Why Muscle Is the Overlooked Key to Longevity, Health, and Metabolic Function

Welcome back to The Young Lab, where we break down the science behind internal health, performance, and regenerative longevity. In today’s episode, we’re tackling one of the most overlooked, yet absolutely essential, predictors of lifelong health and vitality: muscle.

You probably think of muscle in terms of strength or looks, but as Dr. Young reveals, muscle is so much more. It’s the body’s central metabolic engine, governing how you manage glucose, regulate inflammation, support brain function, and even how you age. We’ll explore why muscle mass and strength are tightly linked to longevity, what happens as we lose muscle with age, and why focusing on weight alone can be misleading. We’ll also get into practical, evidence-backed strategies: the best ways to train, fuel, and recover for long-term muscle health and why balancing strength and cardio matters at every age.

Whether you’re a lifelong athlete or just starting out, this episode arms you with the frameworks and science to build resilience and protect your future health. Stay tuned!

Timestamps:

00:00 Understanding elevated glucose risks

04:49 Understanding muscle health and fat metabolism

09:22 Understanding glucose metabolism

12:32 Exercise and muscle metabolism benefits

15:28 Understanding anabolic resistance

19:53 Flaws of weight as a health metric

22:26 Focusing on body composition

26:20 Understanding body composition and risk

29:19 Calculating heart rate zones

33:22 Importance of daily protein intake

34:23 Optimizing protein intake strategies

40:01 Importance of recovery and balance

41:06 Effects of weight loss on muscles

46:39 Understanding zone two training basics

49:19 Balancing Training and Recovery

51:44 Looking forward to next episode

Show Website - https://theyounglab.com/

Dr. Michael Young's Clinic - http://denverwellnessaesthetic.com/

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Media Partner - https://www.tophealth.care/

“Disclaimer: Informational only. Not medical advice. Consult your doctor for guidance.”

Transcript

SPEAKER_01 0:00

When we hear people talk about muscle or how they think about it, they think about how they look or how much they can lift or their performance. But physiologically, muscle is one of the most important organs in the body. Muscle isn't just something on your body, it's actively regulating your entire physiology. Less muscle leads to worse glucose control, worse metabolism leads to more fat gain. More fat leads to more inflammation, more inflammation leads to further muscle loss. And this is how aging accelerates biologically. We don't just age because time passes, we age faster when we lose muscle. It's no longer just about losing weight, it's about preserving and building muscle because that is what protects your future health.

SPEAKER_00 1:22

So I know that this is a super important episode, and it's great to see you again, Dr. Young, as always. How are you? Are you excited for this episode?

SPEAKER_02 1:29

I am so excited for this one. This is gonna be a great episode.

SPEAKER_00 1:32

Absolutely. And I think muscle is often overlooked. We talk about it a lot, but it's usually not really from a physiological standpoint. So let's hop into that. So I know you often say that muscle isn't about strength or appearance, which is what we generally tend to associate it with, right? But it's actually one of the most important organs for long-term health. So when people think about muscle, they often associate it with fitness or aesthetics. But physiologically, why does muscle play such a critical role in health span and survival?

