Why We Lose Muscle–And How to Keep It

0:00 Hey everyone, this is Sony Cassm, host of 1440 Explores. Today I'm handing things over to my colleague Dena Fine Marin, 1440's health and medicine editor for an episode I'm pumped about. I'll be back next time. Enjoy. It seems like everyone is trying to get fit these days. Plank holds in yoga, dumbbell swings, tricep dips, push-ups. So-called strength maxers even make promoting strength their personal brand. And a growing body of research says they're on to something. Strength training prevents frail in our old age, wards off cognitive decline, improves glucose control, and more. We see that people who do resistance training tend to have better mental health outcomes,

0:45 tend to sleep better. >> But how does that all work? Why is there so much buzz about it now? And how can we incorporate these exercises into our lives? Today, the science and history of getting strong, why we pursue strength, [music] how resistance training compliments aerobic exercise like running or swimming, [music] and how attitudes towards strength training have evolved, from ancient Olympians to circus spectacle [music] to long-held fears that big muscles make athletes stiff and slow to the current push for more [music] muscle in the era of GLP1. We'll dive into all of this and more with the help [music] of two experts, Daniel Lieberman, a human evolutionary biologist at Harvard University, and

1:31 Amanda [music] Paluch, a kinesiologist who studies physical fitness at UMass Amherst. I'm Dina Fine Marin, and this is 1440 Explores, a show where we unpack elements of our daily lives. Stay with us. Let's start with the basics. There are two main kinds of exercise. First, there's aerobics. You may know this as cardio. It's called that because it gets your heart rate up. Think running, swimming, dancing. With those types of exertions, the heart is forced to push more blood to your muscles. And over

2:18 time, that makes your heart stronger and more efficient. Then there's resistance training, aka strength training, pumping iron, really anything that works our muscles against an external force. These keep your muscles and bones fit. And though we're all encountering some degree of resistance in our daily lives thanks to gravity, it's simply not enough on its own. So that's where weightlifting and lunges come in. Here's evolutionary biologist Daniel Lieberman. When I'm running, my legs are hitting the ground only for a very brief moment of time. It's not that much resistance. But if I'm bench pressing something really hard, I'm now pushing against a lot of muscles which are contracted and I'm now having to push that blood through a lot

3:04 of contracted resistant muscles. >> So, how does this all come together to make us fit and healthy? Let me take you through some of my sweaty daily workout where different movements all work in tandem. Take bicep curls, which I'll do right now while we're recording. So, I have two weights, one in each hand. When I pull the weight up, it generates force while shortening my muscles. When I lower the weights, my bicep lengthens under tension. And when I extend the dumbbells out and hold, that's another type of resistance movement. After doing multiple sets of exercises like that, my arms feel tired obviously. But inside my body, something interesting is happening. All those reps lifting heavy

3:51 objects causes tiny tiny tears in my muscles. My body rushes to repair those tears, but not just back to how they were before. No, the continual cycle of repairs leaves my muscle fibers thicker and stronger. And as this is going on inside the body, muscles are adapting to these increasing demands by improving their efficiency in numerous ways, including increasing the number of mitochondria, teeny tiny energy factories inside muscle cells. The end result, bam, strength. With resistance training, muscles are working well because the stress that was put onto them kicked cellular repair processes into gear. inflammatory processes were successfully signaled. But what does

4:37 that mean exactly? The immune system sends a wave of proteins and hormones along to check out what's going on and contain any foreign substances, clear away cellular debris, and initiate repairs. So, the inflammatory process is helping you heal, but it's also responsible for making you feel sore. That feeling is a byproduct of the system working as it should. It's a direct signal from our immune system to our brains saying rest and it's doing the essential checkup and repair work. >> By not resting in between workouts, you basically work against the body's processes that are trying to help you stay healthy and keep that muscle healthy. >> So, what happens if you don't use those

5:22 muscles if you don't pump iron regularly? You lose those muscles. Sadly, it is a use it or lose it situation. >> If you have extra energy, natural selection always wants you to save that energy and use it for reproduction. So that's why when we don't use our muscles, our muscles naturally shrink because you want to use that muscle for something else. There's no point in having extra muscle. It's just waste, right? [music] So our muscles shrink if you don't use them. But the other flip side is that when we do use our muscles and we demand more of them, we have a an adaptive system that causes the muscles to then grow stronger. >> It doesn't matter who you are or what stage of life you're in, weight training can make a big difference. >> There are studies which give 90 year

