Lesson video

Hi there, welcome to today's lesson.

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

So, this lesson is all about the immediate, i.

e.

, the minute you start exercising, and then short term, i.

e.

very soon after you've exercised, so perhaps in the next 36 hours, what happens to the body.

So a lot of you will know already that as you start to exercise, your body needs to respond to try and get it in a state to cope better with exercise, and you probably also have experienced some of the soreness, perhaps the next day after you've done a heavy exercise session.

So that's what we're gonna explore in today's lesson, and it comes from the Anatomy and Physiology, the Short- and Long-Term Effects of Exercise unit.

This lesson is called "Immediate and Short-Term Effects of Exercise on the Body." By the end of today's lesson, you're gonna be able to identify the immediate and the short-term effects of exercise on the human body.

The keywords for today's lesson are obviously immediate effects of exercise, those are the ones that occur the moment you start exercising, the short-term effects of exercise, so these are the ones that you'll perhaps feel over the next 12 to 36 hours after exercise.

We're also gonna be looking at fatigue, DOMS, which might be a new term to you, so Delayed Onset of Muscle Soreness, but I bet you've felt it before, and cramp.

We've broken up the lesson for you into four parts, so the first part we'll look at the immediate effects on the muscular system, then the second part the immediate effects on the cardiovascular system, the third part the immediate effects on the respiratory system, and then finally we'll be looking at some of those short term effects that you feel and that last about 36 hours, depending on how hard your training session was.

I hope you're ready, let's get going.

So, when we start exercising there are a number of immediate changes that happen at the muscular system, so we're focusing in now on the muscular system specifically, and Lucas is wondering can you name and describe any of these changes? Well, let's summarise some of them then.

So, we've got an increased demand for oxygen in your body, we'll also have an increased production of carbon dioxide, and in a minute, we'll explore why those two things are happening.

You'll have increased production of lactic acid which will cause muscular fatigue, and that happens particularly during a certain sort of exercise, and then finally you'll have an increased muscle temperature, and again we'll unpick in a moment why that happens from a biological standpoint.

So, let's do a quick check before we get into the detail.

Which of the following is not a response to exercise that is related to the muscular system? Is it a, increased muscle temperature, b, increased lactic acid production at the muscles, is it c, increased carbon dioxide required by the muscles, or is it d, increased oxygen consumption by the working muscles? Which of those is incorrect? That's right it's c isn't it, because actually there's increased carbon dioxide produced by the muscles, not required, the muscles don't want it, they want oxygen.

So, Laura's wondering why is there an increased demand for oxygen at the muscles? Do you know? That's right, so aerobic respiration requires oxygen, and glucose actually, to provide the energy for exercise.

The more you exercise, and the harder you exercise, the more oxygen your muscles will require, and I'm sure you've experienced that haven't you? You start to run a little bit faster, and you get more out of breath, and that's because your body's trying to get more oxygen to your working muscles, and later on in this lesson we'll connect this to the respiratory system and the cardiovascular system, but at the moment we're focused in on the muscles and what's going on there.

So, exercise at a high intensity results in what we call oxygen debt, and that's got to be repaid after exercise, and I wonder if you've ever felt like you've perhaps gone for a run, and after you finish running you are still out of breath after that demand of exercise has finished, and we refer to that as oxygen debt, or repaying an oxygen debt.

Okay, Laura's also wondering then why is there an increased production of carbon dioxide at the muscles? Can you answer that one? That's right, so carbon dioxide is a waste product of that aerobic respiration that's happening in the mitochondria of the muscles.

So, the mitochondria is what's kind of called the power plant of the muscles, that's the location where this aerobic respiration takes place, and the harder you exercise the more carbon dioxide you will produce.

The muscular system needs to work really closely with the cardiovascular and the respiratory systems to transport oxygen to the muscles, and then get rid of carbon dioxide that the muscles are creating but don't want.

