[Angela Foster] (0:00 - 21:00)
Your heart starts ageing earlier than you think. Between the ages of 35 and 50, your heart becomes stiffer. Between 50 and 65, it actually gets smaller.

That might sound alarming, but here's the good news. Research has shown that the right type of exercise can reverse almost 20 years of cardiac ageing. Now, most people hear that and assume they need to spend hours running, cycling, or slogging away on the treadmill every week.

You don't. In fact, if you're a busy woman over 40 who's juggling work, family, and everything else that life throws at you, you can dramatically improve your cardiovascular fitness, your energy, and your long-term health in as little as 20 to 45 minutes, provided you're training the right way. And that's exactly what we're going to cover today.

By the end of this video, you'll understand the different training zones and why you don't need to spend hours each week. I'll also share how to get the biggest return on your cardiovascular fitness for your time invested. A lot of women come to me saying, Angela, I'm exercising more than ever, but I still feel exhausted, or I'm doing tonnes of cardio, but my fitness doesn't seem to be improving, or I just don't have an hour every day to spend exercising.

And I completely get it. We're told that if we want better health, more energy, and a healthier heart, we need to do more exercise. But the science tells a much more interesting story.

It's not just how much you exercise, it's how you exercise. Because every time your heart rate increases, your body is creating adaptations. But some intensities drive results in one area more than the other.

So understanding them is key, especially if like me, you want to save time. Some heart rate zones improve recovery, some improve endurance, some build your aerobic fitness and VO2 max, some stimulate your mitochondria to become healthier and more efficient, and some simply leaving you feeling tired without giving you as much return. So if you've ever felt like you're working incredibly hard, but not seeing the results you expected, there's a good chance you're simply spending too much time in a particular training zone.

Before I dive into any technicalities, we need to understand the bigger picture first. There are broadly five heart rate zones, and each one has a different purpose. Think of them as five different gears in a car.

You wouldn't drive everywhere in first gear. You wouldn't drive everywhere in fifth gear either. The same is true for exercise.

So if you only ever train at one intensity, you're only really developing one part of your physiology. So how do you know what zone you're exercising in? The easiest way is to estimate your maximum heart rate, and that would be a calculation of 220 minus your age.

It's not perfect, and if you've had a proper VO2 max assessment, that will give you a much more accurate number. But for most people, this is a perfectly reasonable and easy place to start. So let's now start with zone one.

This is around 50 to 60 percent of the maximum heart rate you just calculated. Think things like gentle walking, walking the dog, a relaxed hike. You're breathing normally.

You could hold a conversation without thinking about it. Many people dismiss this zone because it doesn't feel like exercise, but that would be a mistake because zone one improves circulation. It helps your nervous system recover.

It reduces stress. It increases blood flow to your muscles. It helps you recover better from your harder sessions, and for many women in perimenopause, particularly those who are feeling overwhelmed, burnt out, or constantly wired but tired, this is one of the most important training zones there is.

I do this regularly myself. If I spend hours recording podcasts or sitting in meetings, one of the first things I do is just go outside and walk. I know that I come back feeling clearer, calmer, and with far more energy than I had before I left.

So sometimes the best recovery isn't a supplement or something else. It's just simply a walk. The next zone we come to is zone two, and this is where things start to get interesting.

Zone two is generally around 60 to 70 percent of your maximum heart rate, and a simple way to estimate the top of your zone two is using the formula 180 minus your age. Again, this isn't perfect, but it gives you a really good idea, and the easiest way to know whether you're there is something called the talk test. You should be able to speak in full sentences, but only just.

If we were walking together, you'd be able to answer my questions, but I would know you were exercising. Your breathing would be noticeably deeper, but you wouldn't be gasping for air. That's zone two.

For some people, that's a brisk walk. For others, it might be a gentle jog. The important thing isn't the speed.

