Lesson video

Hello there, and welcome to today's lesson.

My name is Mr. Swaithes, and I'm really looking forward to teaching you today.

So in today's lesson, we're gonna look at the differences between aerobic and anaerobic exercise.

Have you heard those terms before? And have you ever figured out the difference between the two and perhaps which exercises in sports rely predominantly on one versus the other? So today's lesson is called Aerobic and Anaerobic Exercise, and it comes from the Unit Anatomy and Physiology: Anaerobic and Aerobic Exercise.

By the end of today's lesson, you'll be able to apply knowledge of aerobic and anaerobic exercise to various sporting examples.

The keywords for today's lesson are aerobic work or aerobic exercise, anaerobic work or anaerobic exercise, lactic acid, and lactate accumulation.

You might want to pause the video for a moment and make a note of these definitions, but we'll be revisiting them during the lesson.

Today's lesson is broken up into two parts.

The first part will look at the difference between aerobic and anaerobic, and then into the second part it'll become more applied, where we'll look at examples of those aerobic and anaerobic exercise in action.

So, what do you know about this already? Well, our bodies need energy, don't they? And when we exercise, more energy is needed to be supplied to and enable muscular contractions to occur.

This energy comes from the food we eat, i.

e.

glucose, and the air that we breathe, i.

e.

oxygen.

So they're the two compounds that we need.

Glucose or long chains of glucose are called glycogen, and air, or oxygen specifically from the air is the substrate that we need.

Depending on how hard or how intensively we exercise energy will be provided either aerobically or anaerobically.

Which way round is it? Can you think? When you exercise at a really high intensity, is that aerobic or anaerobic exercise? Let's do a quick check before we find out.

So, which of the following is not a source of energy? Is it oxygen, glucose or muscles.

Which is not a source of energy? That's right.

Muscles are not a source of energy.

They require energy in order to contract providing movement.

Okay then, so aerobic work is when you are working at a moderate intensity so that the body has time to utilise oxygen for energy production, allowing the body to work for a continuous period of time.

For example, long distance events or last in the duration of a football, or a rugby, or a netball match.

So aerobic work or aerobic exercise is that exercise that's at a moderate intensity and that enables us to keep going for a long time because we're using oxygen to provide the energy for exercise.

In contrast, if we want to create more explosive and powerful muscular contractions, we need to do so anaerobically.

So therefore, anaerobic work is at high intensity without oxygen for energy production, therefore limited energy so the work period will be short.

Yeah, so if we're working anaerobically, we can only do that for a short period of time because of the way that energy is provided.

Which is why if you are sprinting, you are limited for how long you can sprint for.

You couldn't, for example, sprint a marathon.

So sprinting up the wing in a game of football, or maybe sprinting up a hill would be a great example of anaerobic exercise in action.

So anaerobic exercise means that insufficient oxygen is being supplied to the muscles due to that very high intensity of exercise over a short period of time.

So you still supply oxygen to your muscles, but there's insufficient quantities of it to do that complete breakdown of the glucose in your muscles.

Sprinting up a hill, as I said, is a great example.

And this results in the production of lactic acid, which causes muscular fatigue.

So you know that you are working anaerobically, if you get that burning, aching feeling in your muscles, and you are forced to slow down 'cause of course that's what fatigue is, isn't it? It's when your body can't keep going, you reach exhaustion, you need to slow down or maybe even stop.

When there's that shortfall in oxygen, I.

e.

you are working at a higher intensity, it results in lactic acid buildup because that's a byproduct of energy production that is anaerobic.

And during recovery, we need to repay that oxygen debt.

So we need to give it back to the muscles and that's why often we're left out of breath after hard exercise.

So think of the last time you perhaps did a hundred metre sprint and you maybe would've coped with not breathing too much during the race, but at the end of the race, you are super out of breath trying to repay that oxygen debt and get rid of the lactic acid that's accumulated in your muscles.

So a quick check, true or false? In simple terms, anaerobic means using oxygen.

Is that true or false? That's right, it's false.