Next one from Laura then, she's got lots of questions today, hasn't she? So, she wants to know why is lactic acid produced at the muscles, and I wonder if you come across that term before, and you know why and when in what conditions lactic acid is produced? Okay, so it's a fatiguing byproduct, and it's a waste product that comes from anaerobic respiration, i.

e.

, working at a high intensity.

So if you were to go out for a really high intensity run, a great example of this is a 400 metre run actually because you're almost sprinting for as close to 60 seconds as you can, and what happens if you're trying to sprint, you're trying to work at too high an intensity, you can't deliver enough oxygen to your working muscles for them to work aerobically.

So, they'll work in part aerobically but also in part anaerobically, and that results in what we call lactate accumulation.

So, this build-up of lactic acid at the muscles that then spills out into the bloodstream, and if too much of this lactic acid builds up, we're forced to either slow down or in some instances stop exercising completely.

So, it's why it's important that you don't go off too fast in a race because once you've crossed that, what we call an onset of blood lactate accumulation, once you cross that, it's really hard to recover it and keep your pace of running or exercising.

Okay, so another question from Laura, why do muscles increase in temperature when we exercise? Got any idea on that one? That's right, so the chemical reactions that break down glucose and oxygen to give that energy for our muscles to contract also result in a lot of energy being released as heat.

So actually, our muscles and the human body in general is not a very effective thing, it's not a very efficient machine, and about 80% of that energy actually ends up getting released as heat.

If you imagine all of these little chemical reactions going on in your muscles to make them contract, some of that energy is going into the movement that happens and lots of it is just releasing heat, it's almost like fireworks going off inside your muscles, and that increases your muscle temperature, which is why on a cold day it's best to move more and faster because you'll generate heat, you'll warm yourself up.

So, as I've said, it's a bit like a firework going off inside the muscle.

We get red skin, and we sweat to help get rid of that excess heat, so we know when someone's exercising don't, we, because they perhaps are starting to perspire or sweat, and they're perhaps also, we can see that glowing look of more red skin.

We also get an increased blood flow to the muscles to supply more oxygen, and this increases the temperature further.

So, this is a process known as vasodilation of the blood vessels that are supplying blood to your working muscles, whilst there's some vasoconstriction of the blood vessels that are supplying other parts of the body that don't need that oxygen.

So, we call that the vascular shunt mechanism, or the redistribution of blood.

So, if we're gonna send more blood there, of course that increases the heat even further.

Okay, true or false then? A quick check.

Our muscles only get warmer if we are exercising in hot environments.

Is that true or false? That's right, it's false, but can you tell me why? Okay, so the chemical reactions that happen in our muscles to produce the energy for movement also give off an awful lot of heat.

About 80% of it actually is given off as heat, hence one of the best ways to warm up is to do some exercise.

But obviously if you are in a hot environment, you will get even hotter because it'll be even harder for you to cool your body down, which is why heat exhaustion is a real risk and endurance events that are done at a hot climate.

Okay, so that brings us to our first task of today's lesson.

I'd like you to describe two of the main changes that happen at the muscle site as a result of starting to exercise.

So, by that I mean the immediate effects of exercise on the muscular system.

And we've talked about four today, so I want you to remind yourself of two of them and describe them fully.

Pause the video whilst you do that and come back to me when you're ready.

If you really wanna go for it, why not do all four? Right then, let's compare your answer to mine.

So, hopefully, you selected that muscle temperature factor.

So, muscle temperature increases as a result of the chemical reactions taking place in the muscle that produce movement.

Secondly, we talked about how increased oxygen consumption, and that's required to provide energy for aerobic respiration.

Thirdly, we talked about how increased carbon dioxide is produced as a by-product of aerobic respiration.

And lastly, this is a popular one, I hope you wrote this one down, the increased lactic acid accumulation at the muscles as a consequence of high intensity exercise.

So, the lactic acid won't build up if you're only going for a gentle walk, or even maybe a jog it might not build up.

But it's when you start to exercise at a higher intensity that that lactic acid builds up.

And of course, it's a fatiguing by-product that will force you to either slow down or stop completely.

And I wonder if you've ever got that kind of jelly legs feeling, and that is lactic acid working its magic.