It's the effort. So in reality, your zone two is going to be unique to you, and that's determined by your physiology and fitness, not by your pace. The talk test is enough for most people to get started, and it's exactly how I recommend people begin.

That's how I started too, but as I became more intentional about my training and I wanted to be more precise, I started using the Morpheus heart rate monitor, and that's something I use with many of my coaching clients as well. I don't have any commercial relationship with Morpheus. I'm simply sharing what's worked well for me and for many of my clients.

What I like about it is that it doesn't just calculate heart rate zones from a generic formula. Every morning, it measures my heart rate variability, or HRV, which is one of the best indicators we have of how recovered and ready our body is to train. Morpheus also looks at my resting heart rate, my sleep metrics, and just as importantly, how I actually feel.

And I saw from yesterday's strength session, do I feel well recovered? Morpheus combines all of that information to personalise my training zones for that day, and that matters because your physiology will change from day to day. If you slept badly, you're under more stress, or you're still recovering from a hard workout, your heart rate is often a little bit higher for the same workload.

And without realising it, you can drift out of zone two into a higher training zone than you intended. It's not something to get hung up about, but on the other hand, when you're well recovered, you'll often be able to stay in zone two at a faster pace or a higher workload for longer. And I find that level of personalisation incredibly helpful, because it means I'm training the system that I want to train that day, rather than simply chasing a number on my wearable.

It also adjusts my recommended training zones over time as my fitness changes. So the guidance evolves with me rather than staying fixed. And I found that enormously helpful for improving my aerobic fitness, lowering my resting heart rate and increasing my heart rate variability.

And I've seen really great improvements with many of my clients too. None of this means you need to wear a wearable to get the benefits, you absolutely don't. The torque test works brilliantly for most people, but if you enjoy using data to personalise your training and make sure you're working at the right intensity on the right day, is one of my favourite tools because it adapts to your physiology rather than expecting your physiology to kind of fit into a generic formula.

So getting back to zone two, why has it become so popular? Because this is where your body becomes incredibly efficient at producing energy aerobically, is where your mitochondria, the tiny energy producing structures inside almost every cell in your body become healthier and more efficient. Think of mitochondria, like little power stations, every heartbeat, every thought, every muscle contraction, every hormone you produce and every repair your body carries out depends on them producing energy.

The healthier they are, the better your body functions, the less healthy they are, the more fatigue you tend to experience. And as we age, particularly through perimenopause, we lose some mitochondria efficiency. They become less effective at producing energy.

And that's one of the reasons so many women tell me, I don't feel like myself anymore. They're sleeping, they're eating well, they're trying to exercise, yet it feels like someone has turned down their battery. Now, of course, hormones, sleep, nutrition, iron status and thyroid function all play a role too.

It's never just one thing, but improving mitochondrial function is one of the most powerful levers we have for increasing energy naturally. And that's one reason zone two has become so popular. The other reason is that improves something called metabolic flexibility.

Metabolic flexibility is your body's ability to switch efficiently between burning fat and burning carbohydrates, depending on what it needs. Think of it like a hybrid car. Sometimes it uses petrol, sometimes electricity, and it switches effortlessly between the two.

Your body should work in much the same way. At lower intensities, you should be able to rely largely on fat for fuel. And then as the intensity increases, you naturally shift towards using more carbohydrate.

The problem is that many people lose that flexibility and they become much more dependent on carbohydrates, even during relatively easy exercise. This doesn't mean carbohydrates are bad, far from it. Carbohydrates are an incredibly important fuel source, especially for higher intensity exercise and helping you recover faster.

So the goal isn't to stop using carbohydrates. The goal is to become really good at using both fats and carbs. And that's what's known as metabolic flexibility.

And zone two is one of the best ways to improve it. Now, here's the thing that surprises a lot of people. You don't need to spend 90 minutes doing zone two.

That's become one of the biggest misconceptions online. When people first hear about zone two, they often assume that they need to spend hours every week walking on a treadmill or cycling slowly. The evidence doesn't support that for most people.

