Women in this study reached similar heart protection with about half the weekly exercise time men needed, based on wearable data from about 85,000 adults.
• Among people already living with heart disease, meeting activity guidelines was linked to a much larger drop in overall death risk for women than for men.
• These findings are associations, not proof of cause and effect. The cohort was mostly white and healthier than average, so results may not apply to everyone.
• If confirmed, simpler, sex-specific targets and “show up most days” messaging could help more people meet goals without spending hours in the gym.

Women may achieve similar heart disease protection as men with about half the weekly exercise time. That’s according to research tracking approximately 85,000 people wearing wrist accelerometers measuring moderate-to-vigorous physical activity for a week.

The study, published in Nature Cardiovascular Research, reports that women reached roughly a 30% lower coronary heart disease risk at about 250 minutes of weekly exercise, while men needed approximately 530 minutes for comparable protection. Among people who already had heart disease, the gap looked even wider: meeting activity guidelines was linked to about 70% lower overall death risk for women versus 19% for men.

Major health organizations currently recommend identical exercise targets for both sexes: at least 150 minutes of moderate-to-vigorous activity per week. Women already struggle more than men to hit these targets, yet this research suggests they may need less time to reap the same rewards.

Exercise And Gender By The Numbers

Researchers from Xiamen University analyzed UK Biobank data spanning nearly eight years. Rather than relying on people’s memories of how much they exercised (which tends to be overly optimistic), participants wore devices that objectively tracked their movement.

But despite doing less, the minutes were linked to larger cardiovascular benefits in women than in men.

Among people without heart disease at the start, women who hit the 150-minute weekly target showed 22% lower risk of developing heart problems during follow-up. Men meeting the same target? Just 17% lower risk.

For those already living with heart disease, the pattern held. Active women had death rates of 1.76% versus 9.15% for inactive women. Active men fared better than inactive men too (9.38% versus 15.13%), but the relative benefit was smaller.

Men have to exercise for about twice as long as women to see the same heart health benefits. (Photo by Ketut Subiyanto from Pexels)

Why Women’s Bodies Might Respond Differently

Scientists don’t have the complete answer yet, but they’ve got some educated guesses.

Estrogen could be key. Women naturally have much higher levels than men, and research shows estrogen boosts fat burning during exercise. Since using fat for fuel (rather than just sugar) appears to benefit heart health, this hormonal difference might partly explain why women see bigger returns on their exercise investment.

Muscle composition offers another clue. Men have more type II muscle fibers, built for quick, powerful movements but dependent on sugar metabolism. Women have more type I fibers, which excel at endurance and efficiently burn fat. These differences in how muscles work during sustained activity might translate to different heart benefits.

The researchers stress these are still theories requiring lab studies to confirm.

Showing Up Matters

The study also looked at consistency. Each extra day women squeezed in about 21 minutes of exercise was linked to 6% lower heart disease risk. For men, each active day is connected to about 4% lower risk.

Women who exercised daily saw their heart disease rates drop from 5.2% to 1.5%. Men who went from zero to seven active days weekly saw rates fall from 10.2% to 4.7%.

If these findings hold up in more diverse populations, they might reshape how we think about exercise recommendations. Right now, telling everyone to hit the same target may discourage women, who globally lag behind men in meeting activity guidelines (33.8% of women versus 28.7% of men fall short).

Knowing that women might achieve similar or better protection with less time could help narrow this gap. And with fitness trackers becoming ubiquitous, personalized targets based on sex, health status, and individual response patterns could become more common rather than one-size-fits-all advice.

The Caveats

The UK Biobank participants were mostly White and healthier than average, so results may not apply to everyone. Some subgroups were small: only 340 highly active women with heart disease provided data, compared to 1,237 men.

The study tracked overall deaths, not just heart-related ones, since there weren’t enough cardiac deaths to analyze separately. And while the data strongly suggests exercise benefits differ by sex, this observational design can’t prove cause and effect the way a controlled experiment could.

The biological mechanisms remain educated guesses. Lab research testing how male and female bodies actually respond to exercise at the cellular level will be needed to explain what’s driving these differences.

But for now, the message seems clear: when it comes to exercise and heart health, equal time doesn’t mean equal benefit.

Disclaimer: This article is for general information and education only. It is not medical advice. Talk with your clinician about what level of activity is safe for you.

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Paper Summary

Methodology

This study examined 85,412 UK Biobank participants who wore wrist accelerometers for one week between 2013 and 2015. Researchers analyzed two groups: 80,243 adults without heart disease (average age 61.5, 57% female) and 5,169 with established heart disease (average age 66.9, 30% female). The devices measured physical activity intensity in 5-second intervals, defining moderate-to-vigorous activity as periods where acceleration exceeded a specific threshold. Researchers tracked participants for a median of nearly 8 years, linking to medical records to identify new heart disease cases and deaths. Statistical models adjusted for numerous factors including age, lifestyle habits, existing health conditions, and genetic risk.

Results

Each 30-minute weekly increase in exercise was associated with lower heart disease risk in both sexes, but women showed stronger effects. Meeting the 150-minute weekly standard linked to 22% risk reduction in women versus 17% in men. To achieve 30% risk reduction, women needed about 250 weekly minutes while men needed 530. Among people with existing heart disease, active women experienced 70% lower all-cause death risk compared to inactive women, while active men showed 19% lower risk than inactive men. Each additional active day (meeting roughly 21 minutes) was associated with 6% lower risk for women and 4% for men. Multiple sensitivity analyses confirmed these sex differences remained consistent across different analytical approaches.

Limitations

The cohort was predominantly white and healthier than the general population, limiting generalizability. Some subgroups had small sample sizes, particularly highly active women with heart disease. The one-week accelerometer measurement may not capture long-term activity patterns. The observational design cannot prove causation despite extensive statistical adjustments. The study examined all-cause mortality rather than heart-specific deaths due to limited events. Proposed biological mechanisms remain speculative without laboratory confirmation.

Funding and Disclosures

National Natural Science Foundation of China (grants 82404379, 82370390), Fujian Provincial Health Technology Project (grant 2024QNB013), and Xiamen Science and Technology Project (multiple grants). Authors declared no competing interests. UK Biobank application number 134551.

Publication Information

Chen J, Wang Y, Zhong Z, Chen X, Zhang L, Jie L, Zhang Y, Wang Y. Sex differences in the association of wearable accelerometer-derived physical activity with coronary heart disease incidence and mortality. Nature Cardiovascular Research. Published online October 27, 2025. doi:10.1038/s44161-025-00732-z

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