How to combat muscle loss and anabolic resistance with Dr. Richie Kirwan! 🏋️‍♂️💡 Discover the importance of maintaining muscle mass and strength as we age, and gain practical strategies for improving muscle health through exercise and nutrition. 📊
In part two of this engaging episode of the Physical Activity Researcher Podcast, host Dr. Olli Tikkanen continues the conversation with Dr. Richie Kirwan, a lecturer in nutrition and exercise physiology at Liverpool John Moores University.
Dr. Kirwan delves deeper into the complexities of muscle mass loss and anabolic resistance, highlighting how inactivity, hormonal changes, and other factors contribute to age-related declines in muscle mass and strength.
Dr. Kirwan explains the multifactorial nature of anabolic resistance, discussing how the body’s response to anabolic stimuli such as exercise and protein changes with age. He elaborates on the critical role of maintaining physical activity throughout life to mitigate these effects and preserve muscle function.
The discussion also covers the impact of hormonal changes, particularly in older adults, and the benefits of resistance training and adequate protein intake in combating muscle loss and enhancing strength.
This episode offers valuable insights for researchers, clinicians, and anyone interested in understanding the interplay between muscle health, aging, and chronic disease prevention. Tune in to learn practical strategies for maintaining muscle mass and strength, ensuring better health outcomes as we age.
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Explore our Wearables, Â Experience sampling method (ESM), Sleep, Â Heart rate variability (HRV), Sedentary Behavior and Physical Activity article collections for insights on related articles.
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Refer to our article "Physical Activity and Sedentary Behavior Measurements" for an exploration of active and sedentary lifestyle assessment methods.
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This is the Physical Activity Researcher Podcast, a podcast for researchers of sedentary behavior, physical activity, and sports. Join for a relaxed dialogue about research design, practicalities, and well, anything related to research. Learn from your fellow researchers useful and relevant information that does not fit into formal content and limited space of scientific publications. And here is your host, researcher and entrepreneur Ollie Tickenham. Yeah, and how is it? I think I haven't looked into this in 10 years after my PhD. So do we do we know more from last 10 years? Why do we lose muscle mass and strength? Because I'm thinking like, I think this that we lose more muscle mass in in a distant muscles. So for example, coughs, we lose more muscle mass than than in thighs because the nerve is longer. So if I remember right, I think this bigger chance of a motor neuron dying when it's longer, which kind of doesn't support the inactivity thing that you are not just using because there seems to be also a kind of connection between the nerve length. Do we know? I might remember wrong. So feel free to correct me if I'm talking nonsense. So like I was saying, what we know at the moment is that it is very, very much a multifactorial disease. But the prime, let's say, initial reason for people losing that muscle is inactivity. And it might sound like an oversimplification. But what we see is that as people become older, and I think it's quite like if you think about it, it does make quite a bit of sense. After university, a lot of people start becoming less active, they get into jobs, they spend a lot more time sitting down. As a society, we have a lot less physically active jobs. And then if you get into, let's say the retirement age area around 60, people stop working altogether. And unless they're quite dedicated, their activity levels drop considerably. And it's around that age when we see massive drops in muscle mass and strength. So inactivity is the main driver, but there's a number of other factors involved as well. And one of those primary factors is something that we call anabolic resistance. And it's a bit of an umbrella term that is used in relation to the body's inability to react sufficiently to what we would call anabolic stimuli. And our two primary anabolic stimuli are exercise, particularly resistance exercise, but exercise and protein. So what it means is that we can give the body the same dose, for want of a better word, of exercise or protein, but it won't react as strongly to it and build muscle as efficiently as a would as a young person. So to give an example, I think the best example of anabolic resistance comes with protein feedings. And if we look at a lot of the research, if you give a young person, when I say a young person, somebody around their twenties, if you give them the dose of a high quality protein, like whey protein, if you give them 20 grams of that whey protein, you can almost maximally stimulate muscle protein synthesis, which is the process that we use for building muscle and for muscle repair. If you give an older person that 20 gram dose of whey protein, you do not see as much a response to that. And we've actually seen that you might need to give them twice that amount. So maybe 40 grams or even more protein just to get the same amount of a response as a younger person. So you got 20 grams over here, but you got 40 grams for this older person. And that's a, that's a lot of protein. And if you look