In 2018, the Physical Activity Guidelines for Americans advised adults to do at least 150 to 300 minutes of moderate-intensity exercise like brisk walking, cycling, or dancing—or 75 to 150 minutes of vigorous exercise like running—every week. And they recommended strength exercises at least twice a week.
Newsflash: Most of us aren’t hitting those targets. We’ll find a routine post-pandemic, after the holidays, when work calms down, when the weather is warmer (or cooler). But our bodies aren’t frozen in time while we’re not exercising. We’re paying a price.
Here are eight reasons to get moving today.
1. Exercise may help keep your brain sharp.
Struggling to remember the right word or where you left your keys? Don’t always connect the dots as fast as you used to? While that’s a normal part of aging, exercise may help keep people sharp at any age.
“Physical activity seems to make people a bit more hardy against cognitive decline,” says Charles Hillman, associate director of the Center for Cognitive and Brain Health at Northeastern University.
“And it can lower your risk for more serious cognitive impairments like dementia.” That’s based on studies that tracked thousands of people for up to 12 years.
The good news: You don’t have to wait for decades to reap the benefits.
“One of the most notable findings is that a single bout of exercise has transient benefits on cognitive function,” says Hillman, who served on the expert panel that examined the evidence for the Physical Activity Guidelines.
In one study, 42 middle-aged and older women did light stretching, 30 minutes of brisk walking, or 30 minutes of strength training on separate days. On the days they walked or lifted weights, the women’s reaction times were faster on a test of attention than on the day they stretched.
“Another winner that surprised us was crystallized intelligence,” he adds. “That’s our ability to remember facts: people, places, things like that. We had known that fluid intelligence—the ability to problem solve and think abstractly—gets a boost from exercise, but it turns out that crystallized intelligence benefits as well.”
Which exercise gives your noggin the best boost? “We have the most evidence for aerobic exercise,” says Hillman.
Strength training and lighter-intensity activities like yoga may also help, though there’s less research on those types of exercise.
Exercise protects the brain, at least in part, by changing its physical structure.
“Both gray matter—which are the neurons themselves—and white matter—which improves how well the neurons communicate with each other—benefit from physical activity,” Hillman explains.
In one study, researchers randomly assigned 120 cognitively healthy older adults to do either stretching and toning exercises or 40 minutes of walking three times a week. After a year, the volume of the hippocampus—an area of the brain involved in memory and learning—had increased in the walkers but had declined in the stretchers.
2. Exercise cuts your risk of type 2 diabetes.
“Regular physical activity strongly reduces the risk of developing type 2 diabetes in people of all body sizes,” concluded the Physical Activity Guidelines.
People who hit the Guidelines’ target—150 to 300 minutes a week of moderate-intensity activity—have a 25 to 35 percent lower risk of type 2 diabetes than people who do no activity, said the Guidelines’ expert panel.
One reason: exercise makes your body more sensitive to insulin.
“Insulin tells tissues in the body to take in sugar from the bloodstream,” explains Jenna Gillen, assistant professor of exercise physiology at the University of Toronto. “The more sensitive your tissues are to insulin, the more quickly sugar is removed from blood. Insulin sensitivity is important for lowering the risk of type 2 diabetes.”
And the payoff is immediate.
“Previous studies have shown that a single bout of exercise improves insulin sensitivity for a day or so,” says Gillen. “You don’t have to do months of training before you get an improvement.”
Gillen assigned inactive men to stay inactive or do either 50 minutes of moderate-intensity cycling or 10 minutes of sprint interval training three times a week. (The interval training alternated 20 seconds of fast cycling with two minutes of light pedaling.)
Why test interval training?
“One of the most-cited barriers to exercise participation is a lack of time,” says Gillen. “Sprint interval training or other styles of high-intensity interval training sessions take half as much time as a moderate-intensity session or even less.”
After 12 weeks, both exercise groups had better insulin sensitivity than the men who did no exercise. (The interval and moderate-intensity training were equally effective.) And that was still the case three days after the last exercise session.
But three days could be the limit. One study suggested that after four days of inactivity, “the improvements in insulin sensitivity may disappear,” says Gillen.
So when it comes to boosting insulin sensitivity, she says, “consistency is key. Try not to go more than three days in a row without exercising.”
3. Exercising more (and sitting less) is linked to a lower risk of heart disease.
“We’ve known since the 1950s that physical activity plays an important role in the prevention of heart disease,” says Peter Katzmarzyk, associate executive director of population and public health sciences at the Pennington Biomedical Research Center.
In one recent analysis of nine studies, those who reported doing at least 150 minutes a week of moderate-intensity exercise had a 15 percent lower risk of heart disease than those who did no exercise.
