Exorcist, or Exercise: what's healthier?
Dave Ansell - To start off with, we've got an experiment which is going to take a while and we need a volunteer, somebody who's feeling really energetic this morning, this evening.
Chris Smith - And knows what time of day is, Dave.
Dave - Which I obviously don't. You look like you're very keen, would you like to come up?
Ginny Smith - Can everyone give him a round of applause please? What's your name?
Younas - Younas
Ginny - Younas and where have you come from today? Where do you live?
Younas - Here in Cambridge.
Ginny - In Cambridge, brilliant. Now, we're going to get you to do a little bit of exercise today during the show. So, what do you want him to do, Dave?
Dave - So, what I've got over here is a generator. It's got a handle on it and when you wind the handle, you produce some power. At the moment, that's rigged to just heat up some air, so you're going to be warming up the room for us a bit. But I'm going to work at how much energy you've used in that time and convert that to chocolate bars. Okay, so we're going to get you winding that handle for about 10 minutes and see how many chocolate bars you've burnt. So, do you want to start winding the handle for me, at a speed which you think you can keep up for a while. That's brilliant and yep he's generating about 10, 15 watts of power at the moment which is pretty good going. We'll leave you going Younas for a bit and we'll come back to you later.
Ginny - So, on the screen, I can see a whole load of different numbers but on the left hand side, can you see that it says Mars bars? So, that's how much of a Mars bar he's burning. So, we're going to watch that number and see how many Mars bars he earns in the course of this experiment.
Chris - Are you feeling tired yet?
Younas - No.
Chris - He says no. Give it 10 minutes or so. Well, let's talk to Dan Gordon because you ought to tell people, you have quite a good track record in sport . Tell people what you do.
Dan - That's quite a good pun. Yeah, I was an international track cyclist. I used to race tandems on the velodrome. So, that banked cycling track, but rather than use just one person on a bike, we had two.
Chris - Isn't that cheating?
Dan - Yes, it is slightly. It was quite good, I got to put my feet up on the back and the guy at the front just pedalled really.
Chris - But did you get any records?
Dan - Yeah, I held two world records and I still hold one world record.
Chris - Which one?
Dan - I hold the world record for a kilometre outdoors which has stood since 2003.
Chris - Wow! He's got to get a clap for that, surely. Are you really nervous then every time the Olympics comes around? Are you thinking, "Oh no! They might get my record"?
Dan - No. I get quite anxious actually and particularly in London, a lot of the guys racing, are the guys I used to race with. In fact, the guy I used to ride the tandem is still racing. It's quite hard to be sitting on the other side of the barrier and I've got kind of itchy feet, particularly with about 4 months to go and I did announce to my wife that I thought I might make a comeback. I got shouted down very quickly, but yeah. I'm not worried about the record going. That's what they're there for.
Chris - So, how fast are you going on those bikes?
Dan - For the kilometre time trial, it's about 60 km an hour. So, in old money it's about 43 miles an hour.
Chris - 43 miles an hour. That's amazing, isn't it? Is that what inspired you to become an exercise physiologist or were you already a scientist?
Dan - I was already a scientist at the same time so I was very fortunate that I'd actually retired from athletics. I'm going to show off now, I was an international athlete, I did track and field internationally and I retired, and then saw an advert saying, "Have a go at tandem cycling." So, I was working at the same time. So, it's been quite nice. I've been able to tie my sport with my profession. It's been really quite fulfilling in that sense.
Chris - So, what are you trying to understand when you do experiments on people? What questions are you asking?
Dan - Well, the questions I'm asking in the research is, what limits our ability to use oxygen. If you think what we're doing now, we're all sitting here and especially the young chap who is doing the exercise in the corner, we're having to use oxygen. We are, by definition, what's called aerobic. We use oxygen because oxygen is the primary fuel currency. If you think about the way he's turning that crank, his muscles are lengthening and shortening. What we want to know is what limits that upper ability to do that. There's a point where you cannot provide enough oxygen to meet the demand. There's a huge debate about, is it limited in terms of, it has something to do with the heart? Because if you think what the heart does, it pumps all that oxygenated blood to the muscles and so on, or is it a limitation at the muscle. And so, the experiments that we're doing are really to find out where that limitation sits and is it different for example between somebody who's highly trained, maybe a Bradley Wiggins, to somebody who is untrained or sedentary. Then once we understand the mechanisms, we can then start to actually understand the underlying pathologies and so on behind it.
