In this edition of Wisdom Wednesdays, the focus is on the incredible malleability of the human heart, inspired by my personal experience with open-heart surgery. The episode delves into historic and revolutionary studies, starting with the 1966 Dallas Bedrest Study, which showcased the drastic effects of inactivity on cardiovascular health.
It then explores follow-up studies that demonstrated how structured exercise programs can not only reverse cardiac damage but also make the heart more efficient and youthful, even in middle-aged individuals.
I explore the importance of consistent, smart exercise, combining moderate aerobic activity and high-intensity intervals, to maintain a healthy heart into older age. The show concludes with a powerful reminder of the human body's need for physical activity, supported by an impactful quote from Professor Frank Booth.
00:00 Introduction and Personal Connection
00:41 The Dallas Bedrest Study: A Groundbreaking Experiment
01:41 The Impact of Bedrest and the Power of Retraining
03:54 Long-Term Effects and Follow-Up Studies
05:31 Modern Research: Reversing Cardiac Aging
06:23 Exercise Protocols for Heart Health
12:57 Key Takeaways and Final Thoughts
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Mark as Played
Transcript
Episode Transcript
Available transcripts are automatically generated. Complete accuracy is not guaranteed.
Speaker 1 (00:08):
Hey, everybody, welcome to another edition of Wisdom Wednesdays. Today
we are going to dive into something that is not
just fascinating, but it's also pretty personal for me because
we're going to talk about the heart, Your heart, my heart,
and how incredibly malleable are plastic it really is. And
if you're not a regular listener, and this is personal
(00:31):
for me because in January this year, I went through
open heart surgery to correct a dodgy aortic valve that
I was actually born with. So we're going to talk
about today through the lens of one of the most
groundbreaking studies ever in exercise science, and it's called the
Dallas bed Rest Study. And then there's been a series
(00:53):
of studies after that about the Dallas bed Rest and
Retraining Study and it's kind of got a fifty year
legacy and this researchs really changed medicine. And after my
own experience with heart surgery, I can tell you that
this isn't just theory, it's actually life saving knowledge. And
it starts. The story starts in nineteen sixty six, five
(01:15):
healthy young men in their early twenties, fit and no
health issues, volunteered for a radical experiment what they had
to do was lie flat on their backs for three weeks.
No walking, no standing, no sleeky lapse to the fridge,
just bed rest and probably a student's dream get paid
(01:36):
to lie in bed for three weeks, But what happened
was a bit of a wake up call. In just
twenty one days of complete inactivity, there are cardiovascular systems
aged by what would normally take thirty years of living.
Their VO two max, which is they measure the gold
(01:59):
standard measure of your cardio respiratory fitness or horsepower if
you like it, actually dropped by twenty seven percent in
three weeks, and their cardiac output, which is how much
your blood how much blood sorry, your heart pumps per
minute plummeted by twenty six percent, and the stroke volume,
(02:20):
the amount of blood that's pushed out per heartbeat, dropped
a whopping thirty one percent, and its submaxim sub maximal effort.
Just like light cycling or light jogging, Their heart rate
and blood pressure skyrocketed. Their hearts were working harder, just
doing less, And this was the original use it or
(02:45):
Lose it research study, But then came a bit of
a twist. These men spent the next eight weeks in
a structured endurance training program. And this wasn't a walk
through the park. It was rigorous aerobic and anaerobic training
and it was five to six hours per week and
the results were pretty bloody stunning. Their VO two macs
(03:08):
increased by forty five percent, so went way above what
they were before they came in. Their stroke volume jumped
forty eight percent, and their cardiac output and returned to
it and actually even surpassed their baseline levels. And the
cardiovascular damage from complete rest was not just reversible, it
(03:31):
was reversible and actually went higher through targeted, consistent effort.
And remember this wasn't just a theoretical benefit. This is
actually a seismic shift in how heart attacks were treated
from their on no more prolonged bed rest after heart attacks.