SPEAKER_01 2:02

Yeah, I mean, that's uh a really important question because most people have never been taught to think about muscle in this way. I mean, when we hear people uh talk about muscle or how they think about it, they think about how they look or how much they can lift or their performance. But physiologically, muscle is one of the most important organs in the body. And I use that word intentionally because muscle isn't just about helping you move, it's regulating your metabolism, it's controlling your blood sugar, it's controlling your energy production, your inflammation, and even how your body ages. So let's start with the most fundamental uh role of muscle, and that is it's your primary metabolic engine. So after you eat, especially carbohydrates, about 70 to 80 percent of the glucose is taken up by the skeletal muscle. So muscle is the main place your body clears glucose from the bloodstream, stores it as glycogen, and determines how much insulin is needed. Now, this is where it becomes really important for people to understand. Why does elevated glucose matter? Um, glucose itself isn't bad, but when it stays elevated chronically, it begins to damage the blood vessels. It increases oxidative stress and it leads to something called glycation. Glycation is where glucose binds to a protein or fat, forming what's called advanced glycation end products or ages. Um, the way you can think of it is that adding a glucose molecule to a protein or fat is like when we brown or caramelize food. So that adds that sugar, but it disrupts the structure and the nature of the proteins and the fats, which for food is great. Um, it's great tasting, but for inside our body, it's not ideal. So these ages they contribute to vascular damage, um, stiffness of the arteries, and accelerated aging. So chronically elevated glucose also forces the body to produce more insulin, and over time that leads to hyperinsulinemia and insulin resistance. Insulin resistance is not just about diabetes, it's strongly associated with cardiovascular disease, fatty liver disease, Alzheimer's disease, and many cancers. So when muscle is healthy, it protects you from all of that. When muscle is lost or dysfunctional, you lose that protection. Now, let's take this one step further because muscle also determines how your body uses fuel. Muscle is where you decide whether you are burning carbohydrates or burning fat. And this is what we call metabolic flexibility. When muscle is healthy, you can burn fat at rest and switch to carbohydrates when needed. When muscle is impaired or is dysfunctional, people become more dependent on carbohydrates. Um, fat oxidation or fat burning decreases and triglycerides begin to rise. And that's another important concept. Why are elevated triglycerides a problem? Well, triglycerides are a form of fat circulating in the bloodstream. And when they are elevated, they are often a marker of excess energy and insulin resistance. They contribute to fat accumulation in the liver, which we call fatty liver disease, and they increase the number of atherogenic or plaque-causing lipoprotein particles. And particularly these particles, uh, APOB or apolipoprotein B, can can penetrate the arterial wall where they become oxidized and contribute to plaque formation, inflammation, and atherosclerosis or hardening of the arteries. So elevated triglycerides are not just a number, they're a signal of poor metabolic health and increased cardiovascular risk. And again, muscle plays a central role in regulating that system. Now, here's something that's that most people have never heard. Muscle is actually an endocrine organ. When muscle contracts, it releases signaling molecules called myokines. These act like hormones and communicate with the rest of the body. Some important examples of myochymes would be IL6, which helps improve glucose uptake and reduce inflammation, uh, irisin, which promotes conversion of white fat to a more metabolically active brown fat. And then there's BDNF or brain-derived neurotrophic factor, and this supports brain health, neuroplasticity and cognitive function. Neuroplasticity means that the the neurons are able to repair. And then there's myonectin, which helps regulate lipid metabolism. So when you exercise, your muscle is literally sending signals to improve your metabolism, reduce inflammation, and support brain function. So muscle isn't just something on your body, it's actively regulating your entire physiology. And when we look at outcomes, this becomes really clear. Muscle mass and strength are strongly associated with lower mortality, fewer hospitalizations, and better recovery from illness. And also it helps preserve independence. Even something as simple as grip strength is one of the strongest predictors of all-cause mortality and functional decline. And the reason is it reflects muscle health, neurologic function, and overall physiologic reserve because muscle also acts as a reserve system. During times of stress, such as illness, injury, or surgery, your body breaks muscle down to provide amino acids which help support the immune function and maintain survival. If you don't have enough muscle, you don't have enough reserve, and that directly impacts outcomes. So when I say muscle is one of the most important organs for longevity, what I mean is this it regulates the blood sugar, it determines how you use energy, it influences inflammation and brain health, and it gives your body the reserve it needs to survive stress. Muscle isn't just about strength, it's about how your entire body functions and how well it ages.

SPEAKER_00 8:31

That is so much that is so interesting. When people think about muscles, I know no one's really thinking about all of those different factors. You touched on this a little bit, but how does muscle influence metabolism, especially when it comes to insulin sensitivity and glucose regulation?

SPEAKER_01 8:47

Yeah, um, this really builds directly on what we were just talking about. If if muscle is the primary place your body handles glucose, then metabolism really comes down to what's happening inside the muscle. After you eat, carbohydrates are broken down into glucose. Glucose enters the bloodstream and then insulin is released. And insulin's job is pretty simple. It tells your muscle cells to take this glucose out of the bloodstream. So in healthy muscle, this works very efficiently. Insulin binds to the muscle cell and it triggers a signaling pathway. Uh, and it moves these uh these little tubules in on the cell wall called uh GLUT4 transporters. They get moved to the surface of the cell, and then you can think of um think of this activity as like doors opening up and glucose moves into the muscle and it gets used for energy or it gets stored as glycogen and your blood sugar comes down. But when muscle becomes less responsive, which is what happens with inactivity, loss of muscle, or uh metabolic dysfunction, those doors don't open as well. So when glucose stays elevated longer, insulin has to rise higher to compensate. And over time, the body becomes chronically hyper-insulinemic. And that's where things start to shift in a way that's not healthy because insulin or elevated insulin doesn't just affect glucose, it changes how your entire body handles energy. It pushes the body towards storing energy rather than burning it. It suppresses fat oxidation or fat burning, so you burn less fat and it increases triglyceride production in the liver. So now you start to see rising triglycerides, more fat stored in the liver, more visceral fat, that's the fat around the organs, and that's how metabolic disease begins to build. Now, this ties into something really important and something we measure clinically, which is what fuel your body is actually using. Your body is designed to be flexible. At rest, you should be primarily burning fat. When needed, like during exercise or after a meal, you can shift to carbohydrates. And once again, this is called metabolic flexibility. But when muscle doesn't function well, people get stuck. They become primarily carbohydrate burners, even at rest. And this is where it's important to understand why this is a problem. If you're constantly burning carbohydrates, you're more dependent on frequent food intake and your blood sugar tends to fluctuate more. And this is where it's important to understand why being a primary carbohydrate uh burner is a problem. So if you're consistently burning carbohydrates, you're more dependent on frequent food intake, your blood sugar tends to fluctuate more, insulin stays elevated more often, and fat burning stays suppressed. So instead of accessing stored energy, your body is constantly looking for incoming energy. So over time, that leads to energy crashes, increased hunger, more fat storage, and worsening insulin resistance. So being carb-dependent is not inherently bad in isolation, but being locked into it is a sign that the system isn't working properly. Now, this is where exercise becomes incredibly powerful because when muscles contract, it can take up glucose without needing insulin. That's really important to understand. So exercise actually allows the muscle cells to take in glucose without insulin. So even, and this occurs even in people who are insulin resistant, you know, exercise opens up those GLUT4 transponders and blood sugar can move into the muscle. Uh, I always, with a lot of our patients, we recommend that they actually perform some light exercise after eating, like such as walking for 10 to 15 minutes after meals, because this will open up those GLUT4 transponders and allow the glucose to enter. Um, and beyond that, exercise improves mitochondrial function, which allows the muscle to burn fat more efficiently and produce energy more effectively and restore that metabolic flexibility. So when you step back and look at all of this, muscle is doing much more than just handling glucose. It's determining how much insulin your body needs, it's determining whether you're storing or burning energy and how efficiently your mitochondria function and whether your metabolism is flexible or rigid. So if muscle is controlling metabolism at that level, then losing muscle over time isn't just about getting weaker. It's about fundamentally changing how your body handles energy.