And can you tell me why? Yeah, so aerobic exercise is in the presence of oxygen, whereas anaerobic is at a higher intensity and hence without sufficient oxygen for the complete breakdown of glucose.

A nice easy way to remember that is aerobic uses air, specifically the oxygen in the air.

Okay, so if aerobic respiration occurs when glucose and oxygen are combined to provide energy for exercise, here's an example of someone going for a walk, that will definitely be aerobic respiration in action.

Which helpful to look at this simple formula to help us understand what's going on in terms of chemistry in the body.

So glucose plus oxygen is converted into carbon dioxide or CO2, plus H2O or water plus energy.

So when we use glucose and oxygen and we combine them in the muscle cell, they provide energy for movement with the byproducts of carbon dioxide and water.

If you go for a walk, that's a great example of aerobic exercise.

So I wonder, do you know what happens as intensity increases? So if you turn that walk into a jog and then into a run, and then perhaps into a sprint.

Well, during very low intensity exercise you can burn fats as well as carbohydrates or glucose.

So that's why perhaps you've seen in the gym on perhaps the treadmill, you'll see a fat burning zone.

So if you are operating at a low intensity, so for example at a low heart rate, you'll find that you can burn fats as well as carbohydrates.

And the harder you work, the more you'll just be burning carbohydrates.

And then if you increase your intensity even further, things change again.

So a long distance jog is another example of aerobic exercise.

Well, what happens if you run even faster? Or if you exercise an even higher intensity? Well, let's jump to the very other end of the spectrum for a moment.

And anaerobic exercise is where it's a very high intensity and short duration.

So for example, lifting this really heavy weight would use anaerobic respiration, where carbohydrates are the fuel source for this.

And a simple formula for what's going on here at the muscle site, is that glucose without oxygen this time is being converted into energy for exercise, but has a negative of the creation of this lactic acid.

So in fact, it's an incomplete breakdown of the glucose which results in this lactic acid buildup in the muscles.

And, of course, lactic acid is a fatiguing byproduct.

So power lifting or 100 metre sprint, they're great examples of anaerobic exercise.

Can you think of any other examples? Okay, so let's leave that into our first task for today's lesson.

Can you define and explain the difference between aerobic and anaerobic exercise? And then secondly, can you provide and explain a simple formula for aerobic and one for anaerobic respiration? Pause the video now whilst you do that and come back to me when you are ready.

Well done.

So let's have a little look.

You may have said for part one of this, that aerobic exercises with oxygen, that's the key word you need in there.

And it's to provide energy for low to moderate intensity activity like walking and jogging.

You can last a really long time when you're performing aerobic exercise or aerobic work.

Whereas anaerobic exercise is at a higher intensity and hence provides energy without oxygen, or more specifically without sufficient oxygen for activities like sprinting.

But there is an incomplete breakdown of glucose that results in lactic acid buildup and that's why we need to repay that oxygen debt during recovery.

I.

e.

, we keep breathing, we stay outta breath after high intensity exercise, and more so than if we've done low intensity excise.

And important to remember you can only last a short duration at this high intensity before fatigue sets in.

Into the second part of this question then, I was asking you to replicate those simple formula.

So you might have said that for aerobic respiration, what's going on here is, glucose + oxygen converts into carbon dioxide plus water + energy.

You could put those different parts in any order.

So you might say goes to energy plus CO2 plus water.

Or use chemical formula like CO2 and H2O.

So just a quick reminder that O2 is oxygen, CO2 is carbon dioxide, and H2O is water, of course.

And then for anaerobic respiration, we've got glucose without oxygen being converted into energy for movement + lactic acid.

And remember that partial breakdown of glucose occurs if not enough oxygen is present.

And this results in that production of lactic acid, which is a fatiguing byproduct, will eventually cause you to need to slow down or stop.

Okay, that brings us nicely into the second part of today's lesson, where we're gonna look at some examples of aerobic and anaerobic activity in action.

So, do you know who this is? That's right.

It's Kipchoge.

So with the support of a team of pacemakers and sports scientists, Kipchoge broke the two hour marathon in 2019, an enormous feat.

