How can strength training build healthier bodies as we age? | National Institute on Aging

2022-07-15 19:45:19 By : Mr. Frank Zhang

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Some people perform incredible feats of strength and endurance well into their retirement years. The great news is: You don’t have to bench press 300 pounds or run a marathon to show off the benefits of strength training.

NIA-supported researchers have been studying the effects of strength training for more than 40 years and have identified multiple ways it can benefit older adults, including maintaining muscle mass, improving mobility, and increasing the healthy years of life. Learn more below about these findings from NIA-supported researchers, along with their tips for maintaining strength or becoming stronger as we age.

Some people have a hard time gaining muscle no matter how much they lift, while others have a hard time losing weight even when focusing on aerobic activity. This variability from person to person is another area of current research both at NIA and the institutions it supports.

Age-related mobility limitations are a fact of life for many older adults. Studies have shown that about 30% of adults over age 70 have trouble with walking, getting up out of a chair, or climbing stairs. In addition to making everyday tasks difficult, mobility limitations are also linked to higher rates of falls, chronic disease, nursing home admission, and mortality.

A big culprit for losing our physical abilities as we grow older is the age-related loss of muscle mass and strength, which is called sarcopenia. Typically, muscle mass and strength increase steadily from birth and reach their peak at around 30 to 35 years of age. After that, muscle power and performance decline slowly and linearly at first, and then faster after age 65 for women and 70 for men. Those findings come from NIA’s Baltimore Longitudinal Study of Aging (BLSA) — the longest-running study of human aging — which pioneered a series of simple tests decades ago, known as the Short Physical Performance Battery (SPPB), to track mobility and muscle performance. The SPPB measures an individual’s balance, walking speed, and ability to get out of a chair five times, and then rates that person on a scale of zero to four.

However, such average decline of strength and power with aging can be substantially slowed down by maintaining an active lifestyle. While there is no way to fully “stop the clock,” it’s possible for many older adults to increase muscle strength with exercise, which can help maintain mobility and independence into later life.

NIA scientist Eric Shiroma, Sc.D., has studied the science of exercise for years and is an advocate of activities that add an extra challenge in our daily routines, such as turning a walk into “rucking,” which means wearing a weighted vest or backpack while exercising. He notes that a big key to understanding the range of responses to exercise is knowing how and why our bodies change with age and, perhaps more importantly, how and why these changes can vary from person to person.

“As we get older, there are inevitable functional and biological limitations that can cap exercise endurance, maximum strength, and fitness,” said Shiroma. “Some of these limitations can be slowed down through an active lifestyle that includes strength training. However, it is difficult to study these limits in normal day-to-day life. Studies such as the BLSA are special because scientists can test these limits in the clinic. For example, to test strength and endurance, study participants may be asked to walk or run on a treadmill, or climb stairs, for as long as they can comfortably continue. There are also genetic and environmental components to how people respond to physical challenges and exercise.”

By studying people’s limits and variability, researchers aim to provide older adults with evidence-based advice on how regularly moving and challenging their muscles may help increase their years of optimal health.

Derived from the Greek root words sarx (flesh) and penia (loss), sarcopenia is defined as a decline in muscle mass, strength, and function. It is often associated with older adults, but some forms of sarcopenia can also affect middle-aged people. Sarcopenia has been connected to weakness; fatigue; lower energy levels; and difficulty standing, walking, and climbing stairs. Sarcopenia is more likely to occur in people with chronic diseases and may contribute to risk of falls, fractures, other serious injuries, and premature mortality. Poor nutrition and lack of exercise can increase the odds of developing sarcopenia. If you or a family member is feeling general weakness, talk with a doctor. It could be related to sarcopenia or another medical condition.

NIA-supported scientist Roger A. Fielding, Ph.D., associate director of the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University outside Boston, is a strong proponent of continuing to push our muscles as we age. He leads multiple studies aimed at better understanding age-related changes in muscle structure and function and how adding resistance training can prevent frailty and improve mobility and independence.

Fielding’s research has looked at how different types of muscle training exercises benefited a community-based group of older adults with moderate mobility limitations. According to Fielding, to understand the importance of maintaining muscle mass, it’s important to comprehend what’s going on inside our bodies when we exercise our muscles.

Strength training (also known as resistance training) is different than aerobic exercises such as running, cycling, or walking. Weightlifting, either with machines or free weights, is one type of resistance training. Other types include using medicine balls or resistance bands, or body weight-bearing exercises such as pushups, squats, or yoga. Resistance training requires our muscles to contract to lift a heavy object against the pull of gravity.