Chris - Are you the only athlete in your family or does this run in your family?
Dan - The genetic question. My father was a cyclist and that's not why I fell into cycling. I was a typical, "If he does cycling, I'm not going to do cycling." Why would you? So yeah, he was a cyclist but he had trials with Aston Villa and so on. So, there is kind of a sporting heritage I suppose, yeah.
Chris - Shall we just catch up on how we're doing on the cranking because we've nearly burned 1/500 of a Mars bar?
Ginny - So, how are you feeling?
Younas - Fine
Ginny - Is anything hurting? Are you feeling tired at all?
Younas - A bit.
Ginny - A bit, and where's it feeling tired?
Younas - Here.
Ginny - In your arms. Okay, so your arms are working really, really hard and that's where they're feeling tired.
Dave - How much of a Mars bar does it feel like you've actually worked off so far?
Younas - Two?
Ginny - Two whole Mars bars but in fact, you can see on the screen, it's 0.0027. So, we're nowhere near a Mars bar, let alone two. Why does it feel like you're burning off so much more than you actually are?
Dan - Well, it's a jolly good question in many ways. In this little experiment, you've hit on two major themes. One is, exercise hurts, and that's one of the big reasons that we get significant dropout rates in terms of exercise because actually, there's a huge discomfort with it. The second thing is, unfortunately, genetically, we're not very well built. If you think...
Chris - Thanks very much.
Dan - But apart for some of us anyway. If you think about the way those muscles are lengthening and shortening, and he's got a great pair of guns the way he's turning that. But they're lengthening and shortening and he's providing the oxygen, but what's happening is, for the muscles to lengthen and shorten, you have to use a chemical in the muscle and that chemical is called adenosine triphosphate. Sounds really technical, it's nothing particularly clever. But the key point is, in order use that ATP, we have to get the energy from it and we use water. Simplest process ever, it's hydrolysis. In that process, we generate heat and actually, this is the problem. We actually lose 70% of that energy in the form of heat. So we're actually, only about 30% efficient. So, at some point, the government will tax us because we're producing all this adverse heat. That is why it actually tends to feel harder because actually, we're not mechanically very efficient at doing this, any form of exercise, and particularly, when it's something like that that you're not used to doing.
Chris - So, going back to my question about your family. Does it mean then that some people are better at coping with these situations or have better ways biochemically of preventing this problem?
Dan - Yes. There's a number of camps on this, but there is no doubt, there's a genetic predisposition to being able to do exercise. We know that there are certain genes that seem to describe whether you are an endurance athlete, whether you are maybe a high jumper. But we also are starting to recognise now that there are genes that actually describe why people don't respond to exercise. I'm sure everybody is suddenly going, "Well, this explains everything. That's why I don't go to the gym." And we're starting to understand - it's about 1 in 10 - that's a quite high number - would potentially be a non-responder to cardiovascular exercise which is the predominant form of exercise we talk about in terms of maintaining a healthy lifestyle. I say to my students, "If you're not an Olympic athlete, it's very simple. Just blame your parents" because that's really the backdrop to everything you do. You're working within the genes that you're given.
Chris - Anyone here got some good genes for exercise? Have we got any athletes in the audience? Are you an athlete?
Fergal - Very much an amateur athlete.
Chris - What's your event?
Fergal - Well, I row and I run.
Chris - What's your name?
Fergal - I'm Fergal.
Chris - Any questions for someone who's a professional in this? How you can make your amateur turn professional?