Okay, that takes us through to the second part of today's lesson then where we're gonna look at the cardiovascular responses to exercise.

So similarly, when we start to exercise there's a number of immediate changes that happen within the heart, the blood, and the vascular system.

Can you think of what any of them are? So, Lucas is wondering, can you describe any of these changes? Well, let's look at a quick summary.

I bet you thought of this one that your heart rate increases, and a little bit later we'll unpick why.

We also hope that you remember that you get hot, sweaty, and red skin.

There's an increase in your stroke volume.

Remember what stroke volume is.

There's an increased cardiac output.

Again, what's cardiac output all about? And finally, there's that redistribution of blood to your working muscles and also to your skin.

I mentioned that a moment ago about the vascular shunt mechanism.

So, Laura's wondering again, why do you get hot, sweaty, and red skin during exercise? Do you know? That's right, because exercise results in the production of lots of heat within the muscles.

That heat needs to be removed from the body to maintain homeostasis or thermoregulation, so to stay at that same core body temperature.

Consequently, our circulatory system, or our cardiovascular system responds by sweating and also by sending more blood to the surface of the skin.

So, you can see how what's going on at the muscular system is then transferred to some effects at the cardiovascular system as well.

So, they link really closely, don't they? Well, did you know that a typical teenager or adult has a resting heart rate of about 72 beats per minute? And in fact, anywhere in that range of kind of 60 to 100 beats per minute is normal.

Newborn babies have a much higher resting heart rate, by the way, and it slows down as we transition to being children and then to teenagers and then to adults.

And in general, as a person grows older, their heart rate slows down because their heart becomes more efficient and pumping blood and also a little bit less elastic, a little bit less able to beat so regularly.

So, Alex is wondering, what happens to your heart rate when you exercise? Aisha is asking, what about when you're sleeping? And what about if you're a super fit athlete? I wonder if you can answer a few check questions first.

So, can you recall what heart rate is measured in? That's right, it's beats per minute, isn't it? BPM.

And can you recall a typical range for resting heart rate? That's right, it's 72 beats per minute, although 60 to 100 beats per minute is perfectly normal.

And I often try to get mine below 60, my resting heart rate, because that demonstrates I've got fairly good aerobic fitness.

It suggests I'm quite healthy and well.

Okay, so the following factors increase your heart rate.

Physical activity or exercise, we know that, don't we? Adrenaline release due to stress, anxiety, or excitement, and we feel that butterfly in our stomach.

That's actually that adrenaline being released just prior to some sort of stressful situation.

It's the fight or flight response.

Coffee, stimulants, and some medications also increase your heart rate.

An increased body temperature leads to an increased heart rate.

Dehydration can also increase your heart rate because you'll end up with less blood volume circulating.

Illness causes your heart rate to go up, which is why doctors often measure your heart rate if you're in hospital.

So, Laura is wondering, why does she feel those butterflies before a race? Well, it's our fight or flight response, isn't it? And it kicks in before exercise to help prepare the body for that exercise.

Adrenaline is released as kind of an anticipatory response to the fact that exercise is about to happen.

So, if you're about to go and do a run, your body goes, oh, I know this is coming.

My brain is telling my body to start to prepare for that.

So, that anticipatory rise in heart rate by a few beats per minute, and sending a bit more blood to your working muscles helps already start to load more oxygen to your muscles.

So, your heart rate increases from 60 to 80, or 60 to 100 beats per minute up to a maximum of 220 minus your age, depending on the intensity of exercise.

So, you remember I said that your heart rate decreases a bit as you get older.

And a good rule of thumb is your maximum heart rate is 220 beats per minute minus your age.

So as a 40-year-old, your maximum heart rate would perhaps be about 180.

As a 16-year-old, you should be able to get your heart rate up to about 204 beats per minute.

So, let's have a little look at a graph then.

So, if I went out for a 12-minute run, my resting heart rate there is about 70 beats per minute at rest.

And then that anticipatory rise happens.

