The more I study the importance of resistance training and the more I study the importance of doing weights, especially as you age, the more I've... the more I started kicking myself for being lazy about that. So now I try to do good two strength workouts out of every week at least and take it more seriously because especially as you age.
loss of muscle mass can be really debilitating. The technical term for that is sarcopenia. Sarco is the Greek word for muscle, and penia is loss, or muscle loss. So as people get older, they tend to lose muscle. And when you do that... you become frail and you lose...
functional capacity and then that starts off a vicious cycle right once that happens then you'll be less likely to be physically active and then of course when you're less physically active your muscles begin to waste away more and it's very debilitating so i think as we get older
and I'm getting older, it's more and more important to kind of incorporate that. So I think that's the one thing that I've taken to heart. From what you said there, it sounds like not doing resistance training, not doing... not lifting weights as you age, almost accelerates aging in any sort of superficial sense, but also in a physiological sense. You're increasing the speed of aging.
Yeah, I'm not sure if I'd think about it that way, but I think I'd kind of reverse it slightly, which is that, you know, aging is just... the clock ticking on, right? There's nothing we can do about age. But senescence is the way our bodies degrade as we get older. And what physical activity does, it's actually maybe the most important thing about physical activity.
is that it slows senescence, especially for certain organs and systems. And there are different kinds of physical activities. So there's endurance physical activities, you know, like running, walking, etc., swimming, and then strength or resistance physical activities. And they have different kinds of ways in which they slow. various properties of senescence, which we...
colloquially call aging. And all of them are important. And I think one of the things that's really interesting about humans, in fact, I think it may be the most important thing about this book, and you asked about myths earlier, the most important myth, I think.
by far, is this idea that as you get older, it's normal to be less active. And that is just not true. We evolved to be grandparents. We evolved to live. One of the things that's most interesting about humans, maybe, is that we evolved to live.
about 20 years or so after we stopped reproducing. No other animal does that except orcas, maybe killer whales. But with the exception of killer whales, humans have this really weird life history. We evolved to be grandparents. But grandparents in the old days weren't, you know...
retiring to Florida or I don't know what they do in England or whatever, go to Mallorca or whatever and, you know, kick up their heels and play golf or whatever with carts. Grandparents in the olden days, right, or in many cultures still today, are working, right? They're working in the fields.
they're gathering, they're getting food for their children and their grandchildren, they're helping with childcare. And that physical activity is, you know, that's what their job is, to be physically active. But in turn... That physical activity turns on an amazing suite of physiological processes that counter aging. It turns on repair and maintenance processes that not only keep our muscles strong, but also... Keep our DNA from accruing mutations. Keep our...
mitochondria numbers high, keep the cells in our brain from accumulating gunk so that prevents Alzheimer's and other forms of dementia. I mean, for every system of the body, physical activity. has benefits that slow the aging process. And so when you stop doing it, and that's the way in which you perceive it as accelerating aging. But really, it's the absence of physical activity which lets aging run amok.
In your first book in 2013, The Story of the Human Body, in chapter 12, you said, you used this phrase, use it or lose it, basically.
We evolve to use or lose our bodies. And I was sat with someone recently, and I was trying to figure out why it appears that when people retire, or the other instance I've seen is when their elderly partner passes away, it appears as if... they don't live much longer yeah it's kind of like kind of folklore or something that once you retire your days are kind of numbered yeah yeah
And I was trying to figure out the evolutionary reason for that, but it sounds like that's kind of what you've explained there. Well, I mean, I think part of that is depression, right? When you lose a partner, I mean, grief and depression. your cortisol levels go up, your immune system goes down. I mean, you know, it's really tough on your body. I mean, psychosocial stress plays a serious physiological toll. But also, as you just pointed out,
When people retire, they become less active. And that loss of activity... has enormous effects on every aspect of our body and our minds. Physical activity is important not just for physical health, but also vital for mental health. And I think a lot of the problems that... A lot of mental health issues we have today, depression, anxiety, some of them to some extent.
we can attribute that to less physical activity. And as people age, becoming less physically active, again, makes them much more vulnerable to a wide suite of diseases. So would you say we shouldn't retire? Or if you do retire, I mean, retiring is, again, another modern weird thing, right? Nobody retired in the past. I mean, if you're a farmer, it's like a subsistence farmer and name it any place, right? It's not like suddenly you hit 65 and all of a sudden...
You no longer have to work in the fields. You work in the fields until you're, you know, until you're dead, right? And hunter-gatherers don't retire. They continue to be physically active until they die, right? Or until they get too sick. So it's a very modern Western concept. And yes, we do.
you pay a price for it. But you, of course, can replace work that you do with challenging, rewarding, fun things to do. The important thing is just not to stop being physically active. One of my favorite studies. published, without a doubt, is a study done by a guy named Ralph Paffenbarger. He realized that places like Harvard are fantastic for studying aging because Harvard, like other... private universities never lets go of their alumni. So until the day you die, they're asking you for money.
on a regular basis. And so he got the Alumni Association, the Harvard Development Office, to let him follow a series of Harvard alumni from several years and can keep asking them. questions about their physical activity levels and also their diet and whether they smoked and stuff like that. And then you track them for 25, 30 years. And what he found was that the alumni, we have to correct it for every factor you could think of.