Fergal - Well I'd love to know, is there a correlation between fitness and VO2 max and fitness and heart rate because I know myself. I have a really low maximum heart rate, but my resting heart rate is quite low. But my maximum heart rate is about 170. I just wondered why that is.
Chris - Maybe you should start by telling people what VO2 max is.
Dan - Yeah and actually, it's interesting because that's actually where my research is. VO2 max is what it says. It's the maximum volume (V for volume) the maximum volume of oxygen that you can take up from the air and use for the generation of energy. So, how much oxygen, there's a point where, it doesn't matter how much you take in, you can't use it. This is the primary way we assess people's cardio, respiratory fitness and to put into context, how do we do it? Pretend to put somebody on treadmill. We make them run and we make the gradient go steeper and steeper, and steeper, until they can't run. We measure the expired air and we can calculate O2 and CO2. Really, in relation in terms of VO2 max to describe fitness, it describes for cardiorespiratory fitness and cardiovascular fitness. So, we know that the best endurance athletes typically have higher VO2 max scores. The other question was about heart rate. Heart rate is a really interesting one because the perception is, that if you get cardiovascularly fitter, then you'll start to see a decrease in your resting heart rate. That's correct and we know that Tour de France cyclist can tend to have resting heart rates of about 28 beats per minute.
Chris - Normal of course, being about 70, isn't it?
Dan - Normal being around 70 beats per minute, so, it's incredibly low. But there's a paradoxical response because the general conception is that if you're exercising and you want the heart to pump that blood to the exercising limb, you'd expect the maximal heart rate to increase, it doesn't. The maximal heart rate starts to decrease and the reason for that is, if you think about the experiments going on in the corner, so the poor chap is still going.
Chris - Hang on. Younas, how are you getting on?
Younas - I'm exhausted!
Chris - This poor guy has been turning this crank Dave has given him, continuously throughout this evening's event. You've burned off 0.0049, so, nearly, 0.005 of a Mars bar. Well done!
Dave - I guess to be fair to him that he has actually burnt off probably three times that amount of energy because his muscles aren't very efficient, so he's probably burnt of 1 1/2 % of a Mars bar in 10 minutes.
Chris - Would you like to stop?
Younas - Yes.
Chris - Give him a round of applause. Well done.
Dan - So, the bit we were discussing and just mentioning was the fact ironically, that the maximum heart rate decreases. The way to think about it is that the heart itself is a muscle. What happens is, as you start to train, rather than having it beating faster and faster, and a great example is Younas doing that exercise, his muscles are getting tired. You don't want your heart getting tired. You imagine going out for a run and going, "My heart is tired. I can't exercise!" so, what happens is that the heart muscle, just like someone that goes to the gym, gets bigger, gets thicker, the cavity in the heart, the ventricle gets wider. So actually, what happens is, per beat of the heart, you can eject more blood per beat of the heart, which means you can now get more oxygen to the muscle. So, the adaptation is, the fact you're saying you've got a lower maximal heart rate is actually, I'd take that as quite a good sign. That's quite a good indication that endurance training is working.
Chris - What's your name?
Carlo - I'm Carlo from Cambridge. When you run uphill on a mountain, you tend to go out of breath quite easily. When you come down instead, your muscles still hurt, but your breath is okay. So, what's the difference between the work you do when you go uphill and the work you do when you do downhill?
Dan - That is a great question. Okay, so if you're going up a hill, and of course, that's a perfect question for in Cambridge, isn't it? But if you imagine running up a hill, what's happening is, and it's the exact same as we had in the experiment is that as that hill is steep, the amount of oxygen you're taking in, it's struggling to meet the demand. So, what happens is, in the muscles, you start to use an alternate energy source. You start to borrow energy and you're borrowing it from a source which is called anaerobic energy. The by-product of which is this chemical called lactic acid. This is what you start to feel and this is coupled with carbon dioxide and this is why you start to become breathless. When you go downhill, although you're perhaps running quicker, because you're running downhill, the way in which your muscles are moving is very different. Because what you're trying to do is, now you're trying to apply a brake. So, when you're going up the hill, the majority of the work is actually happening because the muscle is shortening. When you're coming down the hill, the muscle is acting as a brake. In other words, it's actually lengthening. This is the really cool biological adaptation. If a muscle is lengthening, it uses almost no energy. Think of a spring. So, if you've got a spring and it's sitting on the desk and you put your hand on it, you push the spring down, you're putting energy into it. It's like the muscle shortening. If it lengthens, all you've got to do is take your hand away and it springs back. There's no energy being imparted into the spring and that's the way the muscle works. So actually, although you're running at a similar speed, you're using less metabolic energy and actually, you start to recover.