This was the genesis of cardiac rehabilitation. And if we
(03:55):
fast forward thirty years, the researchers tracked down the same
thive men, now all still in their fifties, and they
tested them again. This time there was no bad rest.
They just wanted to examine how three decades of normal
aging had impacted their hearts, and to the researcher surprise,
(04:15):
their VO two max had only declined by twelve percent
in thirty years, and compare that to the twenty seven
percent crash after three weeks of bad rest. Now, what
probably happened was that training study that they did. That
they went through. The bed rest and training study probably
locked in for these guys the importance of fitness, and
(04:38):
so they probably had lifelong exercise and that's why their
hearts when they were in their fifties actually seemed a
lot better than what was the original thirty years of aging. Right,
But this time they actually trained these guys again, but
this was a bit of a gentler program, and it
(04:59):
was long. It was two hundred and fifty minutes a week,
and it was progressive overload. Right. They didn't start them
as hard as they did when they were younger. They
built it up over time. But again they got significant
gains their VEO two max roles fourteen percent, right, not
quite as much as in their youth, but that's that's massive. Like,
(05:19):
if you're in your fifties and you can increase your
VO two max by fourteen percent, that has a really
profound effect on your risk of all cause mortality. Now,
let's bring this study forward now into the future. Twenty eighteen,
the same research team and this was at Dallas. They
(05:40):
asked a big question, can you reverse cardiac aging in
the middle age, not with a late level training, but
with a doable, realistic, although reasonably vigorous exercise plan. So
what they did is they recruited sixty one healthy but
sedentary middle aged adult typical population and their average age
(06:02):
was fifty three. Half of them and were assigned a
low intensity stretching and yoga control right, So these were
the control group. They didn't do nothing, they were doing
low intensity exercise and the other half got a smart
structured training program. And this was two years and the
(06:24):
key ingredients of this program and I will send a
link to this if you want to really get in
and geek out, but essentially it was four to five
days of training per week and it started off with
moderate intensity aerobic work what we call zone two. Now
you may have heard of zone two. That's in terms
of heart rate training zones, and it's sixty to seventy
(06:46):
percent of your maximum heart rate. This is the bread
and butter of endurance training. And if you don't have
a heart rate monitor, you don't know your maximum heartbrate.
The easiest explanation of zone too is you can talk,
but you can't sing, right, So you should be able
to hold a conversation, but somebody should know if they're
(07:08):
talking to you on the phone that you're actually exercising.
If you can sing, you're in zone one. If you
can't talk in full sentences, you're in zone three or higher. Now,
this modern intensity aerobic work is really important because it
is very very beneficial for our mitochondria and gives us
(07:28):
what we call an aerobic base. And then they added
in high intensity intervals and specifically they used my favorite
protocol and the one that I'm actually using for my
cardiac rehab, and it's their Norwegian style four x four protocol.
So what you do is you go four minutes hard
(07:49):
and at the end of those four minutes you should
be at ninety to ninety five percent of your max
heart rate or a perceived exertion of nine out of ten. Right,
So you do that for four minutes. Then you have
three minutes of active recovery down to about zone two
just to count, so you're keeping moving but at low
intensity that three minute recovery, and you do four intervals, right,
(08:13):
So it's four intervals with three recovery it's twenty five
minutes in total. And then they added into this one
long weekly session of endurance training and importantly as well,
they did twice weekly all body strength training. Right, so
this wasn't brutal, but it was a pretty reasonable, vigorous
(08:36):
exercise program, and it was calculated and it paid off.