At around 20 minutes, you start seeing measurable improvements in insulin sensitivity. Insulin sensitivity naturally declines as you move through perimenopause. And when that happens, blood sugar regulation becomes less efficient.

Energy becomes more variable, weight management often becomes harder, and many women notice more brain fog and those familiar afternoon energy crashes. Improving insulin sensitivity helps address those things. By around 30 to 45 minutes, another really exciting adaptation begins.

Your body starts producing more mitochondria. This process is called mitochondrial biogenesis. So instead of simply making the mitochondria you already have work harder, which is great, you're actually encouraging yourselves to build more of them.

So think of it like adding extra engines to an aircraft. Suddenly you've got much greater capacity to produce energy. And for many women, that's when they begin to notice improvements in stamina, recovery, and day-to-day energy.

By around 45 minutes, fat oxidation becomes even more efficient. But there's a really important distinction here. Just because you're burning more fat during exercise doesn't automatically mean you're losing body fat.

They're not the same thing. Body fat loss still depends on your overall energy balance and your metabolic health. So Zone 2 isn't some kind of magic fat loss workout, but it's much more valuable than that.

It's helping you build the engine that supports your health, your fitness, and your energy for decades to come. And it helps you get more efficient at burning fat as a fuel and improving metabolic flexibility. Right now, you're probably thinking, the answer is simple, just go and do lots of Zone 2.

And that's what many people believe. But that's not actually what produces the biggest improvements in heart health. One of the most important cardiovascular studies ever published used something quite different.

It combined Zone 2 with a very specific type of interval training, and the results were really extraordinary. The participants didn't just become fitter, their hearts became structurally younger. So what I'm going to do next is show you exactly what they did, why it worked, and how you can adapt it safely if you're in your 40s, 50s, or beyond.

So researchers wanted to answer a simple question. Can you actually reverse the normal ageing process of the heart? We know that as we get older, the heart becomes stiffer.

It doesn't fill with blood as efficiently, and gradually it loses some of its elasticity. For years, many people assumed this was simply an unavoidable part of ageing. But the researchers wondered whether that was really true, or whether the right type of exercise could actually reverse some of those changes.

So they recruited previously sedentary adults in middle age, and they put them through a carefully designed training programme. The programme combined steady aerobic training with one higher intensity interval session each week. The interval session followed what's known as the Norwegian 4x4 protocol, and the results were really remarkable.

After two years, the participants' hearts have become significantly more compliant. That meant that they were less stiff and more efficient at pumping blood. Their VO2 max increased by around 18%, and the researchers concluded that their heart structure and function had improved to resemble that of someone almost 20 years younger.

Now that's an extraordinary finding. People hear that and they think, right, I'm just going to jump into doing Norwegian 4x4 intervals tomorrow. But that's not what happened in the study.

The participants didn't jump straight into that high intensity exercise. They spent months progressively building their fitness before reaching the full programme. And our bodies adapt incredibly well to progressive overload when we build up gradually, but they don't respond as well by doing too much too soon or with too little recovery.

So whenever you're doing a training programme like this, you want to monitor your recovery metrics, including your sleep, your resting heart rate, and your HRV. You also want to build up a baseline fitness using zones like zone 1 and 2 before you start engaging in the Norwegian 4x4 if you're a beginner. So let me explain the Norwegian 4x4.

After a proper warm-up, you work at around 85% to 95% of your maximum heart rate for 4 minutes. That's hard enough that it's going to be virtually impossible for you to hold a conversation. You're breathing really heavily and you're working hard.

Then you recover for 3 minutes at an easy pace before repeating that cycle 4 times. The intervals themselves add up to 28 minutes, and with a warm-up and cool-down, the whole session takes around 40 minutes. For something that can produce such profound improvements in cardiovascular fitness, that is an incredible return on your investment of time.