SPEAKER_00 13:52

And with muscle, one of the biggest challenges of aging is sarcopenia, so which is a gradual loss of muscle mass. But why does this happen and why does it accelerate health decline as people get older?

SPEAKER_01 14:04

Yeah, and this is where the conversation about aging starts to come into focus. Because if muscle is doing everything we just talked about, regulating glucose, insulin, and metabolism, then losing it becomes a much bigger problem than most people realize. And as you mentioned, we call this loss of muscle sarcopenia. And sarco is a Greek word for muscle, and penia means loss. And so most people think of that as something that happens later in life, but actually it starts much earlier. Um, you can begin losing muscle in your 30s, and on average, people lose about 3 to 8% of muscle mass per decade, and with that rate accelerating after age 60. But what's even more important, strength declines faster than muscle size. And that matters because strength, not just mass, is one of the strongest predictors of outcomes. Large population studies have shown that lower muscle strength is associated with higher all-cause mortality, independent of age or even independent of body weight. So people may look the same externally, but internally their physiology is already declining. Now, why does this happen? It's not just one factor, it's a convergence of changes. As we age, anabolic hormones like testosterone, estrogen, growth hormone decline. So muscle becomes less responsive to protein and to training, which is called anabolic resistance. Mitochondrial function decreases, physical activity often declines, and chronic low-grade inflammation increases. So all of this shifts the body toward a more catabolic state, meaning it's breaking down tissue faster than it's building it. But here's where it becomes clinically important because this doesn't just stay isolated to muscle. So when you lose muscle, you lose your primary site of glucose disposal, which we've mentioned before. You know, muscle is responsible for the majority of glucose taken up after a meal. So with less muscle, blood glucose stays elevated longer, insulin levels rise, and that insulin resistance begins to develop. And chronically elevated insulin does something very specific. It drives fat storage, particularly in the liver. This is how we begin to see non-alcoholic fatty liver disease. So you get also a rising of triglycerides and an increased production of that APOB containing lipoproteins. And we mentioned before these apolipoproteins are important because they are the particles that can enter the arterial wall and contribute to atherosclerosis. So now muscle loss is directly contributing to cardiovascular disease, metabolic disease, and systemic inflammation. And at the same time, as insulin remains elevated and fat burning is suppressed, the body begins to accumulate more fat. And not just subcutaneous fat or the fat underneath your skin, but visceral fat, that fat that is around your organs. Visceral fat is highly metabolically active. It releases inflammatory messengers or cytokines like TNF alpha or IL-6, which worsen insulin resistance, increase oxidative stress, and promote further muscle breakdown. So now you have a reinforcing cycle. Less muscle leads to worse glucose control, worse metabolism leads to more fat gain, more fat leads to more inflammation, more inflammation leads to further muscle loss. And this is how aging accelerates biologically. This is also where we see something called sarcopenic obesity, which is low muscle mass combined with higher fat mass. And from a clinical standpoint, this carries one of the highest risks for mortality, higher than obesity alone, higher than low muscle alone, because now you have reduced metabolic capacity, increased inflammation, and impaired physiologic resilience. And that last part, resilience, is critical. Muscle acts as a metabolic and amino acid reserve. So during stress, illness, surgery, or hospitalization, your body breaks down muscle to provide amino acids to help the immune system function properly, support wound healing, and maintain essential processes. So individuals with low muscle mass recover more slowly, have higher complication rates, and have higher mortality in hospital settings. This is why studies consistently show that low muscle mass and low strength are associated with increased hospitalizations, disability, and mortality. So when we step back, sarcopenia is not just something that happens with aging. It's one of the primary drivers of metabolic decline, loss of function, and reduced survival. So we don't just age because time passes. We age faster when we lose muscle because we lose our ability to regulate metabolism, respond to stress, and maintain physiologic reserve. And once that is understood, it changes the goal. It's no longer just about losing weight, it's about preserving and building muscle because that is what protects your future health.