Chris - You're listening to the Naked Scientists with Chris Smith and Dave Ansell, and Ginny Smith, and our panel of esteemed guests. We're answering the questions of the audience here. Give yourselves a round of applause. Ginny, what have you got coming in on the electronic routes of communication.
Ginny - So, I've got a message here from Vanessa on Twitter who asks, "Can increasing physical fitness directly improve cognitive ability, assuming other variables are constant?" And that's something I've heard as well. If you keep fit, it doesn't just do your body good. It does your brain good as well.
Dan - Yes, it's the adage is that we're all taught as kids, a healthy a healthy mind. I'm not entirely sure whether I see it in my students. But there is certainly good evidence for this, that we know one of the things we get. We get a release of what are called endorphins in the brain and actually, this starts to bring about positive sensations. There are adverse effects as well. So we know that if we look at games like soccer - I'm going to call it soccer. I know it offends people - and you look at when most mistakes are made in the game. Most mistakes are made, anybody want to take a guess?
Male - When England play?
Dan - Yes, absolutely. But they're made in the last 10 minutes of a game. What we know is, that there's a relationship between the number of mistakes being made and how tired somebody is getting. In other words, there's a link between a physical fatigue and cognitive ability. If you want to win a marathon race and everybody is together, the best time to actually make the attack and really go for it is in the latter stages because mentally, people are less competent because of physical fatigue.
Ginny - Actually, I've got a question that I wanted to ask. So, I've been reading a lot about this high intensity interval training recently. The idea that you can do just 30 seconds of really intense exercise and get the same benefits as going to the gym for half an hour. Is there any evidence behind that?
Dan - There's no doubt. I mean, you could sit here as a scientist and go of course, there's loads of evidence. The issue is, who does the evidence fit? So, the idea is that in this day and age, we haven't got enough time to exercise. So, it's more beneficial if you do 3 high intensity burst of 30 seconds exercise than going to do half an hour. There's plenty of data that shows this. The issue that I have as a scientist with this is, the studies have only ever been performed on physically active, highly trained individuals who can tolerate it. It's incredibly hard to ask somebody to work maximally for 30 seconds, have a couple of minutes rest and then do it again, and do that 4 times, and do that 3 times a week. When you apply it to the population that it was meant to fit, which is our sedentary population who were maybe the more obese population, they can't tolerate it. We have a mismatch between what the scientists are suggesting and it's perhaps you could argue slightly spurious in terms of the way they've communicated the information and actually, the way in which it can be applied to the more general population.
Chris - Anyone got any other questions for Dan? One over the back...
Julian - My name is Julian. I'm from Cambridge. I've actually got two questions. Firstly, we hear about fast twitch and slow twitch muscles. I assume that the fast ones twitch quickly and the slow ones slowly. But what's the actual difference between those two muscles? And then secondly, how quick is our 100 metres record going to go. What do you think the fastest we can ever do will be?
