Official guidelines recommend doing muscle-strengthening activities at least two times per week. But only about a quarter of adults meet those requirements.
That's nearly half as many people who have a regular cardio workout, according to the Centers for Disease Control and Prevention.
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"Some people don't know how to resistance train and are worried they might get injured, while others have an injury or condition that doesn't allow them to weight train to a full capacity," says Araceli De Leon, CPT, a certified personal trainer, kinesiologist and spokesperson for the American Council on Exercise.
"In addition, there is a misconception around weight training among some females, who think they might get too bulky or gain too much muscle," she says.
Another common barrier is "gym-timidation," a lack of knowledge about how to use weight-lifting equipment and the intimidation that can come with it. Women, in particular, reported lower comfort using gym facilities, including strength machines and free weights, according to a November 2020 study from Penn State University.
But hey, as long as you're exercising regularly, does skipping out on pumping iron actually matter that much? Is strength training mandatory?
Cardio bunnies, consider this your wake-up call.
Why Doing Cardio Alone Isn't Enough
Let's be clear: We're not knocking a heart-pumping aerobic workout, which is amazing for your health in so many ways. But if you don't also incorporate resistance work, your body will pay the price.
"Your muscles might atrophy — you will lose muscle mass and endurance because you're not using your muscles as much," De Leon says. "Your ligaments and tendons can also weaken."
Skipping out on strengthening is also bad for your bones. "Weight training puts stress on your bones, which nudges bone-forming cells into action," De Leon says. "If you don't do resistance exercises, your bones may get weaker and lose some mineral content."
This is especially important for older adults — primarily those who are postmenopausal, as the decline in estrogen levels leads to bone loss, increasing your risk of fractures.
In fact, resistance exercise alone or in combination with other forms of physical activity is the ideal training for improving bone mass in people who are postmenopausal, middle-aged and older adults, according to a December 2018 review in Endocrinology and Metabolism.
Finally, if weight loss is your goal, you won't torch nearly as many calories without resistance training, says A. Brion Gardner, MD, an orthopedic surgeon specializing in sports medicine at the Centers for Advanced Orthopaedics in Manassas, Virginia.
"When you do a 30-minute cardio session, you are burning calories for that 30 minutes," he says. "But a 30-minute weight-lifting session will have you burning calories for the rest of the day, an effect known as excess post-exercise oxygen consumption."
That's because strength training, by causing microscopic stress to your muscles, triggers your body to enter a recovery state. That muscle recovery uses calories for energy.
Plus, the more lean muscle you have, the more you'll increase your basal metabolic rate, the number of calories you burn each day just to maintain normal biological function. Muscle is metabolically active, meaning it burns more calories at rest than body fat, he says.
The Benefits of Strength Training
Not convinced yet? "There are so many benefits to resistance training, even if you already have an aerobic program," De Leon says. "Because everything in the body is connected, having a solid muscular foundation is important in the way one's body moves, heals and interacts with other body systems."
Just check out all these major payoffs.
You'll Prevent Injury and Promote Healing
Increasing your strength training volume and intensity are associated with a reduced risk in sports injury risks, according to an August 2018 meta-analysis in the British Journal of Sports Medicine.
A 2017 report from the American College of Sports Medicine also shows that following a resistance-training program is associated with a lower incidence of stress fractures, falls and low-back injuries in people who are physically active.
And if you do get hurt? You'll bounce back more quickly and efficiently if you've been sculpting muscles.
"Resistance training strengthens your tendons and ligaments, which can help you recover from injuries, like a sprained ankle or dislocated shoulder," De Leon says. "It will also improve your balance and posture by strengthening the small stabilizers that keep you erect."
It Will Enhance Your Athletic Performance
Runners with a strength-training practice significantly improve their speed and endurance, according to a September 2019 study in the British Journal of Medicine. "Increased muscle fiber size and contractile strength lead to greater physical capacity," De Leon says.
She explains that her own resistance workouts have helped her become stronger in other pursuits. "I'm a long-distance runner, and targeting my leg, core and glute muscles helps me have longer, more successful runs," she says.
Her strength-training routine also allows her to be a more powerful rock climber, stabilizes her in yoga practice and prepares her for snowboarding days.
You May Reduce Your Risk of Disease
A November 2017 study in the Journal of the American Heart Association found that moderate strength training (between 100 to 145 minutes per week) is associated with a lower all-cause mortality risk in older women.
In fact, older adults age 65 and over who followed recommended guidelines to strength train at least twice per week had 46 percent lower odds of all-cause mortality than those who didn't, in a February 2016 study in Preventative Medicine.
But that's not all — research shows that women who focus on strengthening their muscles reduce their risk of type 2 diabetes by 30 percent and cardiovascular disease by 17 percent compared with those who don't strength train, according to a January 2017 study in Medicine & Science in Sports & Exercise.
The bottom line: Combining strength training with aerobic exercise is linked to an even lower risk of type 2 diabetes, cardiovascular disease and early death than doing cardio alone.
It Can Help Boost Your Mood
According to a June 2018 meta-analysis in JAMA Psychiatry, resistance training reduces symptoms of mild to moderate depression.