So, it kicks my heart rate up a little bit in response to the exercise.

Or actually, it's not in response to the exercise.

It's in response to my brain telling my body I'm about to exercise.

And then my increased heart rate continues to soar as I start to run.

And it does that until a point where the amount of oxygen I'm supplying to my muscles is sufficient for them to keep working aerobically.

And at that point, your heart rate will platter.

It will stay about the same level.

So, this is quite a gentle jog.

My heart rate at about 155 beats per minute.

And then you can see at 16 minutes on this video, sorry, on this graph.

So, the run started at four minutes.

It's lasted 12 minutes.

So, it finishes at 16 minutes.

And instead of the heart rate dropping straight back down to resting levels, the heart rate stays elevated for a little period of time.

And that is to repay that oxygen debt from the beginning.

And then it gets back to your resting heart rate.

So, Alex has got another question for us.

What would happen to your heart rate in a game of football? Maybe you could have a go at trying to plot one before I reveal mine.

I'm sure your graph looks completely different to this because it depends on what that player is doing in the football match.

But we can see the football match starts, I don't know, about eight minutes.

And where there's peaks in that graph, that would suggest perhaps sprinting, running after the ball.

And when it drops back down again, maybe this player is sort of resting a bit and waiting for the ball to come back towards their area of the pitch.

So, it's kind of a tooth saw graph that happens.

And actually, depending on your position, this would look quite different.

So, a goalkeeper's heart rate when they're standing when the ball's in the other end of the pitch might be lower.

A midfielder, they might have a higher heart rate for the whole duration of the game because they're far more involved in the play.

And again, maybe a striker might have a heart rate that plateaus a bit more often or drops down lower quite often if they're away from the periods of play.

And a lot of managers now and sports scientists in the professional football game will keep an eye on their players' heart rates to get a sense as to how hard they're working, but also how fatigued they are.

And that often leads to substitutions at the end of the game.

Okay, let's have another one from Alex N.

What would happen if you went out for a run, and you ran as hard as you could until exhaustion? Have a think about it.

We said, didn't we, maximum heart rate is 220 beats per minute.

So, let's imagine that you go out for a run, and you start off steady and you're increasing the intensity.

You're running faster and faster and faster and faster.

And when it gets to about 12 minutes, this runner has reached a point where they've hit their maximum heart rate, and that jelly legs feeling begins.

So, that lactic acid has built up to such a point that they're no longer able to carry on.

So, fatigue happens, forces that person to stop, and then that recovery heart rate would happen.

And that doesn't necessarily happen at 12 minutes.

I could reach fatigue in 60 seconds if I went out for an all-out sprint.

Obviously, I have to be careful I warm up first and not pull a hamstring muscle, but you can reach fatigue very quickly.

A rowing machine is a great example of an exercise that when I get on it, I reach exhaustion pretty quickly if I'm going at it.

Okay, Laura's got another question for us.

Why does our stroke volume increase during exercise? Well, our heart pumps more forcefully when we start to exercise.

We can feel our heart beating in our chest, can't we, during exercise.

And consequently, more blood is ejected from the ventricles per heartbeat.

So that means your stroke volume has increased.

Yeah, because stroke volume is the amount of blood ejected from the heart or ejected from the ventricle per beat.

So, if your stroke volume has increased, that will supply more blood, which means more oxygen and more nutrients to your working muscles.

And what about cardiac output then? Well, cardiac output is the amount of blood ejected from the heart in one minute.

It's calculated as heart rate multiplied by stroke volume.

So, if your resting cardiac output is about five litres per minute, this cardiac output increases because heart rate increases from perhaps 60, or 70 beats per minute and stroke volume increases from perhaps about 70 millilitres per beat.

And because both of those increase quite a lot, it can take your cardiac output during exercise up to an amazing 20 to 40 litres per minute.

So, 20 for someone who perhaps doesn't do much training, and some of the most endurance trained athletes like Tour de France cyclists have actually recorded a cardiac output of 40 litres per minute.