that as the alumni got older, the effect of physical activity on their health outcomes was bigger and bigger. So alumni who were in their 20s, 30s, and 40s, for example, who were exercising four or five times a week, they had about 20% lower death rate. By the time they got to their 60s and 70s, the alumni who were exercising more had 50% lower death rates. So as you get older, and this has been replicated again many times, but what he showed was that as you get older,
Exercise becomes more, not less important for maintaining your health. I've been thinking a lot about this because I was saying to Jack, my dad is 60-ish, but he's very, very out of shape. Very, very out of shape. And I was in Indonesia, and I was with my girlfriend, and we were going whitewater rafting. So we had to go down this really big hill. With all these stairs, it was like 300 metres of stairs. And I remember just thinking, my dad wouldn't be able to do this.
at his age at 60 and I want to be able to go down those stairs when I'm his age because at the bottom there was a fun activity with someone I loved and to think that I'll get to a point in my life where not so far away the grand scheme of things, where I won't be able to go up or down some stairs because I'm 60, because of my sort of genetic predisposition, as I saw it, was quite sad. But having heard you say that, it really feels much more like a choice than it is genetics.
Yeah, look, we have this expression in my field, which is that genes load the gun and environment pulls the trigger, right? Some of us have genetic predispositions towards being more likely to get diabetes or heart disease or this or that or the other. Our great-great-great-grandparents in different environments weren't getting these diseases, or they were getting them at much, much, much lower frequencies. It's not because they were dying earlier. It's because these diseases were less common.
I think we too often blame our genes for many of these diseases, many of these health problems. And I'm not in any way denying the role of genetics, but that environment is way more important. And we have control over our environment to some extent. And so if you want to reduce your risk of cardiovascular disease, reduce your risk of diabetes, reduce your risk of Alzheimer's disease.
dementia, exercise isn't a magic bullet. It's not going to prevent you from getting those diseases completely, but it lowers your risk quite substantially. And we know why, too. I mean, we have an immense amount of data. on why that's the case. For every single one of these diseases, we understand the mechanisms by which physical activity
has important mechanistic effects on these diseases. So there's epidemiological data, there's mechanistic data, there's personal data. The problem is that it's hard to do, right? It takes willpower. to overcome the inertia of doing what's completely normal, which is wanting to take it easy. I just flew yesterday from Denver to Boston.
And in the airport, there are these escalators right next to the stairway. And the escalator and the stair, it wasn't a huge stairway. Everybody's lining up to take the escalator. And the stairs are totally free. being me. Of course, I'm not allowed to take the escalator unless I have to, right? So I ran up the stairs, but those people taking the escalator, there's nothing wrong with them. They're not lazy. It's just an instinct, right? It's an instinct.
to take it easy when you can, right? And we now live in a world where everybody can do that, right? Because we have escalators and lifts and cars and shopping carts and all these wonderful devices. to make our lives easier. And now you have to overcome this fundamental basic instinct to take it easy in order to be physically active. And that's basically what exercise is. And furthermore, if you're unfit and you're not really... Exercising isn't any fun, right? It's unpleasant.
you know you sweat you get hot and you get cranky and you know um and and it's not that rewarding uh until you get fit and so uh people hate it right um and uh and then we blame them for being lazy but they're actually just being They're just being normal. And I think we need to have more compassion towards people who struggle to exercise. Quick one before we get back to this episode. Just give me 30 seconds of your time.
Two things I wanted to say. The first thing is a huge thank you for listening and tuning into the show week after week. It means the world to all of us and this really is a dream that we absolutely never had and couldn't have imagined getting to this place.
But secondly, it's a dream where we feel like we're only just getting started. And if you enjoy what we do here, please join the 24% of people who watch this channel regularly and have hit that subscribe button. It means more than I can say. And if you hit that subscribe button...
here's a promise I'm going to make to you. I'm going to do everything in my power to make this show as good as I can now and into the future. We're going to deliver the guests that you want me to speak to and we're going to continue to keep doing all of the things you love about this show. Thank you. Thank you so much. Back to the episode. This basic instinct to take it easy. Are we evolved to be lazy, take escalator riders? Well, I wouldn't use the word lazy, but we are evolved.
to take it easy, to rest whenever possible. So we've now got ourselves into a bit of a comfort crisis here because everything in our lives is optimizing us for convenience and ease. Right. Right. And well, it's also it's it sells, right? I mean, comfort. I mean, I mean, who prefers to sit in economy as opposed to business class?
Nobody, right? Comfort is nice, right? Who prefers shoes that are uncomfortable, right? We, you know, comfort's, you know, we love comfort, right? But since when is comfort necessarily better for you? I mean, are comfortable shoes actually better for you than going barefoot? Are comfortable chairs better for you than taking the stairs? It is in the short term, or at least it appears to be today. Right. Yes, because we often value the short-term benefit over the long-term cost, right?
Hyperbolic discounting is the technical term for that. So we live in a world where we pay extra for comfort and we'll prefer it. But now we also live in a world where... We have to now go out of our way to be physically active because it's no longer necessary. And so again, I go back to my original statement, which is that people have evolved to be physically active for two reasons and two reasons only, when it's necessary or rewarding.
When we don't make it necessary, we need to figure out ways to make it rewarding. And that's hard. It's very hard.