SPEAKER_00 19:40

And speaking about weight, I think many people, if not most people, really focus on weight as their main health metric. But why is muscle mass often a far better indicator of health and just the number on the scale?

SPEAKER_01 19:53

And so I don't blame people. I I blame our medical system because we, you know, that's how we've related or communicated it. Uh and you know, this is where a lot of people get misled because people are so focused on weight, but weight by itself is is a very poor measure of health. The scale tells you one thing, tells you total mass. I mean, yes, that includes your muscle, your fat, your water, your bone, um, but it doesn't tell you what your body is made of and where that weight is distributed and how it's affecting your metabolism. So you can have two people, excuse me, same weight, same height, and completely different health out outcomes or profiles. So one person may have higher muscle, lower visceral fat, and good metabolic health. The other person may have lower muscle, um, higher visceral fat and insulin resistance, same weight, very different physiology. And this is where BMI or body mass indexes really fall short. BMI is simply your height and your weight. Um, it doesn't account for muscle mass or fat distribution or metabolic health. So, in fact, studies estimate that a significant percentage of people with a normal body mass index are actually metabolically unhealthy. This is something referred to as TOFI, thin on the outside, fat on the inside, and that's TOFI, thin on the outside, fat on the inside. Uh, and these individuals are, they they look healthy, they have normal weight, but internally they have this higher visceral fat, they have lower muscle mass, and they have impaired metabolic function. And because they look healthy, they're often missed clinically. Now, on the other side, you can have individuals with a higher BMI who have more muscle. Um, have and with that more muscle, they have better metabolic health and they have a lower risk. So BMI alone or body mass and body mass index alone doesn't tell us who is actually healthy. The real issue comes down to body composition. Muscle and fat behave differently in the body. Muscle improves insulin sensitivity, it increases glucose intake, and it supports metabolism. It increases resting metabolic rate as well. Now, visceral fat is highly inflammatory. It releases cytokines, uh, it worsens insulin resistance, and it's strongly associated with cardiovascular disease. So the real question is not how much do you weigh, uh, it's how much muscle do you have and how much visceral fat are you carrying? Um, and this is why focusing on only weight can actually be misleading. Because if weight loss is not done correctly, um, you know, people often lose muscle and water along with some fat. Um, but most of the time it's muscle. And so when muscle is lost, metabolic rates decrease, insulin sensitivity worsens, and long-term weight regain becomes more likely. So someone may weigh less, but actually be less metabolically healthy. And we see this in in the clinic all the time, uh, particularly with the um weight loss uh medications we have available. So, you know, we try to get patients to focus more um on body composition instead of the scale. I mean, we want them to focus on their muscle mass, the fat distribution of the visceral fat, and also their strength. Because those metrics are actually which they actually predict metabolic health, your disease risk and longevity. So I guess to kind of summarize this this segment doesn't tell you how healthy you are. I mean your muscle does, body composition does, function does. And once that is understood and really stressed, you can stop chasing weight and and you can really improve your health.

SPEAKER_00 23:53

Absolutely. And when you do evaluate someone's longevity potential, what are the metrics related to muscle or fitness matter the most?

