It's Madeleine here with my podcast co-host and guardian science editor, Ian Sample. Hello, Ian. Hello. We've received loads of brilliant questions from you about how to get moving and how to stick to it in 2025. And last episode, we heard how to look after our immune system, something that I probably need to go and re-listen to, as well as all you need to know about seed oils.
Now, we've done our research and spoken to the experts, so today we're exploring everything from what's the best kind of exercise for somebody with limited time, what we should be eating and when to maximise the benefits of our workouts, and how we can all stay active as we age. So, let's get started. From the Guardian, I'm Madeline Finley, and this is Science Weekly.
Ian, we had a few listeners get in touch with their questions about exercise guidelines, so starting off with the absolute basics. What are the current recommendations for how much exercise we should all be getting?
So they vary a little bit on your age. I'll give you the guidelines for sort of the bulk of adults and 19 to 64-year-olds. They don't vary that wildly outside of those age ranges, to be honest. Now, the caveat sports exercise people will always say to you high up is talk to your GP if you've not been active for a while, or if you have like a medical condition that could make exercise particularly risky for you. But ideally, you want to be looking at
doing strengthening exercises at least two days a week, and they need to target those major muscle groups, and you want to be doing aerobic fitness, so moderate intensity activity for two and a half hours a week, or half that 75 minutes of vigorous intensive activity. Essentially, you know, moderate exercise might be walking or riding a bike fairly leisurely, vigorous exercise is going to be
running, cycling up hills, doing aerobics and things like that. Okay, so these guidelines sound reasonably comprehensive, but listener Aaron got in touch to ask something that I hadn't thought about before, which is who the researchers or public health experts had in mind when they created the guidelines. So here he is.
Hello Science Weekly, my name is Aaron and I have a question about the general recommendations for the amount of time we just spent exercising every day a week. Where did these come from and who did they use for these studies? Should these recommendations vary for people of different ethnicity or any other factors? For example, as a non-white person myself, my assumption is that these recommendations are probably not as applicable to me, but I'd love to know if I'm wrong. Thank you.
So Ian, what do we know about who these guidelines are based on and whether they should vary for different ethnicities? So first of all, where do these guidelines come from? They are based on a lot of studies on the general population. Now, that is obviously a mix of ethnicities and so on. And these studies come from many different countries and they get pulled together. But the studies we're talking about are
epidemiological studies that look at what sort of diseases, what sort of health outcomes do you see in people who do different levels of activity, different levels of physical activity. So, for example, you might look over a 20-year period and see what the death rates are for people who exercise for two hours a week compared to those who don't do any exercise for a week.
Those are the sorts of studies that really lead health officials to these pretty consistent, actually, these pretty consistent guidelines that we see around the world. But to Aaron's second point about whether these guidelines should vary for different ethnicities, I called up Jason Gill. He's Professor of Cardio Metabolic Health at the University of Glasgow, and he's published research on exactly this area.
We've done work and others have as well to show that there are differences between people. So, for example, we have shown that people from South Asian ethnic origin are on average, a little bit less fit, have a lower level of cardiovascular respiratory fitness than people are white European. There is huge overlap in the bell distributions, but on average slightly less fit and also slightly less strong.
And because we know that fitness and strength are important, the evidence suggests that people from a South Asian background might need to do a little bit more physical activity to get to a similar level of benefit overall from people of white European background.
And we've done some work to suggest that rather than 150 minutes of modern density physical activity, it might be a little bit higher. So in the low 200, so maybe 230 to 250 minutes. But the key thing here is any activity you do is good, more is better. It's just the point to get to where we think is the optimal level might be slightly higher for some people than others.
So it seems to be little differences like that that are affecting the kinds of exercise and the amounts of exercise that people may need to be doing to sort of achieve the same fitness results.
so interesting. Now earlier when you were talking about the guidelines you set out the ones that were from 19 to 64 and there are slightly different ones above and below those ages and a couple of listeners in the older age bracket got in touch and were after some specific advice so I'll hand over to listener Santosh.
Hello Science Weekly. My question relates to running. Should heart rate targets be lowered or maintained as one ages? And how should one tell a high intensity exercise during aging to avoid injury or potentially placing undue stress on the heart? And the further question relating to the heart is can the heart deal with pumping at say 90 to 95% of HR max when the person is 50 to 60 years old as opposed to say a 25 or 30 year old?
And this is something Jason Gill at Glasgow talked about. So as we get older,
on maximum heart rate falls. So if you take a 20 year old, they might be able to have a maximum heart rate of about 200 beats per minute. As you get older, that falls off at about 0.72, 0.8 beats per year. So when you get to age 60, the maximum heart rate you can reach might be in the 160s or 170 beats per minute. Again, there's huge variability in this. So don't worry if the number that you can get to is loads higher or loads lower than that, but generally it goes down a bit over age.