6:09 olds, I'm not making this up, 90 year olds strength training and they can generate muscle. You never lose the ability to generate muscle. For my purposes, the goal is maintaining and maybe building a little muscle mass, remaining fit, avoiding osteoporosis and old age frailty. Doing reps of my workout routine improves my ability to use those muscles repeatedly over time, aka my endurance. But let's say you do want to bulk up. As you increase the weights you lift, boosting your muscle load over and over, assuming you rest in between and eat enough protein, your muscles will get more and more efficient, and they will grow. To build strength, you'll need

6:55 progressively heavier loads, [music] requiring stronger contractions, not just more of them. Our ancient ancestors weren't thinking about [music] getting swole, though. There was no strength maxing, no [music] looks maxing. In fact, our ancestors would never purposefully exercise. They had enough work avoiding predators. And maybe they incidentally experienced resistance workouts from carrying heavy loads like game they'd killed. Here's Daniel Lieberman. >> Your typical hunter gatherer walks between 5 and 10 miles a day every single day their whole life, right? And

7:41 they're also doing vigorous physical activity like occasionally running and uh you know climbing trees and things like that. >> Most of us are not living that way and all of us are losing muscles as we age. On average, we lose 3% of our muscle mass each decade after turning 30. It turns out no matter how much exercise we do, we'll still lose some of our muscle mass. That's just life and part of aging. But it's also partly the fault of our shift to modern conveniences like computers and office culture where workers sit all day. >> We have managed to make machines for pretty much every single activity you can think of. And the result is that we don't use our bodies very much anymore. And so now we've had to create this thing called exercise. And exercise is

8:28 discretionary. I define it as discretionary and voluntary physical activity for the sake of health and fitness. This is a completely modern thing. We never evolved to do it. >> But science is making clear that beyond putting our bodies through their paces, there's more happening that we can't see when we exercise in our immune system. >> If you aren't physically active, you don't build capacity and you don't turn on all kinds of repair and maintenance mechanisms that are crucial to keep us staying healthy as we age. And so lack of physical activity both endurance as well as strength is what we call a mismatch. Something that we are poorly adapted to and it leads to all kinds of problems from diabetes and heart disease and cancer. So we need to turn on those repair and maintenance mechanisms with exercise. But how? Researchers have spent decades making

9:14 connections between [music] how we move and assessing the physical and the mental benefits. They've developed the science that establishes that resistance [music] training is useful and determining how much seems like a good idea to keep us fit and healthy. They've done the same for cardio exercise. And all that work [music] led to expert federal exercise recommendations. We'll get to those guidelines and more in a moment. But first, let's take a look at the surprising history of how we viewed strength through the centuries [music] and learn about some very, very strong people. That's next. After the hunter gatherers of Yore and

10:00 the weight heavy work of being farmers, strength training mostly was an issue of military readiness. >> Think about the origins of the Olympics. A lot of the Olympic games were about training soldiers to be athletes and athletes [music] to be soldiers. Take Milo of Croton, the most famous wrestler in Greek antiquity. He won in the Olympics over and over more than 2500 [music] years ago. How'd he train? As legend has it, he carried a calf each day from its birth until it grew into an ox. That would be some serious strength training, [music] right? An adult ox can be more than 1,000 lb. Moving beyond the gymnasium in roughly the same era, Hypocrates put forth the idea that

10:46 exercise was medicine. He was the first recorded physician to provide a written exercise prescription. In that case, for a patient suffering from tuberculosis. Then in ancient Rome, there was also a clinician named Galen, a physician of gladiators. He called for moderation and exercise, so giving the body time [music] to rest. He also urged people to do what today would be called resistance training, telling them to work out with small hand weights. And his ideas had staying power. Galen's exercise advice and writings influenced healthc care for warriors and standard citizenry alike until the 16th century. That's not to say strength maxing really took off in the Middle Ages. Too much strength through the lens of Christianity at the time was viewed as a

11:32 physical vanity issue and was generally frowned upon in most people. And pervasive cultural beliefs about physical strength being the stuff of weird, vain, or even dim-witted people generally lived on and tainted the appeal of resistance training well into the 20th century. It was the stuff of circus sideshows, a spectacle. And unfortunately, even more so if a woman displayed any sort of impressive strength or obvious muscles. Then there was the Italian-American bodybuilder Charles Atlas. [music] In the 1920s, Atlas created and marketed a mail order bodybuilding course. People absolutely sent away for his mail order courses. But the mainstream idea in