SPEAKER_01 24:01

Okay. Yeah, that's a great question. I mean, once um we understand how important muscle and metabolism are, the next step is how do we actually measure that? So in I'm I'm looking at a few key markers that consistently tell us how someone is functioning and how they're likely to age over time. And I really group these into three main areas cardiorespiratory fitness, strength, and muscle function, and body composition. Each one tells us something different about the body. So let's start with cardiorespiratory function or let's start with VO2max. So VO2 Max is essentially a measure of how much oxygen your body can use to produce energy. So clinically, it reflects how well your heart is pumping, how well your lungs are delivering oxygen, and how efficiently your cells, particularly your mitochondria, are using it. So when VO2 max is low, it tells us that the system as a whole has limited capacity. And that matters because with when stress increases, whether it's exercise or illness or aging, uh, those individuals reach their limits much, much faster. And that's why we consistently see that people in the lowest fitness levels have the highest risk of mortality. So one of the first goals is simply building capacity. Now, the second area is strength. And strength gives us a different type of information. It tells us about muscle quality, about neurologic function, and something very important: reserve. Reserve is your ability to handle stress. And so when something happens, uh like illness or injury, people with more strength tolerate it better, they recover faster, and they maintain independence. Um, that's why something as simple as grip strength, which we use, uh, has been shown to predict mortality, disability, and hospitalizations. Um, and it's not about the hand itself, it's about what it represents across the entire system. It's and it's extremely symbolic. Now, the third area uh is body composition. Uh, this tells us what the body is made of, how much muscle, how much fat, particularly visceral fat, and importantly, where that fat is located. Um, because as we mentioned in the last segment, because um, two people can weigh the same, but they can have very different risk profiles depending on that muscle mass and their visceral fat. And from a clinical standpoint, visceral fat is one of the strongest drivers of metabolic dysfunction, inflammation, uh, and cardiovascular risk. Uh, so body composition tells us what kind of mass someone is carrying, not just how much. Um, and once those three are understood, then we can go one level deeper if needed. Well, and we can look at things like resting metabolic rate, which is how much energy the body is using at baseline and fuel utilization, or whether the body is primarily burning fat or carbohydrates. And that helps us understand not just structure, but how the system is actually functioning. Now, when it comes down to targets, there's not one perfect number for everyone. But what we consistently see is that the highest risk is in the lowest categories: low fitness, low strength, low muscle mass. So the first goal is simple move out of the low, then gradually build capacity over time. Um, so when I'm evaluating someone, I'm not focused on their weight, as I stated earlier. I'm focused on how much capacity they have, how much reserve they have, and what their body is actually made of.

SPEAKER_00 27:52

And there's often a debate between strength training and cardiovascular training. So, from a good perspective, how do these two forms of exercise work together?

SPEAKER_01 28:02

I know it's based on the camp that you're in. I meant you have your die hearts in each one. Um, and I I like this debate. Um, strength versus cardio. Um, it's really there shouldn't be competition. Um, this is probably one of the biggest misconceptions because from a longevity standpoint, it's not either or, it's both. They each train different systems the body depends on over time. A useful way to frame this is exercise can be broken into three core components: resistance training, zone two cardiovascular training, and zone four or five high intensity training. Each one serves a distinct physiological purpose. So let's start with cardiovascular disease. So cardio is really about energy production and delivery. When we talk about zone two, um, the aerobic base, so when we talk about zone two, which is the aerobic base, this is where the body builds mitochondria, fat oxidation or fat burning, capillary density, metabolic efficiency, and this becomes the foundation of long-term health. So zone four or zone five, which is the high intensity capacity, this is where the body develops VO2 max, cardiac output, lactic tolerance. And this represents the upper limit of performance and resilience. So, how do you actually calculate these zones? Uh, a simple start, and everyone can use, and of course, there are some variations based on physical fitness. Um, but for most people, to get your max heart rate, you take 220 and subtract your age. Um, zone two is about 60 to 70 percent of your max heart rate, and then zone four or five is 85 to 95 percent of your max heart rate. Um, so to make it practical, zone two should feel sustainable. You should be able to hold a conversation. Zone four and five should feel like effortful. Um, breathing is heavy, and only a you can only speak a few words at a time. So, and for a simpler shortcut, zone two equals about 180 minus your age. This keeps most individuals in the correct uh aerobic range. Now, contrast that with resistance training. Resistance training targets a completely different system. Skeletal muscle is not just structural, it's an endocrine and metabolic organ, which we mentioned before. When resistance training is performed, most um the muscle fibers are recruited in stress. They repair and they remodel during recovery. This preserves lean muscle mass and improves insulin sensitivity. Muscle also, as we stated before, releases myokines, which influence brain health, inflammation, and metabolic health. And it also acts as a metabolic reservoir, um, helping regulate uh glucose handling or recovery from stress or long-term function. If one is missing, there's a cost. Cardia alone can lead to a loss of muscle, reduce metabolic reserve, strength training alone limits cardiovascular capacity, reduces physiologic efficiency. So, how they work together, cardia improves the ability to produce and deliver energy. Resistance training improves the ability to utilize energy and maintain structure. So this can be measured more precisely. I mean, there are tools like we use Pinoe, PNOE, which is a metabolic analyzer. It's possible with this tool to access oxygen utilization, carbon dioxide production, and fuel selections. This allows identification of efficient fat use at lower intensities or early reliance on carbohydrates. So, from a practical framework, a well-structured approach typically includes majority of cardio in zone two, strategic exposure to zone four and five, and consistent resistance, resistance training, and then of course adequate recovery. So the way to look at it, it's it's like building a high performance car, like a F1 engine or F1 car. The cardio is the engine, strength training is the frame, and intensity is the ability to accelerate. So if one piece is missing, the system does not perform the way it was designed to.

