Why Exercise Slows Aging | Lifespan with Dr. David Sinclair

Fitness, Longevity, and Lifespan.com Community Low fitness predicted mortality more strongly than smoking, diabetes, hypertension. Those in the lowest fitness percentiles have 4:00 to 5:00 fold higher risk of death compared to those in the highest percentiles. Humans evolved to move. Our biology expects it. When movement disappears, systems drift out of calibration, we age more rapidly, and the problem is exercise does not fully offset prolonged sitting, so moving from nothing to just something delivers a large return on investment. Welcome to Lifespan, a show where we discuss the cutting edge science of aging and how to live healthier at any stage of life. I'm David Sinclair, a scientist and professor working on understanding why we age and discovering new ways to slow and even reverse the aging process. On this show, I share an insider's look at the latest from my lab, the field, and what's just around the corner. Hey everyone, welcome back to Lifespan. I'm so excited for you to hear this episode. Actually recorded it with the team very late at night after being in the lab all day and the team was amazing. This episode, Part 2 of Physical Activity and Exercise, explores exactly why physical activity is so good for us. What you might not see on camera is how Marissa, our chief of staff, really showed us men how the sitting rising test is actually done properly. We're going to talk about in the episode, but off camera we were trying to see who was best at it, and it was awesome to see her do it so easily. But honestly, it was pretty embarrassing for us guys, including Andrew and Rajeev here. Sometimes it just takes me reading a new powerful paper on the science of exercise to nudge me to get off my butt even more. I really want to thank and credit the whole Lifespan team's combined effort in making what I believe is the most accurate source of evidence based health information you can find anywhere. And as always. Speaker 2 The Lifespan team and I really appreciate you hitting the subscribe button. I'm so excited to share that our health and education [email protected] is now live. The mission of the site is simple. It's to help you and your loved ones live your longest, healthiest life. When you join us at lifespan.com, you'll get early access to Lifespan episodes, a newsletter from me and updates about the clinical trials, comprehensive show notes, and what I'm particularly excited about is that you'll receive Lifespan Magazine, the world's first longevity magazine written by scientists. We also have Ask Me Anything Sessions, a book, miniseries and movie club, behind the scenes content, and much, much more that's coming. I couldn't be more excited. Lifespan connects you directly with the longevity scientists doing the research so you can understand the science and apply it to your life. We're making the best evidence based health insights accessible to everyone and building the world's largest longevity community. Lifespan is proud to support the Lifespan Foundation, a non profit whose mission is to fund the careers of young researchers and to support the most exciting longevity research. So do join us at lifespan.com. Speaker 1 And let's live longer together. So now let's go. Exercise Triggers Molecular Pathways for Longevity Today we're going to talk about physical activity. We're going to look at exercise from a perspective you might not have before and dig deeply into the science, discussing what's real and what's not. Of course, we all know exercise in its various forms is one of the most reliable ways to live longer and delay most diseases, including disability and frailty in older ages. There are a lot of things that I didn't know until I really dug in deep and there are things you probably heard on the Internet, on social media that are patently untrue. Cardio respiratory fitness, which is your body's ability to deliver oxygen to your muscles and keep going, is one of the strongest predictors that we have of long term health and survival. And one of the most reliable ways to maintain cardio respiratory fitness is to be consistent with intentional movement. Exercise also preserves muscle mass and of course strength, endurance and even power. These are qualities that naturally decline with age, especially over the age of 40, unless we actively counteract them. And stronger muscles don't just help you lift groceries, they help you stay independent, maintain balance, and avoid frailty decades later. Movement influences nearly every biological system, so with sensible regular activity, you think more clearly, feel better, regulate your metabolism more effectively, and support your immune system. That's why metrics like VO2 Max track your biological age more accurately than even years on your birth certificate. First, I want to answer a simple question that we often don't ask because we take it for granted that exercise is good for us. Why does physical activity make such a difference? Why is it such a core pillar of a longevity lifestyle? Under the surface, exercise triggers molecular pathways that govern how long and how well we live. When we're inactive, sit around all day, or just overeat, our biology shifts into what I've called abundance mode. And if you've listened to any of the podcast, you'll know about this. This is when repair pathways such as AMP kinase and the sirtuins which we work on, they shut down, they go quiet relative to growth mode. Exercise reverses that by putting our bodies in what I call adversity mode. It activates ancient survival circuits like AMP kinase and the sirtuins on the repair side and emptor to maintain and build muscle when appropriately balanced. Exercise is hormesis in action, and hormesis is essentially what doesn't kill you, makes you stronger and longer lived. It's a controlled biological, not psychological, but biological stress that tells our cells and our tissues to prepare, repair and be more resilient. Our Ancestors Moved Constantly for Survival The story of why physical activity is so good for us begins more than two million years ago. It's important to know where we've come from, to know how to live the best life we can and where we're going as a species. We didn't evolve sitting at desks, of course, or staring at screens. We evolved to move constantly. Our ancestors walked. They climbed, ran, carried babies, carried food, tracked animals, and explored daily because movement meant survival with two legs instead of four. We were never the fastest hunters on the plains of the Serengeti, but we were the fittest. Evidence from modern persistence hunters, like the San hunters in the Kalahari give us a good idea of what our ancestors lived like. There was two to six hours of continuous hunting every day. There was alternating jogging, fast walking, and often during the heat of the day they were out when prey were overheating. The fastest early humans could cover 10 to 15 kilometers per day, not for fitness goals, but because survival demanded it. We could outlast almost anything. And this is where persistence hunting or the endurance pursuit hypothesis comes in. The idea is simple. Humans could chase prey for hours in the heat until the prey overheated. A healthy antelope can Sprint far faster than a human, but it cannot sweat efficiently. Eventually its core temperature rises to lethal levels. We are such an unusual species. We have sweat based thermoregulation with millions of Akron sweat glands and other species just pant. We lost our hair, some more than others, to enhance the cooling of the body. We have relatively long legs compared to other primates, and our spring, like Achilles tendon, stores and releases elastic energy. The nuchal ligament at the back, here now used for reading phones, is important because it helps steady the head during motion. We don't just look different, even inside our cells, we're different. The mitochondria, those metabolic powerhouses support long duration activity. Movement upregulates genes like PGC 1A, which stimulates mitochondrial Biogenesis, the number of mitochondria that's in each cell and variants of the ACT N 3 gene influence fast versus slow twitch muscle performance and regular physical activity. Boosts BDNF, supporting neural health and plasticity. We humans are really built for endurance. Early humans lost the function of the CMAH gene about two to three million years ago, and this is likely linked to increased endurance tolerance compared to other mammals. This