Women need to exercise only half as much as men to reap the same longevity benefits, according to a new study published in the Journal of the American College of Cardiology.

That’s good news for women who struggle to motivate themselves to hit the gym, says study co-author Dr. Martha Gulati, director of preventive cardiology at Cedars-Sinai in Los Angeles. “For me, the news to women is: a little goes a long way,” Gulati says.

In the study, men who got about 300 minutes of aerobic exercise every week had an 18% lower risk of dying compared to inactive men, the researchers found. But among women, it took only 140 minutes of weekly exercise to see an equivalent benefit—and the risk of death was 24% lower among those who got about 300 minutes of movement per week. (For both sexes, longevity benefits seemed to plateau beyond 300 minutes of weekly exercise.)

The researchers ran a similar analysis on muscle-strengthening exercise, such as weight training. They found the same pattern: for women, a single weekly strength-training session was associated with just as much longevity benefit as three weekly workouts for men.

Women tend to have less muscle mass than men, Gulati explains, so “if they do the same amount of strengthening exercises, they may have greater benefits with smaller doses just based on the fact that they don’t have as much to begin with.” Other sex-based physiological differences, like differences in the lungs and cardiopulmonary system, may also come into play.

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To reach their findings, Gulati and her colleagues analyzed self-reported exercise habits from more than 400,000 U.S. adults who took the National Health Interview Survey from 1997 to 2017, then compared those data with death records. About 40,000 of the participants died during the study period.

That observational approach—meaning the researchers looked for patterns in preexisting data—can’t prove cause and effect. It’s possible that exercise didn’t cause people to live longer, but rather that active people in the study were healthier overall or had other lifestyle habits that boosted longevity. The researchers tried to control for those possibilities by excluding people who had serious preexisting conditions or mobility constraints, or who died in the first two years of study follow-up, and thus may have been unhealthy from the beginning.

The study was also limited by its reliance on self-reported exercise data, which isn’t always accurate. The survey also asked about exercise people did in their free time, and thus may not have accounted for physical activity that occurred at work or during household chores—a type of movement that research increasingly suggests can meaningfully improve health.

In part because of those limitations, Gulati says more research is required to confirm the findings. But, she says, the study—and others that have reached similar conclusions—offers a clear signal that “women are not just small men” and that sex-based differences must be incorporated into research and public-health policy. “For years, we’ve used men as the standard,” Gulati says, even when it may not have been accurate to do so.

Take the federal guidelines for physical activity, which issue the same blanket recommendation for U.S. adults: at least 150 minutes of moderate aerobic exercise (or 75 minutes of vigorous cardio) and two muscle-strengthening sessions each week. In 2020, about 28% of U.S. men hit both benchmarks, compared to 20% of U.S. women, data show.

Gulati’s research, at least, suggests women may see significant longevity benefits even if they don’t quite meet those targets. But she says the study shouldn’t be discouraging for men, either.
The latest research suggests people of both sexes benefit from even very short chunks of activity, as just a few minutes of movement per day can boost longevity.

“Our pitch should be the same to men and women: something is better than nothing,” Gulati says. “Sit less and move more.”