After two years of this training, their VO two max
increased by eighteen percent. Now, this is a massive improvement
in middle age. And like I said earlier on this,
if you're in your fifties and you can increase your
VO two max by eighteen percent, there's not much else
(08:58):
out there that you could do that would juice your
risk of all cause mortality as much as increasing your
view two march by eighteen percent. But there was a
deeper win here. Their hearts actually got younger. So when
they really dug into looking at how their heart was performing,
their left ventricular stiffness. So you're left ventrical, that's that
(09:22):
you think about that the rooms of your heart, if
you like you're left ventricle, is this important room? This
is this is where the heart, the heart or the
chamber that fills up with blood and then it squeezes
and that's when your heart beats and actually pumps the
blood throughout your body. So your left fend. The stiffness
of your left ventricle, essentially how rigid or elastic it is,
(09:46):
is really important. And in these guys, their left ventricular
stiffness drops significantly. That meant that the heart could relax better,
it could fill more efficiently, and it could pump more
blood per beat. Now this is really important. So with me,
when I had that dodgy aortic valve, a bicuspit valve,
(10:07):
what that meant was every time that blood pumped out
of the left ventricle, and because my valve didn't shut correctly,
over time, some of the blood came back in and
that stretched the left ventricle. Now I was lucky that
I caught it relatively early. If I'd have waited another
year eighteen months, my left ventricle would have got much
(10:30):
stiffer and also would have stretched to the point of
no return. And that's what we call heart failure. When
you hear of heart failure, that's what it is. You're
left ventricle is actually stretching to the part of no return,
and it gets really stiff and it just does not
work well. Now, what also happened in these people is
their stroke volume also went up. The amount of blood
(10:53):
that they could pump out with every heartbeat, right, which
is really important. The heart size actually increase, So this
is a physiological adaptation. And a result of all of
that is that the resting heart rate went down because
the heart, because it was more efficient, didn't have to
(11:13):
beat as often. In real terms, this meant that they
were fitter, they have more efficient and more youthful hearts.
And in the control group, they didn't have any change,
any positive change. In fact, their heart function decline because
remember this is a two year study and they were
two years older and they had that two years of decline.
(11:35):
So let's break this down really simply in Layman's terms. So,
when your heart becomes stiff, that left ventricular stiffness, it
loses its ability to relax and fill with blood efficiently.
That is a direct pathway to heart failure with preserved
dejection fraction. That's what we talk about, and that's an
increasingly common and stubborn form of heart failure, especially and
(12:00):
older adults. And here's the kicker that twenty eighteen studies
showed that this trajectory is not inevitable. If you intervene
in middle age, you can stop this stiffness from setting
in the heart remains plastic or changeable into your fifties
and beyond. Now, the same research group did another study
(12:23):
where they took people in their sixties and they trained them,
and they didn't see the same results, right, So part
of that conclusion was you got to get on this
when you're in their fifties. But actually, when you look
into the detail, they did admit that the training intervention
that they did in the sixties wasn't as comprehensive as
the training intervention in the fifties. So there's still a
(12:45):
little bit of a question. But what we do though
is as your heart ages, it like all tissues in
the body, they lose their elasticity, right, So what does
this mean. It means that a couple of things. Number One,
your heart remembers. It remembers that three weeks of doing
nothing can wreck you more than three decades of aging.
(13:09):
So we have to be moving if we want to
have a healthy heart. But it also means that consistent
smart exercise, especially when it includes a mix of baseline
aerobic zone two and high intensity interval training that doesn't
just increase your fitness. This is about cardiac uth. It's
about making your heart younger, and if your heart gives up,
(13:33):
it's all over, right, And we're not talking about marathons here, right.
That twenty eighteen study met the public health guidelines right,
one hundred and fifty to three hundred minutes a week,
with some of it high intensity interval trainings and strength training.
I think that's also important in this study. It is achievable,
it is sustainable, but you've got to do the work.
(13:54):
That's the key thing. So the big take home here
is if you're in your forties and your fifties, or
you're guiding or know somebody is, this is the moment
to get on top of this because the longer you wait,
the harder it actually becomes. And if you're younger, don't
be complacent because your heart can age really really quickly
(14:16):
with lack of movement. In the end, your heart actually
wants and needs to be challenged. It was built to
respond and it responds to your environment. If you do
very little, your heart age is super super quick. But
if you actually do do the training, your heart will
respond and it will get and can get younger, and
(14:40):
you just have to give it the right kind of push.