gene change removes a sugar molecule called Nu 5 GC from our cells on the outside, and this may have increased oxygen use and fatigue resistance relative to other primates. The same mutation has been LinkedIn some studies to enhanced inflammation and cancer risk when consuming red meat during immune reactions to this new 5 GC which is absent in humans. Just recently in July 2025, there was a study by Macaque and colleagues published in Nature Communications and they found that a gene variant inherited from Neanderthals affects the AMPD 1 enzyme and this helps muscles recycle energy during activity. The title of the paper is Muscle AMP. D aminase activity was lower in Neanderthals than in modern humans. So modern humans, those who carry this Neanderthal version, have lower enzyme activity, meaning their muscle cells are less efficient at regenerating energy during sustained activity or intense exertion. This variant is found in a small percentage of people outside Africa, in about 8% of Europeans and about 2% of South Asians, and it's absent in Africans and East Asians. So why does this matter today? For those of us with an active lifestyle and our ancestors, this variant of the gene may have little downside. But in a sedentary environment, if you don't exercise enough, this variant may suddenly reduce exercise performance and energy metabolism, making it harder for the carriers of this variant to benefit as much from physical activity as people without it. Mismatched Theory: Exercise as Medicine & Social Bonds Now this brings us to what's known as the mismatched theory. The idea that we evolved for regular, varied movement spread across the day. Not structured workouts, but far more physical activity than the modern life typically demands. Walking, lifting, climbing, sprinting, carrying, playing. These weren't hobbies, they were daily survival tasks. At the same time, evolution also wired us to conserve energy. Food was really unpredictable, so our biology learnt to favour rest whenever possible. That impulse kept our ancestors alive. But it's also why exercise can feel unnatural. We like to rest. If you're like me, it's hard to get moving. We just weren't designed to jog on treadmills while staring at walls. We were designed to move with purpose within a team, to hunt, to forage, play and explore. So Fast forward to the modern world. That ancient signal to conserve energy is still there, but the environmental pressure to move is gone. Instead, we have chairs and cars and screens, elevators, delivery apps. Even our suitcases have wheels on them. The result is a profound mismatch between what our genes expect and now how we live. Hunter gatherers only sit around for about 3 to 4 hours a day. Contrast that with today's world. The typical US adult sits for up to 9.5 hours a day, either sitting down or lying down. For office workers, it's even worse, 10 to 12 hours a day. This includes time spent working at a desk, driving, watching TV or streaming, and using our phones, of course. And computers. And this doesn't even include sleep. Rates of cardio metabolic disease rise sharply as movement declines, particularly when modern diets are layered on top. This doesn't mean ancestral lives were easy or disease free, of course. They still had infections. Trauma and childbirth claimed many lives, but it does highlight how dependent humans are on movement to maintain function. So yes, modern life has pushed us out of sync with our biology and our genetics. And the solution isn't fighting our biology, it's restoring it. So when we choose to move, we reactivate systems that evolved to keep us resilient. You've probably heard the phrase exercises medicine. I'd argue it's even better than that. Most drugs target 1 pathway or one symptom. Physical activity works everywhere. It improves the health of our heart, muscle, metabolism, immune system and even our brain. So when we stop moving, the body shifts into storage mode and what we also call abundance mode. The excess nutrients are shunted into fat and repair pathways come down, inflammation goes up and physical capacity just erodes over time. Importantly, even small amounts of movement and activity, they reverse that signal, redirecting energy towards maintenance, repair and longevity. Exercise provides a control, transient biological stress that tells cells to adapt. Over time. Our body becomes harder to break, and movement was never meant to be solitary. We humans evolved to move together, whether it was when we were walking, hunting, gathering or even dancing. Physical activity strengthen not only our bodies but our social bonds, and even today, moving with others enhances our adherence, motivation, and psychological well-being. There's also the active grandparent hypothesis. In ancestral societies, physically capable older adults who could move, teach, carry, and protect likely improved the survival of all their offspring and the multiple generations after them. Staying active later in life may have conferred evolutionary advantages that extended well beyond the individual. So now let's talk about exercise and energy burn. Exercise, Calories, and Hunger Regulation Explained This is where our intuition often clashes with the actual data. For years, the dominant idea was that total daily energy expenditure is capped and that if you burn more calories exercising, the body then compensates by spending less energy elsewhere. The recommendation was you don't need to overdo it because it will be a waste of time. Some of the strongest early evidence cited was from studies of the Huds of people, a modern hunter gatherer population in Tanzania. Despite walking long distances daily and living highly active lives, their total energy expenditure, once adjusted for their body size, was like that of people of industrialized countries. The interpretation was that humans may reallocate energy away from other physiological processes such as immune activity, reproduction, background, inflammation, to keep total energy burned within a relatively narrow range. But this view is changing. More recent research suggests that humans have a higher metabolic ceiling than other primates. What this means is we can actually increase our energy expenditure through activity without impacting these other hard constraints or even affecting other systems that we need to survive. A 2025 PNAS study. Proceedings of the National Academy of Sciences, titled Physical Activities Directly Associated with Total Energy Expenditure without Evidence of Constraint or Compensation, found that across typical activity ranges, people who move more truly burn more. Wristing metabolic rate was not suppressed, and participants did not compensate by moving less the rest of the day. This supports a more additive view of energy expenditure. The authors of that paper suggested that earlier findings of strong compensation were probably influenced by less precise measurements. This does not mean that exercise guarantees weight loss. It does mean, though, that you should combine exercise with precise control over how much you're eating. Exercise thermogenesis, The calories you burn through movement and exercise typically accounts for only 5 to 15% of your daily energy expenditure for most people, which is surprising. I thought it would have been a lot more than that. There are actual practical limits to how much intensity and volume can be sustained. And as fitness improves, efficiency increases, meaning you burn fewer calories doing the same work. After intense exercise, your appetite is actually influenced by a number of hormones and metabolites. Initially you won't feel hungry, but later on you might find that you would get really hungry. I certainly feel that way. There's a special exercise induced metabolite called Lac Phi, which is, I mean it's complex name is N lactol phenylalanine. But that doesn't matter. What's important is very recently it was discovered as a hunger suppressing molecule that gets induced by exercise. First published in June 2022, it's produced when lactate and the amino acid phenylalanine combined during vigorous workouts. This combination is what suppresses your appetite in part. Speaker 2 One thing that's important to me is that Lifespan only partners with companies that I genuinely believe in. They must be grounded in science and willing to support medical research that will ultimately change how we treat aging and diseases. Their support also helps keep this podcast free for millions of listeners around