Why? Exercise can lower blood pressure, blood sugar, and other risk factors for heart disease. It also helps keep your blood vessels supple.
How much time you spend sitting—not just how much exercise you do—may also matter.
“The story gets more complicated when you add in sedentary behavior, which also raises the risk for both cardiovascular disease and mortality,” says Katzmarzyk, who served on the expert panel that examined the evidence supporting the Guidelines.
How much sitting is too much?
“More than eight or nine hours a day is where you really start to see an increased risk,” says Katzmarzyk. “And a lot of people greatly exceed that. If you ask, they may say they sit for five or six hours a day. But then you ask about sitting at breakfast, in the car, at work, eating dinner, watching TV, and so on, and it adds up to 12 or 13 hours.”
Katzmarzyk’s advice: “If you have a job where you have to sit for most of the day, you’re going to need a fair amount of exercise to negate the health effects, whereas if you’re up and about most of the day, you don’t need to do as much exercise. It’s a continuum.”
How much is enough to break up the hours in your seat?
“We have trials showing that disrupting your sitting time with physical activity can lower blood sugar levels over the short term,” says Katzmarzyk.
“But we know less about how interrupting sitting time affects other risk factors for heart disease. You’ll hear things like, ‘Get up every hour for 10 minutes.’ That’s not based on any data. Nobody knows what approach actually lowers heart disease risk.”
Katzmarzyk’s bottom line: “Ideally, you should replace some sitting with moderate or vigorous activity. But if all you can do is stand, stand. If you can walk, good. If you can walk briskly, even better.”
4. Exercise can boost your mental health.
If your mental health—and your exercise routine—suffered when the world went into lockdown in March 2020, you weren’t alone.
“Many of us had a decrease in physical activity because we were locked in, and also had a drop in mental health,” says Northeastern University’s Charles Hillman.
In a survey of roughly 3,000 U.S. adults, those who became less active during lockdown reported higher levels of depression, stress, and loneliness, though that kind of study can’t prove whether the drop in activity caused those or other problems.
Still, there’s good evidence that staying active can boost your well-being.
“An acute bout of exercise has immediate benefits for short-term feelings of anxiety,” says Hillman.
For example, researchers had 80 young adults fill out a questionnaire about their current mood before and after resting quietly or biking at a moderate pace for 20 minutes. Feelings of anxiety and tension dropped post-exercise but remained stable in the resters.
“But a commitment to regular exercise really benefits mental health—like anxiety and depression—in the long run,” Hillman points out.
In one study of 10,400 Spanish adults, those who reported more physical activity had a lower risk of being diagnosed with depression, anxiety, or stress after six years.
“Physical activity interventions not only result in lower symptoms of depression and anxiety in the average person,” says Hillman. “They also lower anxiety and depression in people who have a clinical diagnosis of either disorder.”
For example, researchers randomly assigned 72 adults who had been diagnosed with depression to a group that met the aerobic activity goals of the Physical Activity Guidelines, to a group that did about half the exercise recommended by the Guidelines, or to a group that only did light stretching.
After 12 weeks, scores on a depression questionnaire fell by roughly 50 percent in those who hit the Guidelines’ goals, versus 30 percent in both the low-dose exercisers and the stretchers.
5. High levels of physical activity are linked to a lower risk of a number of cancers.
“We’ve known for quite a while that high levels of physical activity are linked with a lower risk of colon cancer and breast cancer,” says Charles Matthews, an epidemiologist at the National Cancer Institute.
But exercise may also keep other cancers at bay.
“High levels of activity are quite consistently linked to a lower risk of endometrial, kidney, bladder, and stomach cancers,” says Matthews. “And there’s emerging evidence that it may also be linked to a lower risk of liver cancer.”
How much is a “high” level of activity?
When Matthews’s team analyzed nine studies on roughly 750,000 adults who were followed for 10 years, those who met the Physical Activity Guidelines had a lower risk for seven types of cancer than those who did no exercise.
“It was one of the first studies to demonstrate that the recommended levels seem to protect against many different cancer types,” says Matthews.
But exercise is linked to a lower risk of some cancers more than others.
“Women who met the recommended levels of activity had a 6 to 10 percent lower risk of developing breast cancer than those who didn’t report any exercise,” Matthews notes.
In contrast, “men and women who met the recommended range had an 18 to 27 percent lower risk of liver cancer.”
“That wide range speaks to how each cancer type can be quite a distinct disease process.”
How might exercise prevent cancer?
“Higher levels of inflammation, insulin, and blood sugar are linked to an increased risk of some cancers,” Matthews explains. And physical activity may help keep a lid on each.
Another possibility: “Physical activity contributes to a lower risk of cancer by preventing long-term weight gain,” says Matthews. Extra weight is linked to a higher risk of many cancers.
