What lifting weights does to your body—and your mind

When it comes to fitness guidance, many of us hear familiar refrains about the benefits of cardio exercise. Calls for cycling, running, jogging, walking, or simply "getting your steps in" are commonplace while recommendations to spend more time lifting weights or doing push-ups are scant.  

Though aerobic exercise is critical for optimal health, it’s also important to prioritize resistance training—a form of strength training that utilizes resistance from weights, bodyweight, or resistance bands, to strengthen muscles. Doing so brings about many proven and often surprising health gains. These include boosting longevity, reducing anxiety and depression, strengthening balance and flexibility, helping with weight management, decreasing risk of personal injury, improving blood pressure and cholesterol levels, and significantly boosting heart health.

“A properly designed resistance training program can improve mobility, physical functioning, performance in activities of daily living, and improve athletic performance as well as preserve the independence of older adults,” says Michael Fredericson, a physician and the director of physical medicine and rehabilitation sports medicine at Stanford School of Medicine.

Despite such benefits, some people dismiss resistance training as being only for bodybuilders or gym goers—a perception health organizations are working to correct.

“Until recently, aerobic exercise was given the spotlight for improving health while resistance training was often omitted in global public health policy,” explains DJ McDonough, a cardiovascular disease researcher at the University of Minnesota School of Public Health. “But compelling research evidence has compiled over the years that makes it clear that resistance training confers a host of health benefits independent of aerobic exercise.”

This is why current guidelines from U.S. health agencies like the Centers for Disease Control and Prevention recommend spending 75-150 minutes every week on aerobic exercise and spending at least 2 days a week on muscle-strengthening activities.

What is resistance training?

Resistance training, also known as strength training, uses weights or resistance for the purpose of strengthening or increasing one’s muscles. While many people associate such resistance with lifting free weights like dumbbells or barbells or using machine-based exercises such as chest or leg presses, other forms of resistance also qualify. Bodyweight exercises like push-ups or sit-ups are other examples of resistance training; as is the use of elastic resistance bands that one can pull against to stress and build muscle.

Even everyday tasks like moving one’s body weight in and out of chairs, climbing stairs, or carrying heavy groceries and full laundry baskets count.

“Most of us are doing muscle-strengthening activities throughout the day without even thinking about it,” says Eric Shiroma, program director of the division of cardiovascular sciences at the National Heart Lung Blood Institute.

But it’s when a weight-bearing motion is repeated that muscle conditioning occurs. “As muscles adapt to resistance over time, they become stronger and more resilient,” explains Amanda Paluch, a kinesiologist in the life sciences lab at the University of Massachusetts Amherst. In such cases, she says it isn’t about building muscle alone, “it’s also about building a stronger body that is better able to function and thrive during our daily living.” 

Good for the heart

Research shows that adding just 30 minutes of resistance training to your workout routine each week could add years to your life, in part, by significantly improving your heart health.

“Strength training is great for your heart because it helps improve blood pressure and cholesterol,” explains Paluch.

It helps blood pressure by increasing blood flow and circulation, and lowers cholesterol by reducing inflammation. Chronic inflammation can lead to the buildup of cholesterol in the arteries, which is also associated with blood clots.

“And we have found that even less than an hour of resistance training per week is associated with a 40-70 percent of reduced risks of cardiovascular disease morbidity such as heart attack or stroke,” say Duck-Chul Lee, a professor of physical activity epidemiology at Iowa State University College of Human Sciences and a co-author of supportive research.

Good for the body

Strength training has also been shown to be helpful in many other body systems. And it improves balance and flexibility, despite perceptions to the contrary.

“Resistance training, particularly at higher loads, has long been perceived to increase body stiffness and reduce flexibility,” McDonough explains, “but a body of evidence now suggests the opposite; that resistance training is just as effective, if not more effective, than traditional static stretching at improving joint range of motion.”