SPEAKER_00 32:17

Speaking about muscle and how we need to really exercise to maintain longevity, another thing we haven't talked about is nutrition. So, nutritionally, what does the body need to build and maintain muscle as we age?

SPEAKER_01 32:32

Uh so nutrition, I mean, I think it's important that we frame it correctly. Um, because once training is in place, nutrition becomes the support system, not the driver. Um, muscle is built in response to stimulus, and that stimulus is resistance training. Protein, and we talk about nutrition, protein provides the raw materials, but without that signal, the body has no reason to build or to maintain muscle. And this is where I see a lot of confusion with patients. Um, people focus heavily on how much protein they're taking in, their supplements, you know, the protein in exact gram targets. But they they may not be focusing on training. I mean, training with intensity progresses over time, uh, and it should be consistent. So, you know, they're trying to solve a stimulus problem with nutrition, and that just doesn't work. Now, with that said, protein is still essential. I mean, muscle is made up of amino acids, which are the building blocks of protein. So the body needs enough total protein and regular intake throughout the day. Um, you don't really store protein, so you have to actually ingest or digest or intake um daily. It becomes more important as we age because of something called anabolic resistance, which we mentioned earlier, which means that the muscle becomes less responsive to protein and to training. So older adults often need more protein and a stronger and a stronger stimulus to get the same results. So clinically, as far as protein intake, um, I think, you know, there's a lot of variances, but really a safe, um, unsafe numbers to actually consider would be about 1.2 to 1.6 grams per kilogram of weight per day. And, you know, and it also depends on um how actively you're training or your focus on muscle preservation. So typically if you're training higher or you may be a little older, you may need a little more, about that 0.7 to 0.8 grams per pound. And typically we we start recommending that for individuals who are doing a lot of resistance training or who um or over the age of 40, because that's typically where anabolic resistance starts to really show its head. Uh, but just as important as total intake, it's about distribution. Um, if someone eats most of their protein in one meal, they're missing opportunities to stimulate muscle throughout the day. So spreading protein across meals helps repeatedly activate it muscle protein synthesis. And part of that comes down to something called leucine threshold. Uh, leucine is an essential amino acid and it acts as a trigger for muscle building. So each meal needs enough protein to reach that threshold and to activate the process. Now, from a plant-based perspective, which I am, um, this is where the structure matters a little bit more. Um, plant proteins can absolutely support muscle, but they tend to have a slightly lower level of leucine and can be a little less dense per serving. So the strategy becomes slightly higher total intake, and then just making sure that you have a variety of protein sources. Um, and then once again, you to stimulate muscle growth, you have to have um that that constant um stimulus or training. Uh, and and clinically, we see that that works very well. Now, beyond protein, there are a couple of other things that are often overlooked. Uh, one is total energy intake. If someone is training hard or um but they're under-eating, then the body shifts into a more catabolic state and muscle maintenance becomes extremely difficult. The other one is recovery. Um, muscle isn't built during the workout, it's built after the workout, during recovery. Uh, so you know, you want to make sure you have things like your sleep in check and your stress is managed and um your overall nutrition. Um, all of these things play a major role in whether the body actually adapts. So if I simply place it, muscle is built through three things uh stimulus, nutrition, and recovery. And that order matters. Training is the signal, nutrition supports it, and recovery allows it to happen. And when those are aligned, that's when you see real change and lasting change.

SPEAKER_00 37:04

That's interesting that muscle is really built through recovery. I know recovery played a big role, but I never thought about it in that sense. And I'm sure you see a lot of mistakes that people make. But what are some of the most common mistakes you see people make when trying to build or maintain muscle for long-term health?