So, that means every little bit of blood is circulating around the body, so quickly that 40 litres worth of blood are circulating out of the heart every minute.

It's amazing, isn't it? Especially as we only have, I don't know, three or four litres of blood in the body.

Okay, Laura also wonders about this redistribution of blood.

How does that help our exercise response? Well, this links back to getting hot, sweaty, and red skin, doesn't it? So, when we exercise, blood is redistributed to the working muscles to ensure maximum flow where it's needed most.

So that involves that vasoconstriction squeezing up of arteries, or in fact it's the arterioles, the smaller branches of the arteries.

So, there's vasoconstriction to the digestive system, and there is vasodilation opening up of the arteries that feed the working muscles and also the ones that feed the skin.

Okay, let's do a quick check.

Which of the following happens when we start to exercise? Is it A, vasoconstriction reduces blood flow to the digestive system? Is it B, vasodilation decreases blood flow to the working muscles? Or is it C, vasodilation increases blood flow to the working muscles? What do you think? That's right, A and C are both correct, aren't they? Which brings us nicely into the second task of today's lesson.

So, I'd like you to do two things now.

I'd like you to describe the heart rate response to different types of exercise and why we get hot, sweaty, and red skin and then secondly, I'd like you to explain the combined benefit of these responses to the performer.

Pause the video now whilst you do that and come back to me when you're ready.

Well, let's see if what you came up with is similar to this.

So, we've got an increase in heart rate during exercise.

During lower intensity exercise your heart rate might plateau at about 120 to 160 beats per minute whereas during maximal exercise your heart rate can go up to a maximum of 220 minus your age.

For example, 204 beats per minute for a 16-year-old before fatigue will kick in.

And then lastly, blood is redistributed to where it is needed most by vasoconstriction of the arterioles supplying the digestive system to reduce blood flow there whilst vasodilation to the arteries or arterioles supplying the working muscles and the skin which increases blood flow there.

This combined with sweating helps prevent overheating.

And then the second part of this question was asking about the combined benefit to the performer.

Well, heart rate increases to provide more oxygen rich blood to the working muscles, and that provides the energy for movement.

It also helps remove carbon dioxide and fatiguing byproducts like lactic acid which would impair performance.

Meanwhile redirecting more blood to the working muscles, and less to the digestive system further increases that blood supply to our muscles during exercise.

As a consequence of that more oxygen, and more nutrients are made available to the performer, and therefore, they can keep exercising harder and for longer.

Finally, we sweat, and the skin goes red, and because of this more blood is also sent to help remove that excess heat produced within the body.

Okay, then let's jump into the third part of today's lesson where we look at the respiratory responses to exercise.

So, when we start to exercise there are a number of immediate changes that happen with the respiratory system.

Lucas is wondering can you name and describe any of these changes? Let's summarise them quickly.

So, we've got an increased frequency or breathing rate.

We've got an increased depth of breathing.

We get an increased tidal volume, and we also get an increased gaseous exchange happening.

Let's look at those in a bit more detail.

So, Laura is wondering what happens to your breathing frequency during exercise and why does that happen? I bet you know this one, don't you? That's right exercise triggers a need for more oxygen to be supplied to the muscles and more carbon dioxide to be removed.

Consequently, oxygen comes from the air that we breathe in, so we will need to increase our breathing frequency from about 16 to 20 breaths per minute at rest up to 40 to 60 breaths per minute during maximal endurance exercise.

You look at someone who's running hard or exercising hard they'll probably be breathing 40 to 60 times per minute.

Laura's got another question for us.

What happens to your depth of breathing, or your tidal volume during exercise, and why does that happen? Well, we also breathe deeper during exercise, don't we? You can feel that sense of more air being exchanged.

So, your tidal volume at rest is about 500 millilitres and it increases to enable a greater exchange of oxygen and carbon dioxide at the alveoli.

The pectorals and the sternocleidomastoid muscles also engage to help lift that rib cage up and out more.

This creates a bigger chest cavity so more air can rush into the lungs.