The more weight we contract against, the faster our bodies burn through reserves of adenosine triphosphate (ATP), a molecule that carries energy to cells. As we lift weights or do other demanding exercises, our ATP reserves are replenished through a complex, coordinated metabolic and chemical response that cascades through the entire body, including sparking short-term chemical changes in the DNA of muscle tissue that make them more tuned to specific proteins supporting sugar and fat metabolism.

Fielding and his colleagues have found that the best recipe for improving physical function and avoiding disability is a combination of walking and resistance training. In the NIA-supported research, older adult volunteers participate in small group exercise sessions led by a physical fitness trainer. Several of these studies were conducted at Tufts, but the program has since expanded to nearby Boston-area gyms and community senior centers. The goal isn’t a perfectly chiseled abdomen or achieving exceptional feats of strength. Rather, participants use different types of ankle weights and dumbbells, or adapt exercises as needed to use their own body weight.

When you do resistance or strength training, very important chains of molecules that relay signals between cells are affected, and these changes linger in the body for hours after exercise, building up a cumulative, positive effect. Even a low-intensity strength and walking program has substantial benefits.

The group sessions also encourage bonding and accountability among participants, which helps keep them motivated and sticking with it, according to Fielding and his colleagues.

Fielding doesn’t just talk the talk, he’s an advocate of strength training himself.

“I’ve always run three or four times per week, but, about three years ago, I started making strength training part of my routine, and I feel stronger,” he said. “My goal is to be able to do things I enjoy, including downhill skiing, as long as I can, and the best way to do that is to try to stay active.”

While strength training is great for otherwise healthy older adults, what about those who are overweight or living with obesity? NIA supported scientist Dennis T. Villareal, M.D., a professor at the Baylor College of Medicine in Houston, has found that incorporating weightlifting into an exercise and diet intervention for older adults with obesity yields better results than diet or aerobic exercise alone.

Villareal and his colleagues work with older adults with obesity, including volunteers from a nearby Veterans Affairs hospital and others recruited from the surrounding community. Their study participants are still functionally independent but are at risk of losing that ability.

“We work at the intersection of two big changes for society: aging and obesity,” Villareal said. “About one-third of older adults have obesity and that number is rapidly expanding.”

Villareal has been studying the nexus of muscle and metabolism for nearly 25 years. He got his start in the field in the 1990s at one of NIA’s Claude D. Pepper Older Americans Independence Centers. He helped with an exercise training study in frail adults over age 75 and was impressed with how it was possible for people to get motivated to exercise even at an advanced age. After losing about 20 pounds in recent years (thanks to a lower calorie diet combined with exercise), he himself experienced the benefits of weight loss, including more energy and improved physical fitness.

According to Villareal, it’s not well understood that older adults with obesity can also be frail, which creates a vicious cycle of mobility and independence loss as the years and pounds add up.

“Folks with obesity need more muscle mass to carry their body weight,” Villareal said. “When they get older, they can’t compensate by producing more muscle mass, so you get sarcopenic obesity, which is the worst of both worlds.”

Villareal’s year-long exercise training intervention known as the Lifestyle Intervention to Improve Bone Quality (LIMB-Q) targets this high-risk population. As people lose weight with diet and aerobic exercise, they have an increased risk of losing lean muscle mass and bone density, both of which are important for everyday activities and avoiding falls.

“That’s where strength training has an important role,” said Villareal.

Villareal’s team found that a healthier diet combined with a workout mixing aerobic exercise, resistance training, and balance was most effective for helping reverse frailty in obese older adults.

“Resistance training is the most important component because it builds muscle and reduces the loss of muscle mass,” he said. “As the relationship between body mass and muscle becomes more positive, participants lose more fat than they lose muscle, so the relative sarcopenia is improved significantly. Combining the two types of exercise had additive effects so they were better together than separate.”

One of the big rewards for Villareal and his team is observing participants who make positive changes and stick with them. Some volunteers have even exceeded the 10% body weight loss target, losing as much as 20% of their body weight. The weight losses combined with building muscle mean they feel better and become more independent and mobile.

Villareal notes that starting slow and attending regular group classes are important steps to building confidence and connections among participants.

The value and joy from group exercises is that participants motivate and encourage each other. Once the study is over, they are advised to continue to incorporate exercise into their regular routines. They often want to participate in other studies and become cheerleaders for the program.