Now you might be wondering why combining these harder intervals with zone 2 works so well. The answer is that each intensity creates a different adaptation. Zone 2 is building the foundation.

It improves your aerobic engine, it supports your mitochondrial function, and it helps your body become more efficient at producing energy. High intensity intervals build on that foundation by pushing your cardiovascular system close to its capacity. They stimulate improvements in VO2 max, increase stroke volume, improve your ability to deliver oxygen to your muscles, and create a really powerful signal for your body to adapt.

So if you think of it like building a house, zone 2 is laying the foundations, and then higher intensity training is building the upper floors. So neither one is superior to the other, they're doing different jobs, but together they're more effective than either one alone. There's another reason this combination works so well, especially for women in midlife.

We often hear that we should avoid anything that raises cortisol, and it's true that a hard interval session will temporarily increase cortisol because exercise itself is a stressor, but that's not necessarily a bad thing. A healthy body doesn't avoid stress completely, it learns to adapt to it, and when you recover well those short bursts of stress actually make you more resilient. Over time, your cardiovascular fitness improves, your recovery improves, and your ability to tolerate both physical and psychological stress improves as well.

The zone 2 work helps with recovery, increasing nutrient delivery and blood flow to your muscles, which is why they work so well together. One thing to bear in mind with exercise selection is if you're already exhausted, burnt out, sleeping badly, or you're feeling consistently overwhelmed, don't start with the Norwegian 4x4. I would suggest you start by rebuilding your capacity first, so prioritise sleep, strength training, walking, really healthy nutrition, and adding in enough recovery.

Then add in some zone 2 work and let your nervous system settle, and then once you've rebuilt that foundation, you can progressively introduce the higher intensity work. That's exactly what happened in the study, they earned the right to train hard by first building the capacity to tolerate it. And that's probably the biggest takeaway from all of this.

The question isn't whether zone 2 is better than intervals or whether intervals are better than zone 2. The real question is whether you're using each type of training at the right time, in the right amount, for the stage that you're in. Because when you do that, you're not just going to improve your fitness, you'll be improving your energy, your metabolic health, your resilience, and ultimately the way your heart ages.

Once you're in a good spot managing stress and recovery load, and you've built that foundation, if you're short on time, instead of doing long zone 2 sessions, do one Norwegian 4x4 workout per week, plus two to three strength training sessions. By skipping the long cardio sessions, you can get some really good results in less time. You also don't have to find a big block of time to see the cardiovascular benefits.

There's something else I want to share that you can actually integrate into your day, and this is called Vigorous Intensive Lifestyle Physical Activity, or VILPA. This is when you take everyday activities and you make them more intense. And four minutes a day of VILPA reduces all-cause mortality by between 26 to 34 percent.

16 minutes per day of VILPA reduces all-cause mortality by 43 to 55 percent. Which is really remarkable. So think about what this means for your daily life.

We're not talking about structured workouts here, this is about doing things that you would do anyway. So instead of walking up the stairs, you run up the stairs. You do 15 squats while your coffee's brewing, or you sprint for 20 seconds on a stationary bike between meetings, or on your lunch break.

These tiny little things really actually improve your health over time. And the step data is equally compelling, but again, you don't have to do as many as you've probably been told. 10,000 steps is not a magic number.

In fact, going from 2,000 steps per day to 8,300 steps reduces your risk of all-cause mortality by 60 percent. And the science shows you get an additional 5 percent reduction going from 8,000 to 16,000 steps. So don't sweat the extra steps.

Focus on getting to 8,000 steps, which is doable for most people. You can take calls while walking, use a bathroom on a different floor, park further away. Just adapting your lifestyle with simple things like this adds up your steps over time.

The other thing about body weight squats I want to mention is they improve glucose regulation, in some cases more effectively than walking. So doing them after meals is great. I tested this myself with a glucose monitor, and I found better results when I did them slowly and really focused on contracting my glutes, rather than doing them quickly.