the world. One of those companies that I'd like to mention is Ketone IQ. I've known the founder, Mike, for over 5 years and I'm a huge fan of what he's doing. I've been studying the benefits of fasting for over 25 years now, and one of the most important molecules is beta hydroxybutyrate, or BHB, the primary ketone that our bodies make during fasting. That's an important metabolic fuel for your brain and your muscles. More recently, science has shown that BHB is also an epigenetic regulator of your immune T cells. These are cells that protect against viral infections. Ketone-IQ is a little shot that contains R13 butandiol, a naturally occurring molecule that your liver converts into BHB and it happens in minutes instead of the day or two it normally takes through fasting. One of the studies on BHB that caught my attention recently was by Stephen Kernane and colleagues. Their work in 2016 showed that while the aging brain loses its ability to use glucose efficiently, its ability to use ketones remains largely intact. That finding has helped spark an exciting new area of research on brain metabolism. And more recently, Quinonius and Bleman published a randomized trial in 2022 in the journal Nutrients showing that ketones help preserve reaction accuracy during prolonged, mentally demanding exercise. And another study in that same year found that patients with severe COVID-19 had impaired ketogenesis, the ability to make ketones. In their experiments, adding BHP improved both the CD4 and CD8T cell functions, suggesting that ketone bodies may help restore antiviral immune responses under those conditions. Personally, I use Ketone-IQ quite often when I have a long day, when I'm recording podcasts I'm writing or I'm feeling a little down or maybe getting a virus. I'd love you to try Q10 IQ too. I asked the guys at the company to offer a 30% off discount for your first monthly order, which they kindly agreed to. You can visit ketone.com/lifespan or at the checkout. Just use the code Lifespan. Speaker 1 After you've done vigorous exercise, you've used up stored fuel like glycogen in your muscles, and your metabolism is working to recover and restore the balance. As a result, your brain and your body begin to trigger signals that say we need food to refuel those reserves and support recovery. One of the key players is Ghrelin. The classic hunger hormone that rises when energy stores are low and it tells your brain that you want to eat. Meanwhile, hormones that normally make you feel full, like peptide, YY or PYY and GLP one which we've all heard of now, are temporarily altered or returned to baseline once the immediate post exercise period passes, reducing their appetite suppressing effect. And that's when hunger sets in and we tend to go to the fridge to see what's in there. Endurance, Strength, Power, and Functional Movement So we've talked about what inactivity does to the body and how it's a mismatch with our genes from our ancestors. But now let's flip it. How good is movement? Movement and exercise are some of the most broadly impactful interventions we know of. 1 behaviour, many effects. So when people talk about being fit, they often mean one thing. But fitness is multi dimensional. We need endurance, Strength, speed, balance, mobility, coordination. Each of these contributes to how well you function across your lifespan. Cardio respiratory endurance, for example, reflects how well your heart, lungs, blood vessels, and mitochondria work together. Muscular endurance determines how long you can sustain effort. Strength is the ability to generate force, of course, and power is how quickly that force can be expressed. Balance, stability and coordination protect against falls, while mobility and flexibility preserve range of motion and reduce injury risk. These qualities don't exist in isolation. They interact, and neglecting one eventually limits the others. So when you say fit, you really should consider all these aspects of your health. There's no single best type of exercise for longevity. Just as with nutrition, variety and consistency matter. A balanced movement diet, quote UN quote, that you enjoy and can sustain for decades beats any optimal program that you're just abandoned after two weeks. Aerobic exercise, brisk walking, running, cycling, dancing strengthens the cardiovascular system, it improves insulin sensitivity, and it supports mitochondrial health resistance training. Weightlifting preserves your muscle mass, bone density and metabolic function. Both of these types of exercise are non negotiables for healthy ageing and a vigorous life over 80. Power training deserves special attention Here we lose power, the ability to generate force quickly, earlier and faster than we lose strength. This loss contributes to falls, frailty and loss of independence later in life. Appropriately scaled explosive movements help preserve this capacity. Stability training, such as standing on a platform and maintaining your balance. It improves neuromuscular control and reduces fall risk later in life. Coordination training sharpens motor patterns and maintains brain body integration. Flexibility and mobility work together to improve joint health and movement efficiency. Actually I write about this in Lifespan the book, a Brazilian study using the sitting rising test or SRT, which is basically you sit cross legged and you have to stand up in one movement. It showed that people who could do this without using their hands or getting on their knees or even a chair had substantially higher survival rates. First published scientifically in the European Journal of Preventive Cardiology, over 2000 adults aged 51 to 80 were assessed by the SRT over a follow up period of about six years. Lower SRT scores out of 10 were strongly associated with higher all 'cause mortality, and a one point higher SRT score was linked with about a 21% reduction in mortality risk. That's a massive difference even after adjusting for age, sex and BMIA. Larger follow up study published in 2025 in the same journal expanded these findings in a cohort of over 4000 adults. It's actually harder than it looks crossing your legs and standing upright. Our team recently did a competition to see who could do it. And I have to say, without a punch on the floor from my fist, I found it really hard to get up in one movement. Although others on our team, Marissa back there was able to do it very easily. Whereas the other two guys here, Andrew and Rajiv found it pretty hard. So the take away here is, is simple. Real world function predicts your long term survival. So fitness, it's not just about how fast you can run, how long you can run, how good you look. It's about your capacity, your ability to move through life for much longer. Consistency Beats Extremes: Racket Sports Longevity People often ask me what type of exercise they should prioritize, and my honest answer is should build variety first, Develop baseline competence across endurance, strength, power, balance, and mobility. But consistency matters much more than intensity. Enjoyment also matters, and that's even more important than optimizing 1 paradigm. The goal is not perfection. It's about participation repeated over years. It takes decades sometimes to see the ultimate benefits of movement so you can improve all of these aspects of fitness from certain sports. There are two large studies that have found that racket sports, especially tennis, are associated with some of the longest lives. This is certainly my experience with people that I know in their 70s, eighties and even their 90s. It all started with a 2016 study in the British Journal of Sports Medicine, which followed more than 80,000 adults in the UK. And it found that people who played racket sports like tennis, badminton and squash had a 47% lower risk of dying from any cause. Compared with activities like running, cycling, swimming, soccer, even aerobics, these racket sports came out on top. Then in 2018, a long term study published in Mayo Clinic Proceedings tracked over 8 1/2 thousand adults in Copenhagen for nearly 25 years. Playing tennis again was associated with almost a 10 year increase in life expectancy compared with being sedentary. Other activities helped too, but none matched tennis. Badminton about six years, soccer nearly five years, cycling and swimming, which we often think are some of the best, around 3 to 4 years, and gym based cardio was closer to one to two years. One of the authors of that study, cardiologist Doctor James O'Keefe, put