And I'll leave you with probably my favorite quote of
any research journal I've ever read, from the Journal of
Applied Physiology in twenty twelve by Professor Frank Booth, legendary
exercise physiologist. He said, the human genome has not changed
(15:00):
in over forty five thousand years. Their current human genome
requires and expects us to be highly physically active for
normal functioning, and that is certainly the case for the heart.
Catch you next time.
Hey, everybody, welcome to another edition of Wisdom Wednesdays. Today
we are going to dive into something that is not
just fascinating, but it's also pretty personal for me because
we're going to talk about the heart, Your heart, my heart,
and how incredibly malleable are plastic it really is. And
if you're not a regular listener, and this is personal
(00:31):
for me because in January this year, I went through
open heart surgery to correct a dodgy aortic valve that
I was actually born with. So we're going to talk
about today through the lens of one of the most
groundbreaking studies ever in exercise science, and it's called the
Dallas bed Rest Study. And then there's been a series
(00:53):
of studies after that about the Dallas bed Rest and
Retraining Study and it's kind of got a fifty year
legacy and this researchs really changed medicine. And after my
own experience with heart surgery, I can tell you that
this isn't just theory, it's actually life saving knowledge. And
it starts. The story starts in nineteen sixty six, five
(01:15):
healthy young men in their early twenties, fit and no
health issues, volunteered for a radical experiment what they had
to do was lie flat on their backs for three weeks.
No walking, no standing, no sleeky lapse to the fridge,
just bed rest and probably a student's dream get paid
(01:36):
to lie in bed for three weeks, But what happened
was a bit of a wake up call. In just
twenty one days of complete inactivity, there are cardiovascular systems
aged by what would normally take thirty years of living.
Their VO two max, which is they measure the gold
(01:59):
standard measure of your cardio respiratory fitness or horsepower if
you like it, actually dropped by twenty seven percent in
three weeks, and their cardiac output, which is how much
your blood how much blood sorry, your heart pumps per
minute plummeted by twenty six percent, and the stroke volume,
(02:20):
the amount of blood that's pushed out per heartbeat, dropped
a whopping thirty one percent, and its submaxim sub maximal effort.
Just like light cycling or light jogging, Their heart rate
and blood pressure skyrocketed. Their hearts were working harder, just
doing less, And this was the original use it or
(02:45):
Lose it research study, But then came a bit of
a twist. These men spent the next eight weeks in
a structured endurance training program. And this wasn't a walk
through the park. It was rigorous aerobic and anaerobic training
and it was five to six hours per week and
the results were pretty bloody stunning. Their VO two macs
(03:08):
increased by forty five percent, so went way above what
they were before they came in. Their stroke volume jumped
forty eight percent, and their cardiac output and returned to
it and actually even surpassed their baseline levels. And the
cardiovascular damage from complete rest was not just reversible, it
(03:31):
was reversible and actually went higher through targeted, consistent effort.
And remember this wasn't just a theoretical benefit. This is
actually a seismic shift in how heart attacks were treated
from their on no more prolonged bed rest after heart attacks.
This was the genesis of cardiac rehabilitation. And if we
(03:55):
fast forward thirty years, the researchers tracked down the same
thive men, now all still in their fifties, and they
tested them again. This time there was no bad rest.