The evidence suggests that the heart is a muscle and like all other muscles, you have to use it or lose it. So as you get older, it's important to keep up doing harder work that's getting your heart to be faster, to be able to keep the capacity to actually do that hard work.
If you're somebody who regularly exercises and has been doing it for a long time, you can work up to whatever level feels comfortable. You don't really need to worry about that number. If you are somebody who's not being active for a while,
It's probably sensible to start off for maybe the first six months or so, working at a more moderate intensity, and then over time, gradually do the harder sessions. If you've done nothing at all, first session back at age 60, do some sprinting, that's probably not sensible. But if you're somebody who's regularly active, then we absolutely should be doing this work at higher intensities to actually maintain our fitness as we get older.
And we had a similar question from Mike who wanted to know how to approach strength training as he ages. And he says, I read a lot about strength training to build muscle being important as you get older. However, most books seem to be written for 20 year olds.
They often recommend three or four training sessions a week. However, 50 I find I need longer recovery time, often three days of sore muscles after a session. So what's best? Should I be doing two sessions a week and feeling sore every day? Or should I push through and do four sessions a week? And frankly, still we saw.
Yeah, so for this one, we talked to Benjamin Wall, who's Professor of Nutritional Psychology at the University of Exeter, and he had some pragmatic advice for Mike.
When it comes to the type of exercise, strength training, you would get different views on this, but my personal view would be that it's probably the best modality of exercise you can do because it combats most of the problems that we see in the musculoskeletal system that we are all susceptible to as we inevitably go through the aging process. That is the loss of muscle mass.
loss of muscle strength, balance, bone density, etc. So strength training is highly effective at this. In terms of how best to optimise that strength training to get to the main point of the question, my practical advice here would be to exercise
to the point where you feel like you've had a great workout and then come back again when you feel you've recovered. If that is fewer sessions than you've read in terms of advice for a 20 year old, then so be it. I suspect those advantages are still being gained in that time in between those sessions.
Ian, that takes us on to the type of exercise that we should be doing. And we had quite a few listeners getting touch about this. First of all, we heard from a GP who said that he wanted to give his patients simple and easy to follow advice about exercise. You know, he knows a lot of them don't have much time. And I'm sure lots of us can relate to that. And
He also asks whether any forms of exercise are considered superior when it comes to keeping all of our muscles strong. So what do we know about that?
Well, for this one, I went to I'm in Lee, who is a professor of medicine at Harvard Medical School. And she said, look, I don't believe there is one best exercise because we're such varied individuals. For her, the best exercise is the one that the person likes doing, whether it's gardening, dancing, or walking the dog.
It's just important that it's something they will stick with over the long term. Now, look, swimming is great, but there are people who hate the water or hate the cold water or they don't have access to a pool. So for them, sure, it's not for them, but it's more about what is the exercise that you can do and that you will keep doing. And she says, look, there is such a large body of evidence that shows that any exercise is good. So her advice is just do it.
I like that answer. It's a bit like everyone's a winner, as long as you're keeping active. And staying with the theme of not having lots of time to devote to exercise, listener Mattanne got in touch too.
My question is, what is the most time-efficient way to exercise? I am a father of a three-year-old and I work full-time and I don't have much time or energy to get into shape. I've heard about high interval training, but I can't bring myself to do it. Specifically, I'm wondering, is building up muscles the best thing to do because then they might work for me even when I'm not actually using them? But I don't know.
would love to know the answer. So we know that ideally Matan would be combining both cardio and strength training and that this can be stuff that he builds into his normal routine, like you said, like carrying shopping or making sure he's using the stairs, cycling where he can. But to his second point, is he right to think that he can build muscle that will keep quote unquote, sort of working for him even when he's not exercising?
What I think Mattan is asking is if you build up more muscle, does that muscle then help you burn calories more effectively? I think that's what he means by this idea of will those muscles keep working for him when he's not exercising? And I asked Jason Gill for his take on this.
So if you do resistance type exercise, so exercise where you're, you're lifting heavy things and it doesn't necessarily need to be weights. It can be bands or body weight. What you're going to do is increase your muscle mass a bit. And what happens is that muscles working all the time, all the time it's burning calories. So if you have more muscle, there's more review that requires
energy over the whole day. So the muscle is, in essence, working for you the whole time. You're building it while you're doing the exercise session, but because the muscle there and needs fuels to function for the rest of the day, the muscle is working for you at all times.
So Ian, we've heard how much exercise we should all be aiming for and what kind of exercise can be most effective. But we also had some questions from listeners about which kinds of foods should be powering all this exercise. The first one is one I think lots of people will be interested in and it comes from Charlotte.
High Science Weekly team. So there's a lot of different advice out there about what types of nutrients we should eat, X amount of time before or after we exercise. And I'm wondering whether any of it really makes enough of a difference that we should be worrying about it. And if it does, then which of the many different recommendations should we be following?