So I would say for best results, don't rush them. The mechanical tension and the time under tension matters more than the speed, it seems. You can also microdose your workouts.

My husband does this because he's often short on time before work, and the science actually backs it up. Nine 15-minute sessions per week, done once or twice daily, produces the same strength and endurance improvements as three 45-minute sessions. And this can be really helpful, especially if you have a busy schedule like many of us do.

So to leave you with some practical things you can start doing, this week, identify three everyday movements where you can add some intensity. So run up the stairs instead of walking. Do 15 squats when your coffee's brewing.

Sprint for 20 seconds on a stationary bike in between meetings. Add these to your calendar and then commit to doing them. These small bursts reduce mortality risk and improve glucose control without requiring you to carve out huge blocks of time.

Don't put pressure on yourself to do everything I've mentioned in this video. Look at the season of life you're in. If you've got kids, work and limited time, your approach is going to be different than somebody who has more flexibility.

The goal is to integrate what you can actually do and then establish consistency, not perfection. Here's an example of a sustainable framework that I use. So walk for a per week.

Break it into 20 to 30-minute sessions. These are going to really add up across the week. Go out with your dog if you have one.

Take a call while you're walking or get off a stop early on your commute. Don't worry about the heart rate zone you're in. This is just helping with overall blood flow, nervous system balance and health.

Then do one zone two session per week. This can be 30 minutes or up to 45 minutes. And then finally, add one high-intensity session per week.

You could do the Norwegian 4x4 or something similar. In terms of your muscles, which I've done separate videos on, you want to look at resistance training your full body two or three times a week. This entire workout routine pretty much covers all your bases and that will involve a maximum of about six hours per week, which when we have 168 hours in our week, this is literally only about three and a half percent of your time across the week.

And if you add in some movement snacks throughout the day by setting a reminder on your phone, this is going to produce some really, really good results for you for a minimal time commitment. The sooner you start doing this type of training and movement integrated into your day, the easier it is to slow ageing. So the best time to start is definitely today.

But bear in mind that without exercise between 35 and 50, the heart is starting to stiffen and between 50 and 65, it shrinks. But what matters most is that you get started. Progressive training works better than jumping straight into high volume.

And in the study that showed that 20-year heart reversal, participants spent around six months progressively building up to their full training load. So don't try and suddenly do everything at once. That would be a recipe for injury and burnout.

And the other thing to say is medical clearance always matters, especially before doing high intensity work. If you're wondering where to begin, I've created an energy and resilience quiz. It's completely free to help you establish your baseline.

In just a couple of minutes, I'll identify the biggest areas that may be holding back your energy, fitness, and resilience, and you'll get personalised recommendations on where to focus first. It's a really simple way to understand where you are today so you can start building a healthier, more resilient future. I'll put a link in the description.

Remember, the remarkable thing is that no matter your starting point, you still have an extraordinary opportunity to influence the way your body is ageing. So start small, be consistent, and that's when you'll see some results. Thanks so much for watching and I'll see you in the next video.

Your heart is ageing faster than you think. It stiffens between 35 and 50, and shrinks between 50 and 65. For years this was written off as an unavoidable part of getting older. It isn't.The right type of exercise has been shown to reverse almost 20 years of cardiac ageing, and it takes far less time than you've been told.

If you're exercising more than ever but still feel exhausted, or pouring hours into cardio with nothing to show for it, this episode explains what's really happening in your heart, your mitochondria and your metabolism after 40, and the exact way to train smarter, not longer.

WHAT YOU'LL LEARN

- Why is my heart ageing faster after 40 and can I reverse it?

- Why do I feel tired but wired in perimenopause?

- What is metabolic flexibility and why do I lose it after 40?

- How little zone two exercise do I actually need to see results?

- What is the Norwegian 4x4 protocol and is it safe for women over 40?

- Do I really need 10,000 steps a day?

- How do squats after meals improve blood sugar and lower mortality risk?