it bluntly. Calling tennis the world's healthiest sport is actually very defensible. Scientifically, he argues, the data for tennis is stronger than for any other sport. In his words, it's not BS. We have to be careful here though about cause and effect. Tennis is played by people generally with greater income, which is known to track with longevity. And in these two studies I just mentioned, basketball was not even in the list. So how much is enough exercise? A fascinating follow up study from the same Copenhagen group has challenged the idea that more exercise is always better. Doctor Jacob Marrat and his team followed nearly 9000 healthy adults for over 25 years, and they looked at how the amount of weekly sports activity related to longevity. What they found was a clear U-shaped relationship between exercise and mortality. So the people who did no sport, of course, has significantly higher risk of death. We expect that this isn't surprising, but what caught my attention was the other end of the curve. Those doing very high volumes of sport more than 10 hours a week also had higher risk of death compared to people who exercised moderately. The lowest risk of dying from both cardio and all causes was seen in people who exercised about 2 1/2 to 4 1/2 hours per week. In other words, the sweet spot wasn't extreme training or endurance obsession, It was regular, moderate participation in sports. This pattern held up even after adjusting for age, sex, smoking, alcohol, body weight, blood pressure, cholesterol and a bunch of other things. It also persisted when the first five years of follow up were excluded, suggesting that the results weren't simply due to pre-existing illnesses. The take away here is super important. Exercise is definitely a powerful medicine, but like most medicines, dose matters. Pushing the body relentlessly may blunt some of the longevity benefits that we associate with physical activity, and this study supports the idea that for long term health and for longevity, consistency beats extremes and recovery is just as important as movement. Minimum Guidelines and Daily Movement Benefits So how much exercise should you be getting every week? Well, the current guidelines are at least 150 minutes per week of moderate intensity aerobic activity or 75 minutes of vigorous activity, or a combination of the two, spread across the entire week. Hitting this minimum is associated with roughly a 14% reduction in all 'cause mortality. Importantly, the benefits begin well below that threshold. Just 75 minutes per week of moderate activity, which is only about 11 minutes per day, is associated with a meaningful reduction in the risk of premature death and cardiovascular disease. So moving from nothing to just something delivers a large return on investment. And again, these large cohort studies consistently show a dose response relationship. More activity generally confers more benefit, but only up to a point. The largest gains are between 5:00 and 10:00 hours per week of moderate activity. So that's mortality risk. But what about aging? Well, analysis of national data sets with millions of people show that those who accumulate around 3 hours of activity per week, not a lot, They have the lowest risk of accelerated biological ageing, but with diminishing returns beyond that range. There is no single optimal schedule though. But remember this adherence beats optimization. So let's talk about sitting. It's a serious matter because most of us for our jobs have to sit for some of the day. And the problem is exercise does not fully offset prolonged sitting, Regular movement throughout the day, standing up, walking, any brief activity breaks, adds independent benefits beyond these structured workouts when you go to the gym or play a sport. So get a standing desk, one that you can lift up and down during the day. That's what I have in my office. And at home, you can get a small treadmill. I have one in my living room and I open it up. And even preparing for this podcast, I was. Speaker 2 Walking while reading. One thing I've learned after decades of studying aging is that you simply can't consistently improve anything that you don't measure. A few months ago, after a lot of travel and speaking engagements and probably too many dinners out, I realized I'd put on a few extra pounds and I could see the graph on my withing scale, and I needed to shed a few. My goal, however, was not to simply lose weight. I wanted to get back to my usual body composition. Had I lost muscle? Was my visceral fat creeping up? What did I need to focus on? That's why I like the Withings Body Scan scale. It tells me much more than my weight. It measures body fat, muscle mass, visceral fat, and even includes an FDA cleared ECG. As I made a few changes to my diet and got back into my normal routine, I could actually watch my body fat come down while preserving my muscle. And that's far more useful than watching a single number on a scale. I've actually been using Withings products for well over 10 years, and lately I've become a big fan of their watches as well. They continuously track heart rate, sleep activity, temperature trends, and even blood oxygen. I wear the Withings Silver Scan Watch Nova, which looks a lot like an expensive diving watch, and my partner Serena wears one of the slim gold models. She loves that it looks like an elegant watch first and a health tracker second. Withings also makes one of my favorite blood pressure monitors for home use. Also, a sleep analyzer that can help identify sleep issues and have a smart thermometer as well. To me, that's what longevity is all about. Measuring what matters, making small improvements, and letting those improvements compound over the years. Withings makes it easy to build your own health home lab. So whether you're tracking your body composition, blood pressure, sleep, heart health, or activity, you'll have the data you need to understand whether the choices you're making are actually improving your health or even harming them. If you'd like to build your own health home lab like I have, visit withings.com/lifespan and use the code LIFESPAN to receive 10% off. Speaker 1 For children and adolescents, the bar is higher, though at least one hour per day of moderate to vigorous activities supports musculoskeletal development, metabolic health, and long term habits. For older adults, it's also never too late to start. Even people in their 80s and beyond that show improvements in aerobic capacity and strength even after short training interventions. Biology responds to stimulus at any age. The central message here is really simple. Do enough to matter and just keep doing it. Longevity is built through accumulation. Start where you are, progress gradually, stay consistent. Your body will reward you. VO2 Max: Strongest Predictor of Longevity So now let's talk about cardio respiratory fitness, the strongest predictor of longevity. If I had to pick one physical attribute that best predicts longevity, it would be cardio respiratory fitness. Not body weight, not cholesterol, not blood pressure. Epigenetic clocks that incorporate fitness metrics show younger biological age in individuals with greater fitness. Cardio respiratory fitness reflects how well your heart, your lungs, blood vessels and muscles work together to deliver and use oxygen during sustained effort. It integrates multiple systems into a single functional outcome. The gold standard metric for cardio respiratory fitness is the VO2 Max, the maximum amount of oxygen your body can use during intense exercise. It's a direct window into whole body physiological capacity. V stands for volume, O2 is for oxygen, and Max means maximum. VO2 Max is grounded in the thick principle cardiac output multiplied by the arteriovenous oxygen difference. In plain terms, it reflects how much blood your heart can pump and how efficiently your muscles extract oxygen from it. This is why elite endurance athletes sit at the top of the VO2 Max distribution. Their hearts pump large volumes of blood, their hemoglobin carries a lot of oxygen, and their capillary networks are dense. Their mitochondria are also highly trained. Without regular training, though, VO2 Max declines roughly 10% per decade starting in early adulthood, and by age 70, the decline even accelerates. This loss reflects reductions in the maximum heart rate, stroke volume, and peripheral oxygen extraction. With consistent training, though, that decline can be cut roughly in half. Fitness does