I’ve always been unwilling to be pressed into bench-pressing. Lifting weights seemed the province of serious athletes looking to improve performance or men looking to bulk up. Instead I walk several miles every day and do yoga regularly. But although research into resistance and strength training is still catching up to that on aerobic exercise, there’s growing evidence that muscle-strengthening routines confer a host of physical and cognitive advantages, some of which can’t be achieved through aerobic workouts alone.
We do not just need to get our steps in; we need to get in reps—as in curls, push-ups and squats. That’s why the federal Physical Activity Guidelines for Americans, the World Health Organization, and others specify two or more sessions a week of muscle-strengthening activities. They mean weight-bearing exercises of moderate or greater intensity involving all major muscle groups. That’s in addition to 150 to 300 minutes of moderate to vigorous aerobic activity. Yet at least three quarters of Americans fail to hit both the aerobic and the strength targets, and the latter is especially rarely met.
All exercise is a form of physical stress. Done correctly, it creates better fitness by making the body adapt to that stress and become stronger. Like aerobic exercise, resistance training increases heart rate and makes the lungs work more to keep the additional blood flow filled with oxygen. But the primary benefit of muscle-strengthening activity comes from the way it taxes the muscles. Pushing or pulling against resistance generates microscopic tears in muscle tissue. These tiny tears are not really damaging: they prompt the muscle to repair itself and build more fibers to become stronger. “You’re trying to hurt yourself for an adaptive benefit,” says epidemiologist and exercise scientist Jessica Gorzelitz of the University of Iowa.
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In 2022 an analysis of several studies found that muscle-strengthening exercises were associated with a 10 to 17 percent lower risk of all-cause mortality than in people who didn’t do such exercises. And the same year, Gorzelitz and her colleagues used data on nearly 100,000 older Americans to show that those who did both aerobic and resistance training had the lowest mortality risk in the entire group. Weightlifting, by itself, also reduced the risk of death from all causes as well as from cardiovascular disease specifically.
These activities don’t just keep us alive—they keep us healthier while we are living. We lose 3 to 8 percent of our muscle mass every decade after the age of 30 and more after age 60. But muscle strengthening allows us to push back against the aging process and build lean body mass. This fosters metabolic health and keeps us lifting our own suitcases and carrying our own groceries. Resistance training also builds better bones—muscles pull on bones, and in response, bones add new cells and get stronger, increasing bone mineral density, which is especially important for women as they age.
In cancer survivors, studies show that muscle-strengthening exercises improved cancer-related fatigue and health-related quality of life. Resistance training also helps to prevent and control diabetes, in part by improving blood glucose storage and circulation. And studies have found that strength training is associated with reductions in anxiety and depression.
Some of the resistance to resistance training is because, compared with aerobic exercise, it’s more complex. With aerobic activities, a step is a step, whether you walk, jog, run or hike, and those steps are easily tracked. But muscle-strengthening exercises include far more variables, says physiologist William Kraemer of the Ohio State University. People need to choose which parts of the body to work and in what order, which equipment to use, what intensity to work at, and how often to rest. For instance, it’s often wise to work large muscle groups before smaller ones, and it’s critical to allow sufficient rest between workouts. Kraemer says those rest periods allow the all-important repair process to begin.
Any form of resistance training will do—pulling on strong elastic bands, push-ups, free weights or weight machines—so long as it puts strain on your muscles. Experts advise that people start small so as not to get hurt. With weights, “you don’t have to immediately jump to hang cleans and deadlifts,” Gorzelitz says.
And aim for the recommended minimum of two sessions per week, although for some people more frequent, shorter sessions might be more sustainable. “You want it to become a habit,” points out Anne Brady, who is a clinical exercise physiologist at the University of North Carolina Greensboro and who coaches private clients online.
Brady advises people who find the gym intimidating or too expensive to get a set of weights or elastic resistance bands for use at home. Professional advice from a trainer is useful, especially at the beginning, she says, but free online videos are “a great starting point.” If you go online, look for presenters with certifications from the American College of Sports Medicine or who are recommended by reputable organizations such as AARP.
It’s important to increase weight and intensity over time, a concept known as progressive resistance. Completing three sets with a five-pound dumbbell is challenging for a beginner but provides little benefit to a gym regular. “If you keep doing the same thing over and over again, no adaptations occur,” Kraemer says.
That’s a message to take to heart—and to the rest of our bodies. Most of us could strengthen our health by adding strength training to our routines.
This is an opinion and analysis article, and the views expressed by the author or authors are not necessarily those of Scientific American.