They just wanted to examine how three decades of normal
aging had impacted their hearts, and to the researcher surprise,
(04:15):
their VO two max had only declined by twelve percent
in thirty years, and compare that to the twenty seven
percent crash after three weeks of bad rest. Now, what
probably happened was that training study that they did. That
they went through. The bed rest and training study probably
locked in for these guys the importance of fitness, and
(04:38):
so they probably had lifelong exercise and that's why their
hearts when they were in their fifties actually seemed a
lot better than what was the original thirty years of aging. Right,
But this time they actually trained these guys again, but
this was a bit of a gentler program, and it
(04:59):
was long. It was two hundred and fifty minutes a week,
and it was progressive overload. Right. They didn't start them
as hard as they did when they were younger. They
built it up over time. But again they got significant
gains their VEO two max roles fourteen percent, right, not
quite as much as in their youth, but that's that's massive. Like,
(05:19):
if you're in your fifties and you can increase your
VO two max by fourteen percent, that has a really
profound effect on your risk of all cause mortality. Now,
let's bring this study forward now into the future. Twenty eighteen,
the same research team and this was at Dallas. They
(05:40):
asked a big question, can you reverse cardiac aging in
the middle age, not with a late level training, but
with a doable, realistic, although reasonably vigorous exercise plan. So
what they did is they recruited sixty one healthy but
sedentary middle aged adult typical population and their average age
(06:02):
was fifty three. Half of them and were assigned a
low intensity stretching and yoga control right, So these were
the control group. They didn't do nothing, they were doing
low intensity exercise and the other half got a smart
structured training program. And this was two years and the
(06:24):
key ingredients of this program and I will send a
link to this if you want to really get in
and geek out, but essentially it was four to five
days of training per week and it started off with
moderate intensity aerobic work what we call zone two. Now
you may have heard of zone two. That's in terms
of heart rate training zones, and it's sixty to seventy
(06:46):
percent of your maximum heart rate. This is the bread
and butter of endurance training. And if you don't have
a heart rate monitor, you don't know your maximum heartbrate.
The easiest explanation of zone too is you can talk,
but you can't sing, right, So you should be able
to hold a conversation, but somebody should know if they're
(07:08):
talking to you on the phone that you're actually exercising.
If you can sing, you're in zone one. If you
can't talk in full sentences, you're in zone three or higher. Now,
this modern intensity aerobic work is really important because it
is very very beneficial for our mitochondria and gives us
(07:28):
what we call an aerobic base. And then they added
in high intensity intervals and specifically they used my favorite
protocol and the one that I'm actually using for my
cardiac rehab, and it's their Norwegian style four x four protocol.
So what you do is you go four minutes hard
(07:49):
and at the end of those four minutes you should
be at ninety to ninety five percent of your max
heart rate or a perceived exertion of nine out of ten. Right,
So you do that for four minutes. Then you have
three minutes of active recovery down to about zone two
just to count, so you're keeping moving but at low
intensity that three minute recovery, and you do four intervals, right,
(08:13):
So it's four intervals with three recovery it's twenty five
minutes in total. And then they added into this one
long weekly session of endurance training and importantly as well,
they did twice weekly all body strength training. Right, so
this wasn't brutal, but it was a pretty reasonable, vigorous
(08:36):
exercise program, and it was calculated and it paid off.