not eliminate aging, of course, but it can meaningfully slow this functional decline. This matters because low cardio respiratory fitness is one of the strongest predictors of all 'cause mortality that we have across multiple large studies of people. Those in the lowest fitness percentiles have 4:00 to 5:00 fold higher risk of death compared to those in the highest percentiles. A very large study published in 2018 in the Journal of the American Medical Association involved over 120,000 people and they looked at their cardio respiratory fitness using treadmill tests, which is essentially A proxy for VO2 Max. What they found was that the fitter you are, the lower your risk of death, with actually no upper limit for where the benefit disappeared. When compared side by side, low fitness predicted mortality more strongly than smoking, diabetes, hypertension. Importantly, improvements do not require elite performance. Just moving from low to moderate fitness produces the largest survival gains. And fitness also predicts outcomes late in life. In adults over 80, those with preserved aerobic capacity have dramatically lower mortality risk than their less fit peers. It's worth remembering that fitness is not a snapshot of what you did last week. It's an accumulated record of how consistently you've challenged your Physiology over years. VO2 Max is earned. You might wonder how VO2 Max is actually measured if you haven't done it before. Typically, you need a face mask or a mouthpiece, and that's required to directly measure oxygen consumption using indirect calorimetry. And this tracks how much oxygen you inhale and how much carbon dioxide you exhale breath by breath. Laboratory VO2 Max tests typically cost a few $100 and are not appropriate for everyone, especially those with underlying cardiovascular disease, and less medically supervised wearables can estimate VO2 Max using heart rate, pace, age, sex, and body weight. These estimates can be useful for tracking trends over time, but of course they're not precise measures of the true maximal oxygen uptake. There are also protocols like the Six minute walk, the 12 minute Cooper movement test, step tests which estimate aerobic capacity without requiring maximal exertion. These methods trade precision for accessibility. So the Cooper test is how far you can run or walk in 12 minutes. Very simple. And it's inventor Kenneth Cooper is one of those people who quietly changed how the world thinks about health. He was the one that literally coined the term aerobics in the 1960s. His book aerobics helped move exercise from something just athletes did to something medicine can prescribe. I had the distinct pleasure of meeting Mr. Cooper a few years ago, and it was really striking to meet someone whose ideas have influenced millions of people. And now he's 94, so obviously something's working. So if you don't want to use a device, prediction equations based on age, resting heart rate, body composition and activity habits can still provide a reasonable approximation. What matters most is not the exact number, but the trend. Improving fitness over time, even modestly, is strongly associated with better health outcomes. Fitness also interacts with strength, and people often ask which matters more. The answer actually is both. Studies comparing grip strength and cardio respiratory fitness show consistently that higher aerobic fitness lowers mortality risk across all strength categories. Strength matters, but fitness often carries more weight. That said, strength independently predicts survival and functional independence. The greatest protection comes from combining aerobic fitness and muscular strength. Resting Heart Rate, Recovery, and HRV Insights So now let's talk about heart based metrics. Beyond VO2 Max, several simple heart based measures can reveal a great deal about health and aging. They're easy to track, inexpensive, and strongly predictive. Resting heart rate is the number of beats per minute when you're fully at rest. For most adults, it's between 60 to 80 beats a minute, but physically fit individuals often sit lower, sometimes in the 40s or the 50s. My awake average is 67, and it goes down to 57 at night. A lower resting heart rate generally reflects higher stroke volume of the heart. Better capillary health and better autonomic balance. Your body's ability to shift smoothly between stress mode and recovery mode. A higher resting heart rate is independently associated with higher risk of all 'cause mortality. For every 10 beat per minute increase, it's associated with roughly a 15 to 20% increase in risk. Your resting heart rate is influenced by many factors. Your genetics, fitness, how much sleep you've had the night before, your stress level, even your hydration and of course illness, medications, caffeine and even the ambient temperature can matter. But what matters most is the trend over time, not your day-to-day noise. So you might be wondering, what if I naturally have a low resting heart rate even without exercise? And the answer there is intriguing. It turns out that those who don't even exercise and have a low resting heart rate tend to live longer. There is just some people with a naturally slow resting heart rate. They're born with a high vagal tone. They're the lucky ones. But for most of us, we have to work a little harder. And sometimes people say, well, do we just get a certain number of heartbeats in our lifetime? And is exercise going to affect that, reducing how long I live? And that's actually not true. The number of heartbeats doesn't determine how long you live. And in fact, if you compare a rat and a bat that have roughly the same kind of heartbeat, a rat lives about three to four years and a bat can live 30. So that really doesn't hold. But in general, species that have slower heart rates do live longer, but not because of the heartbeats, it's because that's just their general Physiology. But importantly, despite transient increases during your workouts where your heart rate goes up, habitual exercise lowers your average heart rate. Fit individuals accumulate fewer total heartbeats per day than sedentary people. This is a sign of greater cardiovascular efficiency. Another variable is heart rate recovery, which measures how quickly your heart rate drops after exercise. It reflects parasympathetic reactivation, the body's ability to shift from stress back to recovery. A drop of 20 beats per minute or more in the first minute after exercise is generally considered healthy. Slower recovery is associated with higher risk of cardiovascular events and mortality. Heart rate recovery actually gets worse with overtraining as well as illness or chronic stress. It functions as both a fitness metric and an early warning signal. So now for heart rate variability, one of my favourites, HRV is one of the better measures of cardiovascular fitness. Speaker 2 Most people assume a healthy heart beats like a perfect metronome. It doesn't. In fact, a healthy heart actually shows quite a lot of variation, and that's a healthy thing. That's what heart rate variability, or HRV, measures, the small differences in the time between each heartbeat. When your HRV drops below your normal baseline, your heart starts to behave more like a metronome. That usually means your fight or flight system is taking over. In other words, your body is under stress and it has less capacity to adapt. That can show up for a number of reasons. Psychological stress, poor sleep, illness, fatigue, even a heavy training load. So HRV can be useful as a check engine light for your recovery. You can measure it with most wearables these days. It's not a perfect measure, but it's really informative. Speaker 1 It's one of the things I look at most during the day, what matters most. Speaker 2 Here is the trend though, if you see a sustained drop of around 10 to 20% below your baseline, especially alongside a rising resting heart rate. Speaker 1 And worsening sleep, that's a signal that your body may need more recovery. In adults, normal HIV varies widely depending on age, sex, genetics, and how it's measured. There are two main ways to measure HRV. One is the RMSSD and the other is SDNN. So if you want to know, RMSSD is the root mean square of successive differences and then the other one is the standard deviation of normal to normal intervals. These are just two different ways of measuring HRV. The one that's. Speaker 2 Used by WOOP. One of Lifespan's partners is the RMSSD. RMSSD is the gold standard marker of