In the future, Villareal hopes to explore the possibility of larger, longer-term studies to see if the intervention can prolong physical independence and delay the need for nursing home admission.

As if it wasn’t already tough enough to get and stay motivated to exercise, unanticipated factors such as the COVID-19 pandemic, severe weather events, etc., can prevent some older adults from going to the gym and exercising indoors with larger groups. To help overcome these types of barriers, a team of NIA-supported scientists from the Wake Forest University School of Medicine in Winston-Salem, North Carolina, is researching innovative ways to bring resistance training to the homes of older adults who are trying to lose weight. Investigators Barb Nicklas, Ph.D., professor, gerontology and geriatric medicine, and Kristen Beavers Ph.D., M.P.H., R.D., associate professor, Department of Health and Exercise Science, have developed a project known as Incorporating Nutrition, Vests, Education, and Strength Training in Bone Health (INVEST).

In previous studies of how to prevent the bone loss that comes with weight loss, Beavers and Nicklas saw that resistance training helped participants lose weight and become more fit, but it was hard for people to stick with the training long term. While not a substitute for traditional strength training, the researchers are now studying if wearing a weighted vest throughout the day can help prevent the bone-density loss that often occurs with weight loss.

INVEST participants wear their weighted vests for eight hours a day in addition to undertaking a 12-month weight loss program. The vests, which can be worn under one’s clothes, are lined with small rectangular pockets that hold one-eighth-pound incremental weights. When a participant loses a given amount of body weight, that same amount is added back to their vest. The compounding effect is to keep the skeleton loaded as excess body weight is lost, avoiding harmful loss of bone density that can increase the risk of fractures.

A pilot INVEST study showed that volunteers who wore the weighted vest as they participated in the weight loss plan also slowed down hip bone-density loss compared to the weight-loss-plan-only group. This support for how different ways to load and challenge the skeleton could reduce the risk of hip fractures, a common and often debilitating injury for older adults.

“The vest is also a nice ‘show-and-tell’ motivational tool,” Beavers said. “They can show friends or family, ‘Look at how much weight I’ve lost!’”

There’s no denying that our ability to respond to exercise gets blunted as we grow older. No individuals, even seemingly superhuman pro athletes who keep winning championships into their 40s, will have the same physical response to exercise at age 70 as they do at 30 or even 40. So, what is some bottom-line, realistic advice to keep strong and moving as we age?

Know what to expect. First, don’t try to compare yourself to younger people. Everyone is unique and we all age differently.

We all should think about how to build up a base of strong muscles to prepare for the loss of muscle and strength that we will experience as we age.

Nicklas notes, "A 60-year-old is very different from an 80-year-old. We need to be careful about lumping all older people into the same category. Aging starts at birth, and throughout our lifespans, exercising to help prevent disease and disability is very important. Movement, strength, and balance training is important at any age, but we need to adjust our expectations."

Move mindfully. Beavers points out that low bone density and muscle strength are associated with increased falls and fractures. Exercises that incorporate mindfulness with balance and movement, such as tai chi and yoga, can improve strength in these areas and help prevent falls and fall-related fractures.

Make it part of your daily routine. Villareal emphasizes that if online or in-person group classes aren’t your thing, everyone can still work exercise into their daily routines.

“We encourage people to just walk more,” he said. “Walk around the house or office, walk to the store. In the office you can take brief exercise or stretching breaks every 15-20 minutes and try to use all your muscles.”

Keep it fun. According to Fielding, “It’s about finding things that people want to do and like to do, not just exercise for exercise’s sake, but something we enjoy. Goal setting is also important. We ask our volunteers to list everyday things they want to be able to keep doing as they grow older, like play with their grandchildren or be able to take laundry up and down the stairs. Lots of things count as exercise: It doesn’t have to be running or going to the gym or riding a stationary bike. It could be dancing, gardening, or housework.”

He recommends NIA’s exercise and physical activity pages or the National Physical Activity Guidelines as good sources to help anyone get started.

Set realistic goals. Fielding noted that everyone is different and it’s not one size fits all.

“Some like group exercise, others prefer a solitary routine to clear their head,” he said. “But setting realistic goals is important. A good goal is about 150 minutes per week of moderate-level exercise, but you see benefits even at lower levels than that. Older adults should try to get strength training in the mix one to two times per week.”

The bottom line is to get moving.

“Any physical activity is better than no physical activity. Even a couple minutes per day matter, and small changes lead to big improvements.”

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