at, let's say cross sectional data on diet in, in the UK, at least, you see that older people are very, very rarely getting that much protein in a single meal. I mean, in fact, protein is, is quite low in the, the macronutrient intake in, in, in older adults, especially. But then there's other factors that feed into that there's, we see an increase in inflammation in older people. Part of that comes from, you know, having higher levels of body fat. We see decreases in the ability to actually digest food and to digest protein, which can have an effect on them as well. And then we also see just the effects of being, we see a cyclical effect, which I like to call the sarcopenic obese cycle is whereby older people become inactive. They lose muscle mass. That makes it harder for them to move. They tend to gain a little bit of body fat because they're not moving as much. That little bit of body fat makes them a little bit heavier, which makes movement even harder, which reduces movement, and then reduces muscle. And we have this horrible cycle going around and it's very, very hard for them to break out of that. So yeah, there's a number of factors involved. And you said about the anabolic resistance, has it been linked to the hormonal media of the person? Or what's what's driving it? It can absolutely be related to that as well. So we know that in older men, for example, we see a small decline in testosterone over the course of their life. So basically from the actually in some men from the their late 20s onwards, we see that decline in testosterone. In women, we see around the age of menopause massive drops in progess, sorry, in estrogen. And we know that estrogen in women carries out many of the same functions as testosterone on men. So it has quite an anabolic function. We see that decline, but it's kind of harder in women to be sure if that's playing a major role, because we also know that around time of menopause, usually for a lot of women tends to be a period of decline in physical activity as well. So we do have this drop in an anabolic hormone in women, but it's very, very hard to say how much of the the effect of sarcopenia is generated just from that one cause. And is the drop the same basically for active and inactive people? So do we do we see a difference in the anabolic resistance between people who are active and who are not? Yeah, so in people who remain active throughout their life, we do not see a considerable drop or a considerable increase in anabolic resistance. People who seem to maintain activity throughout their life seem to be able to respond to exercise and to dietary protein quite effectively, at least much better than individuals who become sedentary. And unfortunately, in today's population, we have a large proportion of the population that is sedentary. Yeah. And what what do you think is the is the mechanism? Why do the active people are able to avoid the anabolic resistance? Is it the is it the hormone related or do we know anything? Why? Why is it again? It's something that we're not 100% sure of. So the whole driving the, let's say the drivers of anabolic resistance, we do know that the mTOR pathway, just for anyone who might not be familiar, we know mTOR pathway is a metabolic pathway associated with muscle protein synthesis within muscle. Some research has come out indicating that if that mTOR pathway becomes less sensitive as we get older, and we believe that in some individuals that are less active, the signaling pathway in mTOR is becomes less sensitive through inactivity. But because the mTOR pathway and all of the associated pathways with with muscle protein synthesis are so complicated, it's very, very hard point or pinpoint where the, you know, the the original cause of this is. 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Don't compromise on the quality of your research or the project timeframes. Discover the convenience and power behind our solution at sense dot Fibian dot com. That is S E N S dot Fibian dot com. Fibian created by researchers for researchers. Yeah, that's that's interesting. Do you have anything else to add into this, this kind of part of the topic we are discussing? Well, I suppose like just from that, like, I always like to kind of say to people that kind of focus on how important muscle is. And while we are talking about like, you know, being strong, and we have originally been talking about cardiovascular disease, muscle mass and muscle strength are associated with so many beneficial outcomes. We know that people with lower levels of muscle mass tend to have, like I said, a higher risk of falls and fractures, they've got a higher risk of osteoporosis. They tend to have a higher risk of a number of other conditions such as we see higher risk of chronic kidney disease, a higher risk of a non alcoholic fatty liver disease, higher risk of cancers. And then we also see in people who have lower muscle mass, a lower quality of life from another, a number of points. But that can also be related to poor cognitive health, which we see in lower muscle mass. So people don't, their brains don't work as efficiently as efficiently when their muscle mass is not as well maintained. And we also see higher levels of depression. And that seems like a bit funny. But if you think about it, if somebody is has become very, very inactive and they find it very, very difficult to get out of their home and to go outside and see their friends, that's going to have a major impact on how they feel about