6. Not exercising yet? You can build muscle at any age.
“As we age, we all lose muscle,” says Alexander Lucas, an instructor in the department of health behavior and policy at Virginia Commonwealth University.
And we start losing muscle early.
“You’re probably going to peak around age 30,” says Lucas. After age 40, you can expect both your muscle mass and your strength to start to fall, with big drops after age 70 or so.
As we age, that loss of muscle spells trouble.
“As you lose muscle, you’re losing strength, and that will make it harder over time to engage in basic activities,” says Lucas.
“That could be doing things you enjoy, like gardening or dancing, or simple day-to-day things like getting in and out of the shower or going on a walk and feeling confident that you’re not going to fall. Once an older person has a fall, health tends to deteriorate quite quickly.”
What’s more, “gaining fat and losing muscle—both happen with aging—may set you up for a higher risk of problems like insulin insensitivity and type 2 diabetes,” adds Lucas.
“That happens, in part, because your muscles play a major role in removing sugar from the bloodstream.”
As muscle mass drops and fat accumulates between the muscle fibers, the muscle’s ability to remove sugar from the bloodstream is blunted.
Not lifting weights now? Don’t despair. You haven’t missed the window of opportunity to build your strength.
“There is no age at which you cannot build muscle,” says Lucas.
To his point, researchers supervised nine frail adults in their 90s in a challenging strength-training program three times a week. At the study’s start, the participants could lift roughly 18 pounds with one leg in a knee extension exercise. After eight weeks of pumping iron, they could lift roughly 45 pounds.
And you don’t need a gym.
“Walking up and down stairs is great because you’re not moving across level ground,” Lucas notes. “You’re moving your body up against gravity, which builds strength.”
“You can do body-weight exercises like squats, pushups, crunches, or lunges,” he adds. “You can also get some elastic bands or light hand weights and use furniture in your house as tools to build muscle.”
The key: “You have to overload the muscle,” says Lucas. “Make it work harder than it’s accustomed to. That’s how you’ll make the fibers both bigger and stronger.”
7. Struggling to get some sleep? Don’t just sit there.
In one study of roughly 75,000 postmenopausal women, those who were sedentary for more than 11 hours a day were roughly 60 percent more likely to report symptoms of insomnia like trouble falling asleep, waking up during the night, and waking earlier than planned than those who were sedentary for no more than six hours a day.
“Exercise leads to more sleep, better sleep, and it reduces the number of times that people wake up during the night,” explains Northeastern University’s Charles Hillman.
And there’s no wait: Go on a hike or bike ride today, and you’ll likely sleep a bit more soundly tonight.
“The sleep benefits of being a regular exerciser are even greater,” says Hillman.
For example, scientists randomly assigned 437 postmenopausal women with overweight or obesity to do no exercise or to do 15, 30, or 45 minutes of moderate-intensity exercise on most days of the week.
After six months, all three exercise groups reported sleeping better. And the more exercise they did, the more their sleep improved.
More good news: “People believe that if they exercise at night, they won’t be able to go to sleep,” says Hillman. “But that’s not supported by the data. The time of day that you exercise doesn’t necessarily matter.”
8. Even small amounts of physical activity are linked to living longer.
“The World Health Organization says that physical inactivity is the fourth leading cause of death around the world,” says Pennington’s Peter Katzmarzyk.
“The good news is that you don’t have to get to that threshold of 150 minutes of activity per week. Any amount of activity is beneficial.”
When researchers ask people about their exercise habits, then track them for years, the risk for early death plummets in those who do even small amounts of moderate-to-vigorous activity compared to those who are inactive.
“If you’re doing 70 minutes a week—that’s just 10 minutes a day—it’s not as though you’re failing,” says Katzmarzyk. “You’re actually getting a lot of benefit.”
Still, he points out, “the sweet spot is 150 to 300 minutes of exercise per week. That’s where people have the lowest risk of dying early.”
Prefer to track your steps instead of your time?
“Many people wear fitness trackers or look at their step counts on their phone,” says Matthews.
His team looked at data from roughly 4,800 middle-aged and older adults who wore step counters for up to a week and were followed for roughly 10 years.
“Across the board—men and women, younger and older adults, people from different ethnicities—higher step counts were associated with a lower risk of dying.”
In fact, people who took 8,000 steps per day were half as likely to die as those who took 4,000. And super steppers—they took at least 12,000 steps per day—had a 65 percent lower risk of dying during the 10 years of the study.
While it’s always possible that it wasn’t the steps, but something else about the high-steppers, that helped them live longer, why take a chance?
“If you’re wearing a fitness tracker and you’re routinely getting less than 4,000 steps per day,” says Matthews, “you may get substantial benefits by doubling or tripling that amount.”