Dan - Wow! Okay, we'll start with the easy one. So, fast twitch, slow twitch, yeah. We've got two broad categories of muscle fibre. If you look under the microscope at them, they do look distinctly different. A slow twitch fibre under the microscope actually has a very red colour to it. And a fast twitch fibre has very white colour. Those of you that like to eat meat, if you look at chicken, it's white. Think about what a chicken does. It flaps its wings really fast. If you think about a cow, cows don't move very fast. It's red meat. Why? The red muscle is oxygenated muscle. It has to have a blood supply to it and it's very rich in oxygen, it has lots of capillaries which allows the oxygenated blood to get to them. A fast twitch fibre, which is kind of Usain Bolt fibre, those fibres, they don't need the blood supply. Why? Because the energy is stored directly in the muscle. There's not a lot of it, but the energy in the muscle then can be used instantly for what's referred to as a much more explosive work that you couldn't use a slow twitch fibre for. The second question is, how quick can we ever get in the 100 metres. This is kind of how long is the piece of string question, isn't it? This is kind of dodgy water. Projections are, that within the next 10 years, you could see a 100 metres run at 9.3.
Chris - Usain Bolt told Richard Bacon on the BBC Radio 5 Live Bacon Show when asked, "What did you eat before your 100-metre dash?" He said, "Cheeseburger and chips." Would you recommend that diet? Is that a good Olympic record-breaking diet? Is that what you used to have?
Dan - Well, it's odd isn't it? It's going to be slightly - again, slightly dodgy water to get into. For a 100-metre race, if I'm brutally honest, before a 100-metre race, it makes no odds what you eat. It makes no difference at all. If you were dealing with an endurance athlete then I would say, the worst thing you could've done is eaten that. His race is over in 10 seconds. He's using energy that is stored in the muscle.
Chris - What's your name?
Paul - Hi. I'm Paul from Cambridge. So, we're learning this evening that increasing your heart rate is very good, healthy, improves your stamina, general fitness and health. If I'm watching a horror movie, I tend to find my heart rate increases. What's the scientific benefit of say, The Exorcist compared to Nightmare on Elm Street?
Chris - Better still, can we substitute one for the other?
Dan - Yeah, I mean, there is a difference. There is a difference between what is in essence a more stress orientated response and what is much more a physical orientated response. Although we are raising the heart rate under those stress conditions, there are actually more adverse conditions because what you're doing is you're raising the heart rate but you're also raising blood pressure. That's why you get that classic stress response. What you want under exercise conditions is you want the heart rate raised but actually, you want to be burning energy. So, you want the muscles to be lengthening and shortening. So, the answer isn't, I'm afraid, to sit and watch very bad horror films.
Chris - It's a shame isn't it? I know we let Younas off a bit early because he was looking like he was about to die. But you better explain what actually did you find out of this experiment, Dave and Ginny?
Dave - I guess this sort of brings out the point, I really don't think that Younas would've wanted to burn off a whole Mars bar like that. So, why does exercise actually cause people to lose weight if actually, the actual energy compared to food you eat is tiny?
Dan - Yeah, I mean, it is one of the great questions really. We have to recognise, when we're talking about healthy lifestyle, it's not just about the exercise. It is a combination of exercise plus diet, plus actually, just generally looking after yourself. The key with exercise and this comes back to the question Ginny asked as well. Is actually doing it at the right intensity. We have to understand that what we're trying to target when we exercise is we're trying to burn, breakdown fat. So, you've got to exercise long enough that you start to metabolise and break this fat down. He did 10 minutes worth of work, we have to actually make sure the intensity is right and we actually have to make sure the duration is right in order to metabolise enough that we start to get the benefits. It starts to become cumulative. So a one off session, you're not going to get suddenly become very fit. But the adaptations, which is what we're after, this loss of fats and all these lovely physical gains we're talking about, it's a cumulative response. As you start to exercise, you will suddenly realise, "Actually, rather than go for 10 minutes, I can go for 12 minutes." There's been very small cellular adaptations in the cell right inside those cells, there's what's called a mitochondria and the mitochondria is where respiration in the cell takes place. We know that the mitochondria start to increase in their number in size as you start to train. That means you become more efficient at using the oxygen that we started talking about earlier on, so you can go a little bit further, and a little bit further. So, it's these very small adaptations that produce in the end, these bigger gains.
Ginny - So Younas, you'll have to come back again next week and do it again, it sounds like. He doesn't look too happy about that.
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