themselves. If they lose independence, and they're not able to socialize as much as possible, you know, you can understand how that might have an effect on somebody's depression risk as well. So yet, like, I would say, muscle masses is it's a key factor that we need to maintain as we as we age. And it should be something that we should be aiming to work on from as young an age as possible. Because what I like to think of is if you think of muscle mass as a buffer against age-related decline, the higher that you can build that buffer as you, you know, from from a young age, the slower, well, your decline will be the same speed, but you will, you will, it'll take you a longer time to get to a point where that's going to have a major negative impact on your health. So build muscle when you're young and try and maintain it as much as you get older. Yeah, yeah, that makes sense. And I think it's just very interesting when you said that that people when they stop studying, they they start being less less active. But then when they retire, they don't need to need to do that. Is there any study showing because the loss of strength is quite steep in the later part of life, I think, after 70 or something. Is there any study showing that it would be related to retirement and then being less active, using muscles less or or do we know anything anything on that? This is just speculation. So unfortunately, there's nothing that can like directly related to retirement. But I think if we look at the time course of those changes in muscle mass and what you've said there is spot on, we see that muscle mass declines gradually. But from our, let's say our late 30s onwards, it declines gradually. But once we hit the 50s and 60s, that decline becomes much more significant. And actually, the decline in strength becomes even more significant over time. And it is around that, let's say, late 50s, early 60s period, when traditionally, a lot of people would be retiring, and we can only associate and speculate at the moment that it's due to the fact that people just become a lot less active. Who? Yeah, of course, this you could compare some people who still keep doing strength training, and you could see probably the difference here would be interesting study. And that is a good point, because we do have a few studies that look at what we call lifelong active individuals. So people who, for example, maintain some form of a sport, usually master's athletes. And we do see that in endurance master's athletes, and in strength sports master's athletes, so people who do weightlifting, for example, we see that obviously the weightlifters maintain the most muscle mass, but endurance athletes also maintain a fantastic level of muscle mass as well. The weightlifters maintain more strength. But if you compare them to the general sedentary population, there is a major difference between muscle mass and muscle function as well. So those individuals who aren't exercising just do not have anything near the levels of muscle and strength that the lifelong athlete tough. Yeah, and what would be then the strategy is based on all this, how to increase muscle mass, how to increase strength? Is it even important to increase muscle mass, or is it enough to increase strength from training, nutrition perspective? So, luckily, muscle remains a relatively plastic tissue, even into advanced age. And we have a number of studies that show that resistance exercise programs, so particularly progressive resistance exercise. And by that, I just meet lifting weights, or in some cases, it can be easier versions, like using resistance bands to do exercise, do result in increases in both muscle and strength in all rather. What we see is that strength seems to improve much more quickly than muscle mass itself. And that's probably due to improvements in neural control of muscle motor units initially. But strength, beside those increases in muscle size, do come as well. So these programs tend to focus on, let's say, full-body routines where people are focusing on progressive overload. So basically, people need to be pushing themselves. It's not just kind of a matter of just going and lifting a few weights, although doing anything is better than nothing. But having a guided program where people can be trained into how to progress their lifting and their strength over time, so using different weights, machines, and adding more weight, so they're challenging their muscles constantly over time. And so we see that those resistance exercise programs work. We also see that when you add in some form of protein supplementation into individuals who have lower protein diets, so adding protein on top of the resistance exercise seems to potentiate that effect, and you get an even greater increase in muscle mass over time as well. Yeah, so pretty classic. You push harder, and you eat better. That's it work. Thanks for joining us this week on physical activity research through podcast. If you like the show, make sure you never miss an episode by subscribing or following the show on Twitter. This podcast is made possible by listeners like you. Thank you for your support. If you found value in the show, we would really appreciate rating on Apple podcast or whichever app you use. Or if you would, in a real old-school way, simply tell a friend about the show. It would be a great help for us. We have a fantastic lineup of guests before coming episodes, so be sure to tune in. Thank you all for your support, and have a great day.