If we look at a little spirometer trace of that we can see how that tidal volume will increase into that inspiratory reserve volume, and also into the expiratory reserve volume, so that we've got a bigger volume of air being exchanged per breath, and we also breathe more frequency so the frequency of those waves will also increase.

So just a reminder that the tidal volume is able to increase during exercise because the inspiratory reserve volume and the expiratory reserve volumes decrease.

Okay, let's do a quick check.

Which of the following is incorrect? Is it A, tidal volume increases during exercise? Is it B, inspiratory reserve volume decreases during exercise? Is it C, expiratory reserve volume decreases during exercise? Or is it D, residual volume decreases during exercise? What do you think? That's right it's D.

So, your residual volume does not change at all.

That's the amount of air that's left in your lung always to stop them collapsing.

Okay, so Laura is wondering what is gaseous exchange, or gaseous exchange and what happens to it during exercise? Do you know? And here we've got a little illustration of the movement of these particles across the cell wall, and yeah gaseous exchange is the movement of gases that takes place at the alveoli and at the muscle site.

So, gases move from a place of high pressure to a place of low pressure or high concentration to lower concentration, so they're moving until they equalise.

So therefore, oxygen diffuses into the bloodstream at the lungs because there's less oxygen in the passing bloodstream, and then it's unloaded at the muscles because there is less oxygen at the muscle site, and then it's used for aerobic respiration.

Meanwhile carbon dioxide does the reverse, so it's produced at the muscles, so therefore it diffuses into the bloodstream gets carried by the blood back to the lungs, and then that high concentration of carbon dioxide diffuses out into the alveoli, so that we can breathe it out.

So, another quick check then.

True or false? Gaseous exchange is the movement of oxygen and carbon dioxide from areas of high concentration to areas of lower concentration.

That's right that's true, and can you tell me why? Well done.

So, gases move from high concentration or high pressure to areas of lower concentration or lower pressure until there's equilibrium i.

e.

, until they're the same.

So the body is only able to accept more oxygen if supplies in the bloodstream are depleted, or if you've got more haemoglobin that's capable of carrying it, and that's why people go and do altitude training to try and create more haemoglobin in their body so they can carry more oxygen.

More on that in a different lesson.

Okay, that brings us to our third task from today's lesson.

I'd like you to describe the three main respiratory responses to exercise and then I'd like you to explain how rates of gaseous exchange will adjust in response to a gentle walk, a jog, and then a maximal effort to exhaustion run.

So, for example you might have had to go at the multi-stage fitness, or bleep test where you go faster, and faster and faster until you can't carry on.

Pause the video now whilst you do that and come back to me when you're ready.

Okay, let's have a little look at what you came up with.

So breathing frequency increases by breathing more times per minute to get more air in and out of the lungs.

Tidal volume increases so that increased depth of breathing results in greater quantity of air inspired, or expired per breath, and then gaseous exchange happens faster during exercise as there's a bigger difference in the concentration or percentage, or pressure of oxygen in the alveoli compared to the bloodstream so it diffuses faster into the blood and then the same thing happens at the muscle site.

The oxygen diffuses into the muscle, and meanwhile more carbon dioxide that's been produced in the muscle diffuses out, and then exits the body via gaseous exchange.

What about this second question then? So, gaseous exchange happens a bit faster during a gentle walk compared to rest as the muscles will require a bit more oxygen, and will be producing a bit more carbon dioxide.

However, once intensity increases to a jog that increased aerobic respiration will require significantly more oxygen, and produce lots more carbon dioxide, so diffusion of both O2, and CO2, or oxygen, and carbon dioxide will happen faster as the concentration difference is greater, and then a maximal effort run, or sprint to exhaustion results in recruitment of additional skeletal muscles to enable the highest ventilation rates possible, and the biggest amount of gaseous exchange, but unfortunately lactic acid will build up, and that causes fatigue and eventually needing to stop exercising.

Okay, that brings us into the last bit of today's lesson where we're gonna look at those short-term effects of exercise i.

e.

, what happens in the next few days after a really hard training session or competition.