So it was a record that we thought was never gonna get broken.

So covering that marathon in just under two hours.

So to achieve that, he maintained an average pace of just over four and a half minute miles.

Crazy speeds.

That means an average of just over 17 seconds to cover 100 metres.

And I don't know about you, but for a lot of us, just sprinting 100 metres in 17 seconds is hard work, let alone keeping that going for a whole 26.

2 miles, i.

e, a whole marathon distance.

And in fact, the keyword there that I said I would need to sprint in order to achieve a 17 second, 100 metre would suggest I have no hope of covering that whole marathon at that pace 'cause you cannot sprint for a really long distance.

You can only run.

Because sprinting is high intensity, hence anaerobic.

So how can he manage that then? As Andeep says, "How is that even possible?" And Laura's wondering, "Could you match that pace even for just 100 metres?" I challenge you to have a go next time you're on an athletics lesson.

Could you do 100 metres at 17 seconds? Can you go faster than that? Or how many 17 second, 100 metres could you string together and keep going for? Could you manage four for example? So a full lap of 400 metre track.

And the big question there then is, was Kipchoge working aerobically or anaerobically when he achieved that? Well, let's have a quick check before we delve back into that to understand it fully.

So which of the following are examples of anaerobic exercise? A tackle in rugby, a Tour de France stage, or 100 metre sprint? Which of those are anaerobic i.

e.

high intensity? That's right, A and C are definitely at that high intensity level.

And for the Tour de France cyclists, there will be elements of high intensity to that race.

But in order to last the whole day and the multiple days, it needs to be working aerobically the majority of the time.

So anaerobic respiration produces a lot of energy really quickly.

That's great for explosive muscular contractions, for example, this hurdler.

But it's got a downside, hasn't it? Lactic acid is produced.

What happens if you produce a lot of lactic acid? Do you know? And can you think of other activities that result in this too? So we've got hurdling, what else typically results in lots of lactic acid production? Well, let's take it back to Kipchoge.

So in this example, we're looking at an elite endurance athlete who trains to work at that anaerobic threshold.

So they're working just at that tipping point between am I providing enough oxygen to keep working aerobically, and to not build up too much lactic acid, or have I crossed that threshold, I'm building up lactic acid and I'll fatigue and need to slow down and stop.

So when you're at that anaerobic threshold, if you can stay just inside the aerobic zone, it prevents building up too much lactic acid.

So whilst you'll be building it up, you're able to get rid of it just fast enough to prevent fatigue.

So what would've happened then if Kipchoge had tried to run a little bit faster at the start of the race? I wonder, can you figure that out? Well, let's give another example to try and help you.

So similar to running and cycling, when is rowing aerobic and when is it anaerobic? Well, if you need to last over 60 seconds in any event, the predominant energy system must be aerobic respiration.

So the answer to this question is rowing would be aerobic or predominantly aerobic if the race lasts more than 60 seconds.

But even in endurance events, we often put in that sprint finish, which would be anaerobic.

But if we go too soon or too fast, then we fatigue.

And that's what links back to that Kipchoge example.

So had he started out too fast too soon, he would've crossed that anaerobic threshold built up lactic acid, and what we say is he'd have hit the wall, he would've needed to slow down or stop.

And that's because of this lactate accumulation.

So that's the point at which lactate levels in the blood and in the muscles rise steeply due to increased work intensity.

And it's actually when they cross this threshold of four millimoles per litre of blood that it becomes problematic for the human body.

So when we can only last a short period of time when we're working anaerobically, that means that we've crossed that threshold.

So if you're doing exercise and you're like, I can't keep going at this pace, at this intensity, then you must be working anaerobically.

And anaerobically for you, might be different to me, and certainly will be different to Kipchoge who has a very high threshold.

Another check then, which of the following are examples of aerobic exercise? Is it A, throwing javelin, B, that Tour de France stage cyclist, or C, a recreational swim.

Which is aerobic? That's right.

The Tour de France stage and the recreational swim are both aerobic or typically aerobic.