"Resistance training regulates your blood flow and heart rate, which clears away brain fog and pumps you full of feel-good endorphins," De Leon says.
As you perform new feats of strength, your mental strength and confidence will also improve.
You'll Reduce Low-Back Pain
A small May 2020 study in BMC Sports Science, Medicine and Rehabilitation found that people with lower back pain experienced significantly less discomfort and saw improvements in pain-related disability when they followed a strength-training program. (A randomized clinical trial looking at this effect is currently underway.)
De Leon explains that strengthening your core via resistance work lends support to your lumbar spine (lower back), relieving pressure and pain. Bonus: The study participants also reported an increase in energy levels.
You Might Sleep Better at Night
Building muscle may even improve shuteye, according to a small May 2015 study in the Journal of Strength and Conditioning Research, in which people fell asleep faster and had fewer nighttime awakenings on days when they engaged in resistance training.
Which Kind of Strength Training Is Best?
There are many different ways to strength train, but the best modality for you depends on your abilities, goals and needs. Here's the 101.
"Although both machines and free weights, such as dumbbells and kettlebells, allow you to gain a similar amount of muscle size and strength, free weights require more core engagement and activate more muscle groups than a machine," De Leon says. Without the support of a machine to hold you in the proper position, your body is forced to work harder to maintain your posture.
"As a result, free weights are better for building muscle long term, compared to a machine that may only be targeting specific muscles," De Leon says.
Because machines provide more support, they can be a good bet for beginners who haven't yet honed their form. "A machine is also great to work on improving your form and range of motion after an injury," De Leon says.
"These [resistance bands] are cheap and portable," De Leon says. "Although they do increase muscle size and strength, in the long run, they will become less challenging." To make your strength workouts more challenging with resistance bands, you can add them to your dumbbells or kettlebells.
"Body-weight workouts use your own weight to provide resistance against gravity," De Leon says. The best part is that body-weight exercises don't require any special equipment, like weight machines, dumbbells or even resistance bands. You can do them anytime, anywhere, which is especially helpful if you're avoiding the gym during the COVID-19 pandemic.
"To build muscle using body-weight training, gradually increase the amount of reps or train until failure — for example, by doing squats until you physically can't do any more," De Leon says. "You can also try a 'time under tension' workout, where you perform each movement very slowly so that it becomes more difficult."
So, How Bad Is It Really to Never Strength Train?
As long as you are still getting an aerobic workout, you're not doomed if you skip pumping iron. "There is no harm per se in not weight training," Dr. Gardner says.
But it's certainly not ideal. "Over time, it can lead to adverse health effects and the loss of fitness gains," De Leon says. "People with a strength-training practice have an overall greater quality of life."
Aim to strength train at least twice per week, and experiment with different types of resistance-training equipment to help you figure out what will help you reach your goals. Because the more you enjoy that activity, the higher the chances you'll stick to a routine.
Ultimately, you'll be better off if you quit resisting resistance training. Now drop and give us 20!
- Centers for Disease Control and Prevention: "2008 Physical Activity Guidelines for Americans"
- Journal of the American Heart Association: "Strength Training and All‐Cause, Cardiovascular Disease, and Cancer Mortality in Older Women: A Cohort Study"
- Preventative Medicine: "Is Strength Training Associated With Mortality Benefits? A 15-Year Cohort Study of U.S. Older Adults"
- Medicine & Science in Sports & Exercise: "Strength Training and the Risk of Type 2 Diabetes and Cardiovascular Disease"
- American Journal of Epidemiology: "Does Strength-Promoting Exercise Confer Unique Health Benefits? A Pooled Analysis of Data on 11 Population Cohorts With All-Cause, Cancer, and Cardiovascular Mortality Endpoints"
- JAMA Psychiatry: "Association of Efficacy of Resistance Exercise Training With Depressive Symptoms Meta-Analysis and Meta-Regression Analysis of Randomized Clinical Trials"
- Sports Medicine: "The Effects of Resistance Exercise Training on Anxiety: A Meta-Analysis and Meta-Regression Analysis of Randomized Controlled Trials"
- BMC Sports Science, Medicine and Rehabilitation: "Periodized Resistance Training for Persistent Non-Specific Low Back Pain: A Mixed Methods Feasibility Study"
- Journal of Strength and Conditioning Research: "Effects of Resistance Exercise Timing on Sleep Architecture and Nocturnal Blood Pressure"
- Endocrinology and Metabolism: "Effects of Resistance Exercise on Bone Health"
- British Journal of Medicine: "Infographic. Running Myth: Strength Training Should Be High Repetition Low Load to Improve Running Performance"
- British Journal of Sports Medicine: "Strength Training as Superior, Dose-Dependent and Safe Prevention of Acute and Overuse Sports Injuries: A Systematic Review, Qualitative analysis and Meta-Analysis"
- American College of Sports Medicine: "Resistance Training and Injury Prevention"
- Penn State: "Researchers Study Strength-Training Gender Gap, Possible Solutions"
- Physical Activity Guidelines for Americans