So, Laura's wondering what do you feel as soon as you finish exercising? I'm sure you felt tiredness or fatigue, lightheaded maybe, nausea even if you've worked really hard it can leave you feeling a little bit sick, and then aching, and that muscle aching is called delayed onset of muscle soreness or DOMS, and it's due to some micro tears in your muscles.

We'll come back to that in a moment, but it's quite different to crump which you might also have experienced which is to do with salt.

So, the effects of exercise can be felt for a few days, and I'm sure you've felt this before.

Strenuous exercise results in fatigue, tiredness in the muscles and the inability to perform at such high intensities for a bit.

So, if you've done a really hard training session or competition you definitely don't wanna try again the next day because you are feeling fatigued.

You need to give your body time to rest and recover.

You also might have felt low blood sugar or blood pooling in your legs, for example that leads to a reduced blood pressure and can cause that lightheadedness or dizziness.

If you've ever done perhaps a bike ride to exhaustion on a bike ergo, you're cycling hard, cycling hard, then you get to the point where you have to stop, you try and get off and you might be a little bit dizzy.

So, again that's because of that blood pooling that happens in your legs.

It's why a cool down is so important, and let's remember that overexertion, so if you really push your body to the limits, it can even cause nausea, so that sickness or vomiting.

Let's do a quick check.

Which of the following is unlikely to be felt immediately after exercise? Is it A.

Tiredness or fatigue, B.

Lightheadedness, C.

Nausea, or D.

Adrenaline.

That's right it's adrenaline.

That's something that we feel before or during exercise.

I'm wondering have you ever felt muscle pain the next day especially after perhaps a weight session? Well, muscle pain and stiffness the next day is caused by microscopic tears in your muscles, and these aren't a bad thing.

This is known as DOMS, or Delayed Onset of Muscle Soreness, and it's actually required because without DOMS your muscles can't grow back, or repair bigger and stronger, so you want a certain amount of DOMS, but not too bad to be I guess putting you off exercising again soon.

So, Laura's wondering what's the difference between DOMS and cramp? Well, in contrast to DOMS muscle cramps are painful involuntary muscle contraction either during or after intense exercise.

Cramp can be prevented by staying hydrated and taking on essential salts lost through sweating.

So, you wanna take on water but also some salt so that that water is taken into the bloodstream far better.

So, a quick check.

True or false? DOMS is the result of micro tears in the muscles and should be avoided wherever possible.

That's right that's false isn't it, and can you tell me why? Yeah, because Delayed Onset of Muscle Soreness or DOMS is the result of micro tears.

These are necessary for muscles to grow back bigger and stronger, and hence is a necessary evil or a necessary outcome of training.

So, let's have a little look at a summary then.

So, the immediate effects of exercise are what goes on in our body during exercise.

The short-term responses are how does your body feel in the 12 to 36 hours after exercise, and then in a later lesson we will also look at the long-term effects of exercise.

So, how does our body adapt and change in response to months of regular exercise? Okay, so the last task for today's lesson I'd like you to explain the difference between DOMS and Cramp.

Pause the video now whilst you do that and come back to me when you're ready.

Let's compare your answer to mine then.

So Delayed Onset of Muscle Soreness, or DOMS is the pain and stiffness felt in the muscles for up to 36 hours following exercise.

It's caused by microscopic muscle tears, and it's a perfectly normal result of training hard that is needed for muscles to hypertrophy.

In contrast cramp is a sudden and painful involuntary muscle contraction during or immediately after intensive exercise, and it should be avoided by staying well hydrated, so drinking plenty during an endurance event.

That leaves me just enough time to summarise today's lesson.

So the immediate effects of exercise happen as soon as we start exercising, and they include getting hot, sweaty, and red skin, increased heart rate, increased depth and frequency of breathing, and then we've got the short-term effects of exercise, and these are the things that happen in the 36 hours or so after exercise, and they include tiredness and fatigue, lightheadedness, nausea, DOMS and cramp.

Thanks very much for joining me for today's lesson, and I'll see you next time.