Now, let's look at the swimmer.

And, of course, swimming can be performed at a very high intensity, and certainly if you're not a very good swimmer, you'll find it is exhausting and you probably are working anaerobically.

Or maybe, if you try to swim butterfly, a really explosive stroke that would be anaerobic.

But this example of a lap swimming, recreational swimming, is more leisurely and it's over a longer duration.

Hence, we are calling it aerobic in this example.

So this is why you must be really specific over the intensity and the duration when you're saying this is aerobic or this is anaerobic.

So it's aerobic, if it's low intensity, high duration.

It's anaerobic, if it's high intensity, low duration.

Let's look at this hockey player.

So most games require a mix of aerobic and anaerobic respiration.

So when you sprint after a ball, you'll be working anaerobically, high intensity.

You can't sprint for that long though, can you? Because lactic acid builds up and that will cause fatigue.

So that's why in order to last the whole match, you will also have lower intensity periods where energy comes from aerobic respiration and you are repaying that oxygen debt that built up when you sprint it.

Okay, that brings us into the second task for today's lesson.

So I'd like you to identify three examples of aerobic activities.

Remember, to identify why they are aerobics, we've talk about intensity and duration.

And then three examples of anaerobic activities.

Again, talk about intensity and duration.

And then finally, can you think of two examples of activities or sports that utilise both aerobic and anaerobic energy systems and explain when and why they use these different energy systems. Pause the video now whilst you do that and come back to me when you are ready.

Well done, so let's have a little look at those first two questions.

So aerobic activities you might have put walking, jogging, long distance running, or long distance cycling, or long distance swimming or rowing.

Any of those are correct if you've talked about low intensity, long duration.

Whereas, these are examples of anaerobic activities.

So the 100 metre sprint, power lifting, throwing a javelin, serving in tennis, or tackle in rugby, a spike in volleyball, and the list goes on.

But it's important you've selected things that are really high intensity and a short duration.

Typically, we use examples that last perhaps up to 10 seconds.

And then I ask you to think about activities or sports that utilise both energy systems and to explain when you move between those different energy systems. So here's an example.

You might set a game of rugby uses aerobic respiration during those slow periods of play and to last the whole 80 minute match, but when you make tackles or you're involved in a scrum or sprinting for a try, you'll be using the anaerobic energy system because they're high intensity bouts.

Or maybe you said, a game of tennis uses aerobic respiration to play those long rallies and to last the whole match, and a whole match, as we know, can last hours at the top level.

But explosive muscular contractions like a serve and a sprint to the net for a volley would use anaerobic respiration to provide that energy without oxygen.

You may have come up with plenty of other examples, but as long as you've talked about the intensity and when it's high intensity, it's anaerobic.

And when it's low intensity and longer duration, it is aerobic.

Well done today.

So that gives me time to just quickly summarise the lesson on aerobic and anaerobic exercise.

So aerobic exercise is working at a moderate intensity, so the body has time to utilise oxygen for energy production.

You're allowing the body to work for a continuous period, for example, long distance events, or the whole duration of perhaps a match, a football game.

Anaerobic exercise is working at a higher intensity without oxygen for energy production.

So therefore, limited energy.

So the work period will be shorter.

E.

g.

sprinting up the wing in a football match or maybe sprinting up a hill.

And we also talked about the different formula, didn't we? How aerobic exercises, glucose + oxygen converts into carbon dioxide plus water plus energy.

Whereas anaerobic exercise, we have glucose converting into energy + lactic acid.

And here we have lactic acid and it's that byproduct of energy production that builds up during anaerobic exercise, causes fatigue and will force you to slow down or stop.

Once that lactate accumulation in the blood reaches a certain threshold, which is why I couldn't go for a long distance run with Kipchoge, 'cause my lactate accumulation would cross that level and he'd keep going and I'd need to stop, probably after about 200 metres, given that he can run 100 metres in 17 seconds and keep going at that pace for a whole marathon.

I hope you've enjoyed today's lesson and I look forward to seeing you again next time.