After two years of this training, their VO two max
increased by eighteen percent. Now, this is a massive improvement
in middle age. And like I said earlier on this,
if you're in your fifties and you can increase your
VO two max by eighteen percent, there's not much else
(08:58):
out there that you could do that would juice your
risk of all cause mortality as much as increasing your
view two march by eighteen percent. But there was a
deeper win here. Their hearts actually got younger. So when
they really dug into looking at how their heart was performing,
their left ventricular stiffness. So you're left ventrical, that's that
(09:22):
you think about that the rooms of your heart, if
you like you're left ventricle, is this important room? This
is this is where the heart, the heart or the
chamber that fills up with blood and then it squeezes
and that's when your heart beats and actually pumps the
blood throughout your body. So your left fend. The stiffness
of your left ventricle, essentially how rigid or elastic it is,
(09:46):
is really important. And in these guys, their left ventricular
stiffness drops significantly. That meant that the heart could relax better,
it could fill more efficiently, and it could pump more
blood per beat. Now this is really important. So with me,
when I had that dodgy aortic valve, a bicuspit valve,
(10:07):
what that meant was every time that blood pumped out
of the left ventricle, and because my valve didn't shut correctly,
over time, some of the blood came back in and
that stretched the left ventricle. Now I was lucky that
I caught it relatively early. If I'd have waited another
year eighteen months, my left ventricle would have got much
(10:30):
stiffer and also would have stretched to the point of
no return. And that's what we call heart failure. When
you hear of heart failure, that's what it is. You're
left ventricle is actually stretching to the part of no return,
and it gets really stiff and it just does not
work well. Now, what also happened in these people is
their stroke volume also went up. The amount of blood
(10:53):
that they could pump out with every heartbeat, right, which
is really important. The heart size actually increase, So this
is a physiological adaptation. And a result of all of
that is that the resting heart rate went down because
the heart, because it was more efficient, didn't have to
(11:13):
beat as often. In real terms, this meant that they
were fitter, they have more efficient and more youthful hearts.
And in the control group, they didn't have any change,
any positive change. In fact, their heart function decline because
remember this is a two year study and they were
two years older and they had that two years of decline.
(11:35):
So let's break this down really simply in Layman's terms. So,
when your heart becomes stiff, that left ventricular stiffness, it
loses its ability to relax and fill with blood efficiently.
That is a direct pathway to heart failure with preserved
dejection fraction. That's what we talk about, and that's an
increasingly common and stubborn form of heart failure, especially and
(12:00):
older adults. And here's the kicker that twenty eighteen studies
showed that this trajectory is not inevitable. If you intervene
in middle age, you can stop this stiffness from setting
in the heart remains plastic or changeable into your fifties
and beyond. Now, the same research group did another study
(12:23):
where they took people in their sixties and they trained them,
and they didn't see the same results, right, So part
of that conclusion was you got to get on this
when you're in their fifties. But actually, when you look
into the detail, they did admit that the training intervention
that they did in the sixties wasn't as comprehensive as
the training intervention in the fifties. So there's still a
(12:45):
little bit of a question. But what we do though
is as your heart ages, it like all tissues in
the body, they lose their elasticity, right, So what does
this mean. It means that a couple of things. Number One,
your heart remembers. It remembers that three weeks of doing
nothing can wreck you more than three decades of aging.
(13:09):
So we have to be moving if we want to
have a healthy heart. But it also means that consistent
smart exercise, especially when it includes a mix of baseline
aerobic zone two and high intensity interval training that doesn't
just increase your fitness. This is about cardiac uth. It's
about making your heart younger, and if your heart gives up,
(13:33):
it's all over, right, And we're not talking about marathons here, right.
That twenty eighteen study met the public health guidelines right,
one hundred and fifty to three hundred minutes a week,
with some of it high intensity interval trainings and strength training.
I think that's also important in this study. It is achievable,
it is sustainable, but you've got to do the work.
(13:54):
That's the key thing. So the big take home here
is if you're in your forties and your fifties, or
you're guiding or know somebody is, this is the moment
to get on top of this because the longer you wait,
the harder it actually becomes. And if you're younger, don't
be complacent because your heart can age really really quickly
(14:16):
with lack of movement. In the end, your heart actually
wants and needs to be challenged. It was built to
respond and it responds to your environment. If you do
very little, your heart age is super super quick. But
if you actually do do the training, your heart will
respond and it will get and can get younger, and
(14:40):
you just have to give it the right kind of push.
And I'll leave you with probably my favorite quote of
any research journal I've ever read, from the Journal of
Applied Physiology in twenty twelve by Professor Frank Booth, legendary
exercise physiologist. He said, the human genome has not changed
(15:00):
in over forty five thousand years. Their current human genome
requires and expects us to be highly physically active for
normal functioning, and that is certainly the case for the heart.
Catch you next time.
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