In 2016, I wrote a column with the rather flippant title: “Yes, Professional Runners Are Weak.” In my defense, I was simply paraphrasing recently retired marathoner Ryan Hall. After hanging up his running shoes, the American half-marathon record holder had worked out hard in the weight room and transformed himself from a scrawny endurance athlete into a big, muscular hunk. “I’ve been small and weak my whole life,” Hall said in an interview with The world of runners“I always wondered what it would be like to be big and strong.”
For Hall, getting muscular has also been a boon to his overall vitality. As he told CNN in 2021, his energy levels are “10 times better” now that he spends “60 to 90 minutes a day” lifting weights, compared to when he was running 130 miles a week. Who can’t relate?
Ryan Hall may be a physical outlier, but his example speaks to one of the most enduring debates in popular fitness culture: Is it better to prioritize cardio or strength training? (With apologies to gym taxonomists, in this article, “strength training” will be used interchangeably with “resistance training.” While strength training is generally aimed more specifically at gaining muscle mass, both forms of exercise involve working the muscles with some sort of counterforce, such as dumbbells or one’s own body weight.)
Even though the pendulum is still swinging back and forth, resistance training seems to be gaining momentum over cardio, at least among some fitness influencers. Runner-turned-weightlifting evangelist Casey Johnston’s popular newsletter “She’s a Beast” describes itself as “counter-programming for the age of thinness.”
At the same time, even accounts that explicitly promote weight loss and fat reduction push back against the idea that aerobic exercise is too important. “What if I told you that by doing less cardio, you could lose more fat?” asks Katie Neeson, an online fitness coach and trainer who runs the TikTok account @thefitmamalife. “The main reason why doing less cardio is going to be great is that you can spend more time working out.”
A common refrain among those advocating for more of us to get involved in strength training is that resistance training will “improve body composition,” a euphemism for “make you sexier.” It’s a reminder that often, the cardio vs. strength training debate is as much about aesthetics as anything else. Indeed, if you have specific fitness goals—whether they’re achieving a certain physique or running your fastest marathon—you should have a clear idea of which form of exercise you should prioritize.
But what about when we consider the issue from a general health perspective?
What is healthier: cardio or strength training?
Professor Duck-Chul Lee is the director of the University of Pittsburgh’s Center for Physical Activity and Weight Management and the author of numerous articles on exercise and long-term health. Earlier this year, he co-authored a study comparing how different types of exercise help reduce cardiovascular disease (CVD) risk factors. The study, published in the European Heart JournalThe study involved 406 adults (53% women) aged 35 to 70, all of whom were overweight or had high blood pressure. Participants were divided into groups who did one of the following activities three times a week for a year: one hour of resistance training; one hour of aerobic training; 30 minutes of resistance training And 30 minutes of aerobic exercise; or no exercise at all. After one year, only the groups that did only aerobic exercise or aerobic exercise and resistance training showed an improvement in their composite CVD risk profile, compared with the no-exercise group.
However, while the cardiovascular disease benefits were nearly identical for those who focused exclusively on aerobic exercise and those who combined it with resistance training, the latter group also showed additional improvements in metrics such as lean body mass. “The message I wanted to get out of this study was that if people replace half of their cardio with resistance training, they get the same benefits in terms of reducing cardiovascular disease risk factors, but they get additional benefits like increased strength and muscle mass,” Lee says.
This isn’t the first time Lee has published a study suggesting that many of running’s benefits can be achieved from relatively low doses. A 2014 study in the Journal of the American College of Cardiology (JACC), which studied the relationship between running and all-cause and cardiovascular mortality in more than 55,000 adults, found that running as little as five to 10 minutes a day at a slow pace had similar benefits to running more than three hours a week.
“The runners were not happy with those results,” Lee told me, noting that he received a fair amount of hate mail from hardcore endurance athletes who felt their fanaticism was being tested. But Lee says the contentious issue of whether it’s possible to do too much the cardio is still undecided.
What about overzealous weightlifters? A widely cited 2022 study by Japanese sports science professor Haruki Momma found that resistance training did reduce the risk of all-cause mortality, but the maximum benefits appeared to cap at 30 to 60 minutes per week. The study cautioned that more research is needed to determine the potential benefits (or harms) of high-volume strength training. To that end, Lee told me he just received a grant to conduct a yearlong study to compare the effects of a weekly weightlifting program of varying intensity levels—from zero to 120 minutes per week.
The difference between benefits for men and women
Not surprisingly, more research is also needed to assess the relative benefits of exercise for men and women. That’s according to another JACC paper published this year, “Sex Differences in Association of Physical Activity With All-Cause and Cardiovascular Mortality.” The study’s authors examined the relationship between the exercise habits of 412,413 Americans (55% of whom were women) and all-cause and cardiovascular mortality from 1997 to 2019. Looking at data from nearly 40,000 deaths during that time period, the study authors found that men experienced the greatest mortality benefit (an 18% reduction in the risk of all-cause mortality) from engaging in 300 minutes per week of moderate-to-vigorous physical activity (MVPA). Women, in particular, experienced a similar benefit from engaging in just 140 minutes per week of MVPA.
Gender differences are also significant in the specific benefits of muscle-strengthening exercises. Among those who regularly engaged in muscle-strengthening activities, men showed an 11% reduction in cardiovascular risk, while in women the risk reduction was as high as 30%.
The study does have its caveats (as with most large-scale fitness studies, all exercise behaviors were self-reported), but the central point that gender differences should probably be taken into account more when developing general exercise recommendations seems hard to dispute. As Susan Cheng, a professor of cardiology at Cedars-Sinai Medical Center and one of the study’s lead authors, told me, “A certain person, with a certain physique, might get much more benefit from 75 minutes of exercise than someone with a completely different physique and body size, who might need 350 minutes to get the same benefit.”
Another co-author of the study, Professor Martha Gulati, who is among other things president of the American Society for Preventive Cardiology, told me that “every time I see “When I talk about recommendations for men and women, my usual question is, ‘Where does that come from?’ Because chances are the data are not robust.”
Bottom line: How much cardio and strength training do you need?
Still, although more studies are needed to refine gender-specific recommendations, current data suggest that most people, regardless of gender, would benefit from following the American Heart Association’s recommendation of 150 minutes per week of moderate-intensity aerobic activity, combined with at least two days per week of moderate- to vigorous-intensity muscle-strengthening activity.
If that sounds a bit ambitious, everyone I spoke to was adamant about the difference between doing a small amount of exercise—as little as five to ten minutes a day—and doing Nothing was much more significant than the gaps in health gains between people at the other end of the spectrum.