parasympathetic recovery. Understanding the biology behind exercise is of course important, but having real time data about how your own body responds to exercise is essential for putting that science into practice everyday. Which brings me to a science based wearable that I'm particularly fond of, partly because of its scientific foundation at Harvard where I work, but also the founders own research and scientific rigor. Speaker 1 Of course I'm talking about the woop. Speaker 2 Band the one that I rarely take off. As a scientist, I like measuring things rather than guessing, and WOOP continuously tracks my sleep, my resting heart rate, my heart rate variability, respiratory rate, daily strain recovery and other aspects of my health, giving me objective data about how my body is responding to the changes that I make. On weekends, you'll usually find me on Cape Cod in my workshop or outside on the property planting fruit trees, repairing the house, or hauling lumber in my old 1992 Ford F-150 pickup. Sometimes, however, I wake up eager to get outside. But my WHOOP tells me a different story. My heart rate variability is lower than usual, my resting heart rate is elevated, and my recovery score is really poor. So on those days, I still head out, but I pace myself. I found that listening to those signals helps me recover better and work harder over the long term. I appreciate that Whoop is backed by great science. For example, in 2022, Miller and colleagues published a study in the journal Sensors comparing 6 leading wearable devices against clinical grade measurements of sleep, heart rate, and heart rate variability. WOP was among the most accurate for measuring overnight heart rate and HRV. These are the two biomarkers that I pay close attention to because they provide valuable insights into recovery and physiological resilience. So if you don't already use WOP, I really encourage you to give them a try. So visit join.woop.com/lifespan and you can use the code Lifespan to receive your free WOOP. Speaker 1 And your first month of membership. Typical adult values are between 20 and 50 milliseconds. For optimal health and longevity. Higher HRV relative to your own baseline is what matters most. So in general, people who are physically fit, sleep well, manage stress, and recover properly tend to sit above average for their age, between 40 and 70 milliseconds or higher. Though there's no single magic number, low HRV is associated with increased risk of cardiovascular disease, metabolic dysfunction, even cognitive decline, and of course, mortality. HRV tends to decline with age, but you can modify it. In fact, by exercising, sleeping well and managing stress, you can raise your HRV. It's very sensitive. You can go the other way as well, some alcohol. And if you don't sleep well, you're ill or you have stress. Even overtraining can reduce your HIV. And as with resting heart rate, trends matter more than isolated readings. We've talked about aerobic fitness, so now let's talk about muscle. Muscle as Endocrine Organ: Strength and Power Muscle's not just for movement. It's a metabolic, endocrine, and longevity tissue. Resistance training matters independently of aerobic fitness, so we need to focus on that too. Just one to two strength training sessions per week are associated with much lower mortality risk. Going far beyond that does not appear to add substantial longevity benefits at the population level at least. So what do I mean by strength training? I mean squats or sit to stands, deadlifts, hip hinges, push ups or bench presses, rows or pull downs, these kind of things that build muscle. But what matters is progressive resistance, working the muscles against the load. Done consistently, just 30 to 60 minutes per session, even once or twice a week, is enough to preserve muscle bone insulin sensitivity and independence, which likely explains the longevity benefit. Muscle mass and strength decline with age, a process known as sarcopenia. This loss accelerates after midlife and contributes to frailty, loss of independence, metabolic dysfunction, and increased mortality. One of the simplest ways to assess your muscular health is grip strength. It's an imperfect proxy, but remarkably predictive. Lower grip strength is consistently associated with higher risk of death, cardiovascular disease, disability, and even cognitive decline. One of the measures of longevity and age reversal in my lab is grip strength. We do it with the mice. They have to hang on to a little mesh, and we see how hard and how long they can hold on for. It's very predictive, not just how healthy they are and strong they are right now, but how long they're going to live ultimately. Grip strength typically peaks in early adulthood and declines steadily thereafter. The rate of decline accelerates after about age 70, particularly in the absence of resistance training. Yet every additional kilogram of grip strength is associated with a meaningful reduction in mortality risk, probably because the hand is a bellwether, like a Canary in the coal mine, representing your overall fitness. So why do we get weaker? We take it for granted, but there are a lot of reasons for it. Not just muscle shrinkage, but even the nerves, they fire less and they make less contact with the muscles. These motor neurons that contact the muscle retract, and this is actually something we're trying to reverse in my lab. There's also hormonal changes, growth hormone declines and testosterone, both of which are important to maintain muscle mass. But strength alone, of course, is not the whole story. Muscle power, the ability to generate force quickly, declines earlier and faster than strength, and this loss strongly predicts falls, fractures, and loss of functional independence. Starting around age 40, we lose about 0.5 to 1% of muscle mass and strength per year. And that's why you've probably heard that doing resistance training and eating enough protein even well into your later years is important. But here on this graph that we're showing, we can see that after 40, we lose around 2 to 4% of muscle power per year. That's due to motor neuron loss and denervation, as I mentioned, the retraction of nerves out of the muscle. It's also due to a preferential atrophy of what are called fast twitch or type 2 fibers in the muscle catching yourself when you trip or standing up from the floor reacting to a sudden loss of balance. These are tasks that depend much more on power than on maximal strength. Studies suggest that muscle power may be a stronger predictor of mortality than muscle strength alone. Preserving power is therefore central to healthy ageing. One of my colleagues at Harvard once said the secret to longevity is hanging onto the handrail. And what he meant by that is falling is so damaging to older people, especially in their 80s and 90s. One full and a broken bone can send you into the operating theatre. You can lose oxygen to the brain and most people over 90 never fully recover. The good news is that muscle responds to training at any age. So just as a reminder, power is the ability of a muscle to generate force quickly. In physics terms, power is force times velocity. So power can be gained safely by doing a variety of things. Sit to stands, step UPS and even medicine ball throws. So if you only train for strength and ignore power, you're missing a major piece of the healthy ageing puzzle. Another important reason for exercising is because muscle is an endocrine organ. Contracting muscle releases myokines that influence metabolism, inflammation, brain health and immune function. But a common misconception is that there is a narrow window early in life when physical activity matters, and that once it closes the benefits are largely lost. That's absolutely not true. The evidence doesn't support this view. Muscle loss during ageing is not inevitable. In many cases it's simply disuse. Muscle stays young if it is used. Remember that regular movement early in life does build capacity and establishes habits that carry forward. But starting later, even at 90 and 100, is known to produce meaningful gains. Biology remains responsive to stimuli well into advanced ages. Researchers who have studied sedentary octogenarians so people are in their 80s, have found large improvements in aerobic capacity and workload tolerance even after only a few weeks of training. And while these gains in older people generally fade faster than in younger individuals if they stop training, this simply reinforces the