12:18 medicine and society still continued to be big muscles were well weird and unhealthy. The standard take from the Victorian era [music] through the mid 1900s was that strength training and building muscle was bad news. Why? Physicians and athletic coaches warned you could become muscle bound. The first known use of the word was in 1879, and it eventually led to widespread ideas against heavy lifting in general. The idea, which has since been disproven, said you'd become stiff. Your muscles would be cumbersome, slowing your ability to perform well in sports competitions and in your daily life. So, sprinters, they said, just stick to

13:05 running. Look, there there are still people who think that way from a biomedical perspective and an anthropological perspective. My worry is just yeah, just keep staying healthy, right? Um that's my concern. >> What really changed things for medicine and culture around resistance training? Part of it was well science in the mid- 20th century. Anecdotally, athletes doing resistance exercises didn't see their speed decline. In fact, they got faster. and researchers eventually ran structured trial tests and confirmed that speed and flexibility didn't suffer from having more muscles. The other part though was World War II and injured soldiers. There was a US Army physician named Dr. Thomas Delarm and he did something revolutionary. He prescribed what today we'd call progressive

13:52 strength training with sets and reps. He did some of what Charles Atlas did and nodded to what Milo did with a calf, but he suggested it's worth doing all that for rehabbing soldiers and importantly that it was worth studying the results. So, this turned purposeful strength training, what we call resistance training, into something worth doing, something standard, something to be valued. Beyond scientific advancements, culture needed to shift, too. ideas about what beauty was, how being toned or muscular could fit into our views of what we want to look like. That came in incremental waves with Venice Beach's rising popularity in the 1960s, with Arnold Schwarzenegger in the 1970s,

14:38 with workout television shows of that period, and eventually with exercise movements such as CrossFit. >> I've been to CrossFit gyms. I love going to CrossFit gyms and that's kind of like a tribe, right? you know, they it's almost like a religion. >> But for Daniel Lieberman, resistance training isn't about being toned. It's not really about finding his tribe. It's more personal. >> Basically, my both my parents ended up dying by falling and they were both extremely physically active people, but but for various reasons, they they ended up losing muscle mass and and it was really hard to watch. You know, nobody wants to be in that kind of position. And and the problem is that by the time it happens, it's not completely too late, but it's much harder to get the muscle back. The best thing to do is to not lose the muscle in the first place.

15:25 >> So that's how resistance exercise moved from everyday activities to the gymnasium and military training to societal fringe and then to the aftermath of the battlefield rehabbing soldiers. It's led to circuit training regimens and gyms and popular videos online. Put simply, it's gone viral. And that brings us back to the official exercise recommendations for American adults. They state [music] adults should complete 150 minutes of cardio weekly and two sessions of resistance training for every muscle group. That includes chest shoulders back arms abs legs. Here's Amanda Paloo at UMass Amherst. So how the the guidelines are developed is they bring a variety of experts together

16:11 and they really dig into the data from both observational studies and also clinical trials and look at a variety of health outcomes. And what we see is say we have these trials where we give individuals different days per week, different minutes per week of activity, and we see that the majority of the benefit is around 30 to 60 minutes per week or 2 days per week of resistance training. She didn't help write those guidelines, but she chaired a scientific committee at the American Heart Association charged with reviewing the available science and putting out the group's 2023 official statement on resistance training. Basically, they said they're huge fans of the stuff. Resistance exercise, they said, is

16:58 really important for heart health, sleep depression anxiety blood pressure, and the list goes on. So the top level message is that two days per week of resistance training of about 20 minutes per session leads to all essential cardiomatabolic benefits. Compared to individuals who do absolutely no resistance training, those who reported doing 30 to 60 minutes per week of resistance training were at a 15% lower risk of premature death. I mean, that sounds really great, but in America, about 75% of us aren't doing our recommended cardio and weight training. 75%. >> It's a natural instinctive disincclination to do this. The

17:43 beginning of any conversation is to acknowledge that there's nothing wrong with that person. They're not abnormal. They're not lazy. They're actually completely normal. But we live in a world where we now have to overcome natural instincts and do something which is intrinsically and fundamentally unnatural. >> Though our inactivity may sound kind of depressing, it turns out we're actually on an upward swing. Our most recent federal data suggests about 30% of adults are completing the strength training recommendations, up roughly 10% from a decade earlier. Amanda has some ideas to help get more people moving and boosting our strength. So that's why I'm the big proponent of at home exercises for resistance training, walking for aerobic training where you don't need equipment, you don't need a fancy outfit

18:30 to get out there. Say if you're watching television on YouTube, see if there's a way that you can integrate also getting in your lunges, your 20 minutes of resistance training twice a week. I think that that would go a long way. Plus, she thinks that resistance training for many of us may be a sort of lowhanging fruit as compared to cardio. 20 or 30 minutes twice a week versus cardio 5 days a week. Maybe it's our exercise gateway. The most important thing, she says, is developing exercise routines that can become a habit, ones we'll actually stick to. No matter what we end up trying, science says every bit can help.