You know, this is something I've wondered about as well because if I go for a run or I go to the gym, I like to do it on an empty stomach. But then once I'm done, I'm really hungry, but you know, you don't necessarily want to eat straight after you've done some exercise. So when is the best time for us to eat around exercise and what should we be eating?
So for this one, I got in touch with Clyde Williams, who is Emeritus Professor of Sports Science at Loughborough University. And he said that extreme dietary behavior isn't necessary for someone who's simply going along to the gym to keep fit. But he said it is worth paying attention to your food intake after a gym session. And he mentioned having a carbohydrate snack or a drink,
that will help replace the muscle glycogen used in your training session. He also said that a post-exercise tuner or ham sandwich couldn't sort of help make sure there's enough protein available to begin the repair of this exercise-induced muscle damage that your session will have sort of incurred on your body. But he says, look, you know, unless it's been a really long training session or has involved very heavy lifting,
There's no need to do things like, you know, protein shakes directly after you've left the gym. The usual sort of recommendations really are sort of whole grains, high fiber, starchy carbohydrates, lean proteins, fruit and veg. They're all going to make sure you have the energy to put your all into your workout and help you recover afterwards so that you're then ready for the next session.
Okay, so that takes us on to the more specific topic of protein intake, and specifically for vegans, listener Sandra got in touch to say, I'm a vegan, I'm working out and my trainer has told me to eat more protein to build up muscles. The aim is to eat 120 grams of protein per day, but she says that she hardly manages to get to 80.
You know, how much tofu beans does she have to eat and she wonders how others do this? So, what do we know about how important it is to stick to a set level of protein in order to build up muscle?
I ran this one past Clive Williams at Loughborough and he said, look, to answer this question properly, I'd really need to know something about Sandra and things like, you know, what weight she is and what she's looking to achieve through exercise. And he said, you know, roughly speaking, you want to be
consuming about 1.2 to 1.5 grams of protein per kilo of body weight for endurance running or cycling. If you're doing power sports or on a strength training program, that rises to 1.5 to 2 grams per kilo.
And he said, OK, let's just guess and suppose Sandra's around 70 kilos. If she's consuming 80 grams of protein a day, she's not far off that 1.2 grams per kilo. So that's enough for sort of general fitness and even an endurance runner or cyclist.
He said, there are protein powders that you can eat with your meals to increase your protein intake. If you're finding it difficult to do it through just the normal foods you consume, although he said it might be tough finding vegan versions of those. He said an alternative might be to eat nuts throughout the day to help boost your protein intake over the day.
Talking of that, he said that protein intake should be spread through the day rather than eat an all-in-one go as an evening meal, for example, because you need time for digestion and for assimilation of the amino acids after each meal.
And Sandra mentioned some particularly healthy sources of protein, beans and tofu. But when you go into the shops these days, there are all kinds of protein-based products. So are there any sources of vegan protein that are deemed superior? This is something Benjamin Wall at Exeter talked about.
It's a really good question because this is probably the buzz topic in this field at the moment where the protein comes from for multiple sort of ethical environmental lifestyle issues. The literature's moved on in the last five years or so to suggest that there are plenty of vegan proteins that are of sufficient quality that you can actually hit those targets relatively easily.
All the studies that have now compared vegan protein consumption to animal protein on training studies generally show that the adaptive response is the same in both of those conditions. So I think most of the typical things that vegans would be advised to eat in terms of soy protein, pea protein, tofu.
And some of the more alternative ones like protein derived from fungi, micro proteins, and increasingly some even wackier ones like protein derived from algae are also showing that they're just as good as taking high quality animal proteins. So I think the vegan athlete does have a few more options open to them. And I also ran these questions past Victoria Taylor and she's the head of clinical support at the British Heart Foundation.
She said you shouldn't just assume that sort of all vegetarian or vegan options are going to be healthy. The sort of mock meats you can get, the nuggets, the veggie burgers, the veggie hot dogs. Yes, they contain protein, but they can also be loaded with salt, high-end fat and saturated fat and calories. And so you don't want to just be assuming that
because an option is vegan or vegetarian, it is a healthy thing for you to be eating. So as well as looking at the protein content, look at everything else that's going into that meal as well before you go for it.
That's really good advice because I think sometimes there is a bit of misunderstanding between being healthy and being vegan and sometimes those two things can be conflated. So Ian, this has all been super interesting. I'm a touch annoyed that rowing wasn't named as the best sport because I do roe, but I'm glad that if it works for me, I'm good. So thank you so much. Not at all, Maddie, you're welcome.
Another big thanks to Ian, to all the experts we spoke to and of course to you, the listeners for all your brilliant questions. And if you enjoyed this episode and have a moment to spare, it would be great if you could leave us a review wherever you're listening. We really appreciate it.
And that's it for today. This episode was produced by Tom Glasser. It was sound designed by Tony Onachuku, and the executive producer is Elie Bure. We'll be back on Tuesday. See you then.
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