central rule. Consistency matters more than intensity. Exercise also improves resilience during illness and recovery. Older adults who remain active recover faster from hospitalization, surgery and acute illnesses than their sedentary peers. One of my favorite studies comes from Aging Cell, led by Able Plaza Florido with collaborators across UC Irvine, Copenhagen University Hospital and London University. Published in 2025, the researchers studied people aged 100 to 104, and they asked a simple question. Does movement still matter that late in life? The answer was a resounding yes. After just a brief bout of physical activity, centenarians showed a measurable drop in inflammatory proteins and the activation of protective immune and stress response pathways that were largely silent at rest. What's remarkable is that these were not lifelong athletes, yet their cells still woke up when they moved. It's a powerful reminder that even at extreme ages, the body retains the machinery to respond to exercise. Movement doesn't just maintain health, it actively flips protective molecular switches right up into advanced ages. The take away is straightforward. There is no expiration date on adaptation, and the body does not need perfection, it needs stimulus. So start where you are, progress gradually, and repeat. Movement Reshapes DNA Methylation and Epigenetics So we've covered what happens at the physiological level, so now let's look at the molecular to see what's really happening. Exercise influences nearly every hallmark of aging through a coordinated set of molecular and cellular responses. Mitochondria are central to this process. Regular movement and exercise increases mitochondrial number and efficiency. Pathways involving AMP kinase, PGC 1A, and SERT one, the gene we study in my lab, become activated, improving energy production and metabolic flexibility. Exercise also promotes autophagy, as you know, the cellular recycling system that clears damaged proteins. Single bouts of resistance exercise. Weight training transiently suppress autophagy to prioritize muscle growth, but repeated training actually increases the baseline autophagic capacity over time. Endurance exercise appears to activate autophagy across multiple tissues, though long term human data are still really emerging. Exercise also mobilizes stem cells and it improves proteostasis, which is the maintenance of proteins and it enhances stress response pathways that maintain tissue and function as we get older. At the epigenetic level, physical activity reshapes DNA methylation as well as histone modifications and non coding RNA profiles in a direction opposite to that of age-related drift, the process that we study in my lab. So trained tissues consistently show a more youthful molecular signature. These effects are observed across muscle and blood and brain, liver and even adipose tissue or fat. So exercise doesn't just target one organ, it coordinates the whole system, slowing and even reversing aspects of ageing. So while we're on the topic of epigenetics, let's talk about epigenetic clocks. As you probably know, they can estimate biological age by measuring DNA methylation patterns that change predictably with age. Multiple independent clocks now exist, each one trained on different outcomes such as mortality, disease risk or physiological decline. At the epigenetic level, the level where we're talking about gene regulation, exercise doesn't just slow ageing, it actively pushes biology in the opposite direction. Across large population studies, higher physical activity and higher cardio respiratory fitness are both associated with younger epigenetic ages. This relationship holds across multiple clocks, including ones called grim age, pheno age, and the Dunedin Poem clock. For example, a 2023 scientific paper in the journal Aging Cell that studied over 3 1/2 thousand adults in Germany showed that higher physical activity, including more steps and greater energy expenditure, is associated with lower grim age and pheno age rates of change. This might occur partly by lowering cardiovascular risk, but also by counteracting something called immunosenescence, a term referring to how our immune system ages and gradually becomes slower, less responsive, and also more prone to chronic inflammation. Importantly, the association between movement and clocks is dose dependent. Moderate to vigorous activity shows stronger links to slower epigenetic aging than light activity alone. In this case, your effort matters. My good friend Steve Horvath has co-authored several studies showing that higher physical fitness is associated with younger biological age. Based on specialized ageing indicators like DN, AM fit age which incorporates metrics like VO2 Max, walking speed and grip strength. Highly active individuals can be between 1 1/2 and two years biologically younger than their sedentary peers, even though other lifestyle factors like smoking and diet can play a role. In longitudinal studies, individuals who remain active over years show slower biological age acceleration than those who become sedentary. Even recent activity matters. The system responds dynamically, and data from elite athletes show that long term physical activity is also linked to slower biological ageing. For instance, a 2024 study of over 400 Hungarian. Speaker 2 Athletes. Speaker 1 Found that athletes had lower rates of biological ageing. This aligns with data from US Olympians, who live about 5.1 years longer than the general population. It's important, of course, to note that Olympians differ from the general population in in many ways beyond just exercise, so the longevity gap can't be attributed only to physical activity. Still, when researchers looked at Hungarian Olympic champions, they found that they had slower epigenetic ageing rates compared to non champions, which is really interesting. And when scientists look directly at human muscle itself, they see the same thing. A 2023 meta analysis looking at over 3000 human skeletal muscle samples. Speaker 2 They reported that higher. Speaker 1 Aerobic fitness was linked to younger epigenetic and gene regulation profiles. Essentially, exercise training shifts the muscle towards a more youthful molecular state, while muscle disuse actually ages the cells. And since gene regulation is one of the cells biomarkers of ageing, this suggests that staying fit helps your muscles preserve their youth. These clocks are not perfect, of course, they're statistical models. But when independent clocks all point in the same direction, we can increase our confidence. So ageing pulls the epigenome towards disorder, as we've shown in my lab. But movement, exercise, training, these all reliably pull them back. They restore the epigenome to a more youthful state and the net effect is preserved function and less chance of disease in later years. Exercise for Immunity, Brain, and Metabolic Health So how about the effects on immune function and inflammation? Meta analysis, the so-called study of other studies. These have shown a consistent anti-inflammatory adaptation with regular training. Acute exercise actually increases inflammatory signals and sometimes we see that with spikes in cortisol for example. But chronic training lowers baseline inflammation and reduces age-related inflammation, which is important for longevity. Acute exercise has been shown in many studies to mobilize immune cells, particularly natural killer cells and cytotoxic T cells, which are required to keep cancer cells at Bay. And a new study of older adults from 2025 showed that long term endurance training led to an increase in natural killer cell activity. The key nuance is dose. Moderate, consistent training improves immune readiness, while excessive training without adequate recovery can at least transiently impair certain immune parameters, which is one reason periodization and recovery are really important. Physical activity is one of the most powerful interventions we have for the brain as well. Its effects extend from mood and cognition all the way to long term protection against neurodegenerative diseases like Alzheimer's. Regular movement improves attention in the short run as well as your processing speed and executive function, and these benefits appear across your lifespan and are observed both in observational studies and controlled intervention studies. Exercise increases the level of rain derived neurotrophic factor or BDNF. This growth factor supports synaptic plasticity, neural