Increased range of motion has been shown to improve balance and reduce the likelihood of injuries related to falls. Fredericson says resistance training can also decrease one’s risk of musculoskeletal injury or outside damage to internal organs as larger muscle mass provides a protective barrier or cushion between external forces and the bones and organs contained within the body.

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Resistance training has also been shown to strengthen joints and bones affected by medical conditions like osteoporosis and rheumatoid arthritis. This is particularly important for older adults as aging is associated with biological changes that decrease strength and skeletal muscle mass. Research shows that such losses diminish physiologic resilience while also increasing vulnerability to injury and disease. Resistance training counters this deterioration by stimulating the cells responsible for bone growth.

(Lifting heavy weights can help you mitigate osteoporosis. Here’s how to get started.)

It also counters the effects of sarcopenia—a progressive loss of muscle mass that often begins in the 30s or 40s in more sedentary individuals. Resistance training fends off sarcopenia by creating microtears in the muscle, which leads to fusion of muscle fibers that create greater mass, explains Monica Ciolino, a doctor of physical therapy at Washington University Physicians.

Strength training helps lower one’s risk of developing type 2 diabetes as well, and can help manage the disease.

“Muscle is our largest disposal site for blood glucose (blood sugar), so keeping it active and maintaining its size is important,” says Stuart Phillips, a professor of kinesiology at McMaster University. Paluch adds that this form of exercise “can also help your body use and absorb insulin better, which is crucial for preventing or managing diabetes.”

Resistance training further helps by allowing us to reverse muscle loss that results from sedentarily behavior during sickness, injury, or hospitalization. “Low levels of muscle function are associated with an increased risk for both disease and premature mortality,” explains Jeremy Loenneke, an associate professor of exercise science at the University of Mississippi.

Resistance training can also be helpful with weight management goals since lifting weights improves metabolism and because muscle tissue burns more than twice as many calories as fat tissue—even when a body is at rest. “While combatting obesity means a diet-centered approach, resistance exercise is as good or close to as good as aerobic training,” says Phillips.

Good for the mind

Strength training can improve mental health in several ways, including by improving sleep quality. Ciolino says it’s also been linked to protection against degeneration of parts of the hippocampus—a brain structure crucial in learning and memory.

The impact of resistance training on hormonal regulation further helps by warding off fatigue and by boosting one’s mood. “There is emerging evidence that strength training and resistance training may also be associated with lower rates of depression and anxiety,” explains Shiroma.

Where to begin?

Despite the advantages, some people neglect resistance training because they think they need to become gym buffs or require access to specialized training or equipment.

"The sheer number of different machines, weights, and exercises may make it intimidating and hard for some to get started," acknowledges Shiroma. "But muscle-strengthening activity may be more accessible than some aerobic activities since it can be done pretty much anywhere with either body weight or resistance bands."

To get started, McDonough says it's best to choose the type of resistance training that appeals most to you: weights, body, or resistance bands, and then learn a few simple techniques.

For instance, you can lift weights at your local gym, or you can buy a couple of dumbbells or kettlebells to lift at home. Once you get going, you may want to branch out and add a simple exercise bench and a barbell. When using weights, "a good rule of thumb for strengthening is that your muscles should be tired at the end of a set," says Ciolino, though she stresses the importance of learning proper techniques and not lifting too much, too soon. "Start with lighter loads and increase weight and repetitions over time," she advises.

Resistance bands can be purchased online or from local retailers and related techniques are easy to learn. "Even small amounts of resistance is all that is needed to get a large amount of the benefits associated with this form of exercise," says Loenneke.

When it comes to utilizing body weight, public health agencies have provided numerous videos and resources for learning proper form and techniques for exercises like sit-ups, push-ups, planks, lunges, and squats. Customized guidance from a personal trainer or physical therapist may also be helpful. Fredericson says guidelines support spending at least 30-60 minutes twice a week on strength training, but stresses that spending any amount of time is better than spending none.

"It is far more beneficial to begin a routine that you believe is sustainable than to focus on a perfect program," echoes Ciolino. No matter which routine you choose to follow, "resistance training is the antidote to the road toward frailty."