19:16 We can [music] work out at home with water bottles as our weights. We can, if we can afford it, sign up for a session with a personal trainer [music] to get some tips. We can turn to the internet for workout videos. Yet, even as we're all supposed to be exercising more and kicking our inflammatory responses into gear, the science is accumulating that says chronic inflammation should be avoided. It's linked to numerous diseases of aging. So, how do we square the two? Strength training being good for you multiple times a week alongside even more frequent cardio, but a chronic level of inflammation actually not being good for you. Amanda says, "When we work out, we're triggering an acute inflammatory response which repairs our muscles and allows us to get stronger. But if we're

20:03 constantly working out and not resting, then that leads to chronic inflammation, the kind that's more commonly associated with autoimmune disorders, and that can be harmful longer term. Workout goals and needs vary between individuals, and we should all consult our doctors before beginning a new regimen, but exercise physiologists recommend starting the practice early. It benefits women in menopause in particular because estrogen reductions can lead to bone density loss and that boosts the chances of osteoporosis and bone breaks. What's more, in this era of GLP1 with so much excitement over this class of weight loss drugs, experts warn it's essential for people on that medication to make sure they engage in strength training. If you're eating less and you're losing

20:48 weight, some of the weight you're losing is going to be muscle. So, you need to stick with or start resistance training. At its best, doctors see that together, strength training and cardio, they work. Put the energy in at the gym or at home in your basement, and muscles bloom over time. You can run faster, your heart won't hammer out of your chest when you take the stairs. But how exactly can all this exercise benefit not just your muscles, but also your mind? Here's Daniel Lieberman again. For example, when you exercise, your your skeletal muscles produce a molecule called BDNF, brain derived neurotropic growth factor, BDNF. And it's like miracle growth for your brain. It it causes brain cells to regenerate in certain parts of the brain like the hippocampus, which is where

21:34 memory is seated. >> That mechanism of action makes sense even as many of the studies looking at exercise and its benefits are often showing correlations between the two, not direct causation. What we do have are a combination of epidemiological studies and there are many of them all right hundreds of them now which show extremely strong statistical associations between physical activity both strength training as well as cardio and people's long-term health outcomes >> and that touches on why resistance training shouldn't come at the expense of cardio. And by the way, there's a lot of evidence that people who do a lot of resistance training, it's great. But nobody should just do resistance training and not do some cardio. There's a reason it's called cardio. It's good for your cardiovascular system in ways

22:21 that in that resistance training is not, right? I think everybody should do a mixture of everything. What that mix is exactly is dependent on all kinds of factors including what you like to do because obviously most of us end up doing what we like to do. >> So it's all about building habits. But no matter how much we exercise, we will still age. Our bodies will still break down somewhat. [music] Yet, we can help move the curve over so that we experience those losses more slowly, our chances of disability declining. So, the real question at the end of this story is not if resistance training is useful, since it obviously is. The question is how we can make it work in our lives so that we can remain capable for as long as possible.

23:07 Carrying our own groceries, climbing the stairs, getting up from the couch. The encouraging part is that building that capability doesn't necessarily require a gym or an exercise class. It can start with push-ups in the kitchen, weightlifting water bottles, or doing lunges while watching YouTube. Because decades from now, those repetitions will matter more [music] than we realize. >> Health span is how long you live. You know, being able to do the things you want to do without disease. And people who exercise, not only do they have longer lifespans, but especially important, they have longer health spans. Many thanks to Daniel Lieberman and Amanda Paloo for joining us in today's

23:53 episode. And thanks to all of you for listening to 1440 explores. I'm Dina Fine Marin. Make sure to follow the show and leave a review on Spotify, Apple, or wherever you listen to your podcasts. And let us know what you thought of this episode at podcasts at join1440.com. 1440 Explores is a production of Rhyme Media for 1440 Media. This episode was produced by Nicolo Minoni and edited by Dan Bobkoff. Our fact checker is Alice Jones and our sound designer is Jay Cowit. The executive producer at Rhyme is Dan Bobcoff. And the executive producers at 1440 are Sony Cassam and Drew Stigerwald.