survival, and learning. Higher BDNF is consistently associated with better cognitive performance, and in rodents, exercise robustly stimulates what's called hippocampal neurogenesis, or the growth of new nerve cells in the hippocampus. Hippocampus is the part of the brain where we store and process memories, and in humans, direct measurement is much more difficult. But structural and functional imaging studies support improved hippocampal integrity with regular aerobic activities. As we get older, we tend to lose blood flow not just in our muscles but also in our brains. And the good news is that physical activity is known to improve cerebral blood flow, enhancing the delivery of oxygen and nutrients to brain tissue. This vascular contribution likely underpins at least part of exercises protective effect against cognitive decline as we get older. Mental health benefits are substantial with exercise. It reduces symptoms of depression and anxiety, and it's comparable to first line therapeutics for mild to moderate depression. And that's been shown in many, many studies. These effects are not just limited to intense training. Even moderate exercise and consistent activity is sufficient to produce meaningful improvements in mood. What science is showing is that exercise, even late in life, can slow neurodegeneration, either by reducing inflammation, improving blood flow in the brain, and activating neurotrophic pathways that stimulate new nerve growth. A large prospective cohort study published in 2019 followed older adults for over a decade and they found that higher levels of physical activity were associated with a significantly lower risk of dementia, even after accounting for genetics and vascular risk. This work aligns with more mechanistic studies showing that exercise is associated with lower circulating neurodegeneration markers, including neurofilament light chain. The take home message is optimistic. Starting earlier appears to confer the greatest protection, but the brain does remain plastic even in older ages. As we all know, exercise is also good for sleep, so regular movement improves not just your sleep quality but your circadian regulation, which in turn supports memory consolidation and even emotional regulation. So now let's talk about metabolic health. Metabolic dysfunction sits at the centre of many age-related diseases and physical activity is one of the most effective ways to preserve metabolic health across our life spans. Exercise improves insulin sensitivity by increasing glucose uptake into muscle through insulin dependent and insulin independent pathways. Glute 4 is a transporter that goes to the outside of cells to suck the glucose out of the bloodstream and contracting muscle acts as a powerful glucose sink. A single bout of exercise improves glucose control for hours and repeated bouts produce durable improvements in insulin sensitivity, which is what we need for long term health and also glycemic regulation. And importantly, physical activity also reduces the amount of visceral fat, the kind of very dangerous fat that lines your organs that you can't really see on the outside. Lipid metabolism improves as well with regular movement. Exercise can raise HDL cholesterol, the good type, lower triglycerides and even improve lipid particle size and function, contributing to reduced atherosclerotic risk. Exercise also reduces the risk of metabolic associated fatty liver disease, and it improves hepatic insulin sensitivity. Importantly, many metabolic benefits arise independent of weight change, so fitness modifies risk even when body weight remains stable. So we've talked a lot about how exercise can make your brain and your body healthier for longer. But what about your skin? Exercise Benefits Skin, Tissues, and Overall Longevity It turns out that movement effects tissues that we don't typically associate with exercise. In a randomized clinical trial published in 2023 in Scientific Reports, a study of middle-aged sedentary women compared aerobic training and resistance training over 16 weeks and they found improvements in skin elasticity and upper dermal structure in both groups. Resistance training uniquely increased dermal thickness and it was also linked to increased dermal by glycan, which is involved in maintaining skin structure. Regular exercise is associated with increased cutaneous blood flow too, so it's not just the brain and the muscle. Your skin gets more blood as well. Connective tissues also respond to exercise. Tendons and ligaments strengthen. This supports joint integrity and reduces injury risk. Disuse has the opposite effect, reduced collagen turnover, greater stiffness and higher risk of strain. I was surprised to learn that about 30% of adults after the age of 40 have some form of rotated cuff tear, and this can rise much higher with increasing age. In my experience, almost half the men that I talked to have shoulder problems. So you've got to keep moving and maintain the strength of your shoulders. So the principle here is really simple. Structure follows function. Tissues that are used are maintained. Use them or lose them. We've covered a lot in this episode. We've looked at the evolution, the Physiology, the molecular biology, and even population data, and the central message is super simple. Humans evolved to move. Our biology expects it. When movement disappears, systems drift out of calibration. We age more rapidly. But when movement returns, many of those systems realign. Physical activity is not a single intervention of course, it's a systems level signal. It engages the cardiovascular system, skeletal muscle, immune function, metabolism, brain health, skin and connective tissue. It's difficult to find another behaviour that we can do that touches as many longevity pathways at once. Exercise slows functional decline. It preserves capacity and compresses morbidity. More years of life spent capable, independent and engaged, and maybe even better looking. The evidence is strongest for cardio, respiratory fitness and muscular strength and power. These are not abstract metrics. They translate directly in how we live day-to-day. The benefits are not reserved for athletes. The largest gains occur when people move from inactivity to modest, consistent movement. It's also never too late. Adaptation persists into advanced age. The biology does not close its doors. The take away is this. Movement and exercise are not optional for healthy ageing and longevity. They're foundational, and unlike most interventions, they remain available to nearly everybody every day. Join Lifespan.com and Support Research It's been great to have you with us. This is a. Speaker 3 Show where science and evidence come first. The team works hundreds of hours to bring you only the facts. To learn more and to join our community, visit lifespan.com and you'll get early access to future episodes to the Lifespan Magazine and to detailed episode show notes. You also get transcripts and links to papers that we talked about today. As a member, you'll actually be helping us support medical research to extend all of our healthy lives. If you found this episode valuable, do consider subscribing and also turn on your notifications so you don't miss new episodes. It'll also help us make a better show for you. And feel free to share this episode with any family or friends who you think might enjoy it and learn from it. Finally, for the latest discoveries in longevity science, consider following us on Instagram at Lifespan and on X at Join Lifespan. From all of us at Lifespan, thank you for being part of this growing community. And remember, life's short. So let's change that together. Lifespan is produced by Andrew the wonder Man Ying Rajiv, geek me out. Ramesh, Marissa, who's on 1st Vulgamore, Kathleen, TLDR Fitzgerald and our researchers. Shivani. Just one more thing, Sethi and Nadeeb meet me in the year 3000. Johnson. Also, I want to mention our new recruit, Daniel Rocket Man Salazar, who's our new producer, and of course, Serena, my honeypoon. I also want to thank Inspiro Studio and create APE for making this show possible. And finally, thanks to our partners for helping us support longevity research. We'll see you next time. Speaker 1 This show is for informational purposes only and is not medical advice. Please consult A qualified healthcare provider as individual results may vary. Views expressed on my own and not those of Harvard University or Harvard Medical School. Full disclaimer is in the show notes.