SPEAKER_01 37:20

The stimulus has to be enough and in very simplistic terms, you're actually tearing down the muscle fiber. And they're and so that muscle fiber actually needs to heal. And when it heals, it it actually becomes stronger. And so that's where the recovery is really important. Uh, you know, you you see people um who are constantly causing that stimulus, but after a while, if they're not allowing the recovery to happen, then they're actually doing more harm. They're going back, they're going into that catabolic state. Things usually kind of break down, um, not because people don't care, um, but because there is this mismatch between what they're doing and what the body actually and how the body needs to adapt. Um, most people feel like they're doing the right things. They're they're going to the gym and they're staying active and they're trying to eat better. Um, but when you look at outcomes, um, they're not building or maintaining muscle the way that they think that they are. And I say that very lovingly. Um one of the biggest issues is training intensity, like I just mentioned. Um, muscle only adapts when the challenge is at a cellular level. So when you perform that resistance training, you create that mechanical stressor or that tension in the muscle fiber. That tension causes that micro damage to the fibers, particularly the contract, uh, the um contractile units called myofibrils. Um, and that's the stimulus. But the important part is what happens next, like I like I just mentioned, is the um is the recovery. The the body repairs those fibers and reinforces them and makes them stronger and more resilient and often larger over time. So this process is called muscle protein synthesis. And here's the key that um that process only gets activated when the stimulus is strong enough. So if someone is lifting lightweights or stopping far from fatigue or just kind of going through the motions, um, they're not creating enough tension to trigger the response. And without that signal, there's no reason for the body to try to adapt. Um, so the fixes train close enough to fatigue that the muscle is actually challenged. Uh, and I know that that's hard because as human beings, we're designed to avoid discomfort. Um, but you need that discomfort to actually see progress. And then, you know, once that stimulus occurs, then like I said, the recovery is it becomes critical because the muscle is not built during the workout, it's built during the rest and repair. So um, after training, the body increases protein synthesis, but that process can take 24 to 72 hours depending on training intensity, age, um, recovery status. Uh, if recovery is inadequate due to poor sleep, um, being constantly under stress uh or having insufficient uh calories, then the body stays in, as I mentioned before, in that more catabolic state, meaning that it's breaking down or the breakdown is exceeding the repair. So instead of building muscle, you're slowly losing it. Now, another major issue I see is people relying too heavily on cardio alone. Um, you know, as we mentioned in the last segment, cardio is really important. It improves our cardiovascular health, it improves our mitochondrial function, and it improves our VO2 max. But without resistance training, there's a real risk over time of losing lean muscle mass, reducing resting metabolic rate, and lowering overall metabolic capacity. In our clinic, we see time and time again, I mean, particularly individuals who are just doing cardio, we see this hormone disruption. We can see like uh a lowering of their testosterone levels because of the you're in this constant state of being in a catabolic or breakdown. So we, you know, you see most professional athletes or athletes that are really good at what they do, um, they engage in, like we mentioned before, all three phases of of physical activity, the resistance training, zone two and the zone four and zone five. Going back to, you know, that catabolic state, particularly individuals who are um losing weight and not performing resistance training, um, we find that a significant portion of weight loss, sometimes 20 to 30 percent, and sometimes even more. I've actually seen one case where it was it was about 50 to 60 percent. Um, we see that weight loss actually comes from lean muscle mass. And the problem with that is that when that slows your metabolic rate, because once again, uh muscle is the regulator of your basal metabolic rate. Um, and when people put weight back on, or you see people who are yo-yoing, they actually put on more fat than they do muscle when that weight gain occurs. Um, and then of course, you know, all of this has long-term consequences because, you know, as I stated, you know, muscle regulates your glucose and maintains your metabolic rate and it and it provides physiologic reserve. So the solution is that cardio should support health, but resistance training must anchor it. Uh, another issue is a lack of progression. Um, the body adapts quickly. So if the stimulus doesn't increase, the adaptation stops. And that's why progressive overload is essential. So over time, this has to be an increase in resistance or increase in effort or an increase in training volume. So even small increases keep the signal active. Um, and then there's this inconsistency. So muscle response to repeated stimulus, not occasional effort. Um, studies show that as well as two to three resistance training sessions per week can significantly improve strength, muscle mass, and metabolic health, but it has to be consistent. Another common issue is overfocusing on nutrition while under training. You know, like I said, it's you you can't go uh any place without hearing about making sure that you're getting enough protein and then, you know, um, you know, people are taking an abundance of supplements. Um, but again, um, protein supports the process. It doesn't replace the stimulus. Um, and finally, there's often a fear of intensity, especially with aging. Um, people avoid heavier loads or higher effort. Um, but physiologically, that's exactly what preserves. Muscle fibers, bone density, and neurovascular, or I'm sorry, neuromuscular function. So without that stimulus, the body downregulates those systems. So if we had to kind of simplify all of this, um, to actually improve muscle and long-term health, um, you need to create enough tension to stimulate muscle fibers, allow recovery so those fibers can repair and grow. And also it's important to um progress over time to maintain adaptation. And you want to make sure that you're combining resistance training with cardio appropriately and you stay consistent week to week. Uh, you know, muscle is constantly adapting, either building or breaking down. Training provides the signal, recovery allows the repair, and consistency determines the outcome. And when those are aligned, that's when the body actually changes.

SPEAKER_00 44:51

For someone who is listening who wants to improve muscle mass and strength for longevity, what does a realistic weekly training framework look like? Now that you said how important consistency is, what's a good weekly training framework?

SPEAKER_01 45:04

Okay. I guess this is where we can kind of take bind everything together and make it make it practical. Um, so people don't need a perfect plan. Um, they need something that is clear, sustainable, and actually works long term for them. Um, so I like to think in terms of a simple weekly framework. Uh, at the foundation, you have resistance training. Um, and ideally that's about three to four times per week. Uh, and the goal here is not just movement, it's once again triggering that stimulus. Um, you and you want to make sure that you're training the major muscle groups and that you're using enough resistance and then you're getting close to fatigue. Um, because once again, that's what creates um improvement, that mechanical tension, that micro damage to the muscle fibers, and and this ultimately drives adaptation. So, from a physiological standpoint, each session stimulates muscle protein synthesis, which can remain elevated for roughly 24 to 48 hours, hours. So, spacing those sessions across the week allows you to repeatedly activate that process. Now, the second piece is the zone two cardio. And this is where a lot of people get confused because not all cardio is the same. Uh, zone two, as we mentioned earlier, is a lower intensity, steady work type of exercise. Uh, physiologically, this is where your body is primarily um burning fat. A lot of people refer to zone two as a fat-burning um zone. Your lactic acid level stay relatively low during this phase, and you can sustain the effort for long periods of time. Uh, a simple way to think about it is that you can hold a conversation, um, but you know you're working. I like to think of you can actually speak, but you can't sing. Um, and so this type of training is incredibly important because this is where you increase your mitochondrial density, you improve that fat oxidation or fat burning, and you build your aerobic base. This phase or zone two training, um, over time, it can make your body more efficient at producing energy and not relying on constant glucose intake. Now, I've, as I mentioned before, uh, you know, let's simplify how you actually calculate your zone two. And this is really um, like we said, 60 to 70 percent of your max heart rate. Easiest way is that two you subtract your age minus 220, um, and then you calculate that would be your max heart rate, and then you calculate the 60 or 70 percent, or for some people, you just can get your your zone two um 60 to 70 percent max heart rate by subtracting your age from 180. Now, a caveat is that you know, this is a very generic equation, and so it doesn't work for everyone. Um, you know, some people have a higher um zone two level, um, you know, some people have a lower based on uh levels of activity and fitness. So if you know, if there's a way that you can actually calculate your true max heart rate, um, then that would be the most accurate way to actually gauge in your zone two and your your zone four and your zone five training. Um and a lot of devices have that ability now, or you can do metabolic testing um to determine your zones. And then kind of moving to the third piece would be the the zone four, zone five, which is that higher intensity, that you know, 75, 90, or 80 to 90 uh percent max heart rate. Um typically during this phase, breathing is much heavier, um, conversation is difficult or not possible, not even possible. Um so this type of training uh produces more lactic acid, it pushes the cardiovascular system, and it stresses the body in a different way. And this, as we mentioned before, this drives VO2 max. It increases your cardiac output, it increases your oxygen delivery and your peak energy production capacity. So the difference simply zone two builds efficiency and endurance, zone four and five bills capacity and peak performance. And you need both. But from a weekly standpoint, this usually looks like zone two. Um, you do two to three sessions per week, normally 30 to 60 minutes. Um, the high intensity are zone four and five, one to two shorter sessions per week. Um, and then um outside of the structured training, um, daily movement still matters. Things like walking and staying active throughout the day. Um, because you want to maintain your metabolism recovery and overall energy balance, which happens with daily uh or constant movement. Uh, another important piece is recovery. Um, and I think a lot of people are recognizing how important recovery is now. Um, because the goal is not to train hard every day, it's to train effectively and recover well. Um, and that means making sure you're getting an um adequate sleep, you're eating enough to support your training, and you're allowing time between sessions to for recovery. Uh, because once again, that's where the muscle repair uh happens, the mitochondrial adaptation occurs and the system actually improves. And finally, everything needs to progress over time. This could be lifting slightly heavier, improving endurance, or increasing intensity. So even small improvements compound significantly, significantly over months and years. Um, so if someone's listening and thinking, what does this actually look like? A simple version would be three days of strength training, two to three days of zone two training, one day of higher intensity work plus daily movements. Uh, and that's it. You don't need extremes, you don't need, you know, but you do need to train your strength, your efficiency, and your capacity because that determines how your body performs and how it ages.

SPEAKER_00 50:59

Absolutely. It does sound like a sustainable weekly routine, like something that someone can really follow. And thanks for breaking that down in in layman's terms, if you will. It sounds like something obtainable for sure. And I think today we really explore something that's incredibly important. And muscle is not just about fitness, it's one of the most powerful predictors of long-term health and survival. So, for those listeners, if you're enjoying the Young Lab, learning how the body actually works, make sure that you subscribe and stay with us. Make sure you send this episode to someone it resonates with, which should be everyone. We're all aging. So make sure that you like and subscribe and share. And it's a pleasure just to talk to you. As always, Dr. Young, and I will see you next time.

SPEAKER_01 51:44

Yeah, no, it's always my pleasure. No, and I look forward to the next episode.

SPEAKER_00 51:48

Absolutely. Talk to you soon.