Lesson video

Hi there, welcome to your lesson.

My name's Ms. Hacking, and I'm really looking forward to our lesson today.

Today's lesson is on the types of muscle and muscle fibre.

By the end of today's lesson, I'm hoping that we can all identify the different types of muscles and different types of muscle fibre, and explain their function.

Our keywords include voluntary, involuntary, cardiac muscle, slow twitch, and fast twitch.

You may want to pause this slide now to make a note of the definitions of these keywords that can help us in today's lesson.

Today's lesson is going to be split into two learning cycles.

In the first learning cycle, we're gonna be describing the different types of muscle.

And in the second learning cycle, we want to explain how different muscle fibres are used.

Let's get started.

Muscles are involved in every movement of the human body, whether it's from waving our hands, nodding our head, blinking our eyes, or doing a more sport-specific action.

There are three different types of muscle, categorised depending on their location and function as follows.

Voluntary muscle, involuntary muscle, and cardiac muscle.

What do you think is a difference between these types of muscles? Voluntary muscles.

These are attached by tendons to bones and enable movement to cross a joint.

The main thing we need to remember is that they are under our conscious control and contract to initiate movement when we want them to.

For example, if I'm choosing to wave my hand, my muscles are contracting to allow that movement.

Equally, if I want to do a bicep curl, I am consciously in control of doing that movement and contracting those muscles.

So, the bicep and triceps are examples of voluntary muscles.

I wonder if you can think of any other examples.

Involuntary muscles.

These are found in our internal organs.

They contract in waves to help with the flow of products inside them.

We do not have conscious control, and they work automatically.

For example, the muscles near my large intestine, I can't suddenly stop working.

I can't choose to stop them working.

These muscles are not under our conscious control.

I can't suddenly stop these muscles working.

They just automatically work without thinking.

So, you can find them in the walls of your digestive system, in blood vessels, in the bronchi, in the uterus, and in the bladder.

The cardiac muscle.

You may have already known this one.

The cardiac muscle is a type of involuntary muscle found in the walls of the heart.

Again, it's involuntary, because I'm not thinking.

I'm not making my heart contract.

It is automatically doing that, and it needs to do that in order to get the blood going around the body.

It contracts without our conscious control and it works nonstop without ever tiring.

If the heart stops, we will die.

So, it's important that it keeps pumping and keeps working automatically without us having to think about it.

When a cardiac muscle contracts, it pumps blood out of the heart and around the rest of the body, which is how we get oxygen and other products around our body.

Let's have a go at a question.

Which of the following is directly involved in helping us to move around and play sport? Is it, A, voluntary muscles? B, involuntary muscles? Or C, cardiac muscle? That's right, it's voluntary muscles.

Muscles like the bicep and tricep, muscles like the hamstring and quadricep, for when we're running, they're voluntary muscles that help us move around in sport.

Okay, let's have a go at another check.

Which of the following is essential in maintaining healthy body systems and digesting food? Is it, A, voluntary muscles? B, involuntary muscle? Or C, cardiac muscle? That's right, it's involuntary muscles.

Remember, involuntary muscles work without us consciously thinking about it.

We don't consciously think about our digestive system digesting the food that we've just eaten.

We don't tell our muscles to work to do that, therefore they're involuntary muscles.

Okay, now it's time for you to have a practise by yourself.

Task A, first part, I would like you to complete the table to describe the types of muscle in the body.

In this table, you need to have the type of muscle, the function of that type of muscle, and then an example of where that could be found in the body.

For the second part of this task, I'd like you to provide examples of how all three are required by a marathon runner.

You may wish to pause the video now in order to write your answers.

Good luck.

Okay, question one, complete the table to describe the types of muscles in the body.

You may have started with the voluntary muscles.

So, the type of muscle would've been voluntary.

The function is attached bone to muscle.

They're under our conscious control and their job is to help us move.

So, these are the voluntary muscles that help us move, help our body move, particularly for sport.

And an example could be the quadriceps, but you may have said a number of other examples as well.

Another type of muscle is an involuntary muscle.

And the function of the involuntary muscles are that they're found in the internal organs and they contract automatically without us having to think about it.

You may have said that they're using the internal organs to help the function of the body.

So, the example that you could have said would be the muscular walls of the digestive system.

The muscles there help the digestion process take place.

And finally, a type of muscle could have been a cardiac muscle.

And this type of involuntary muscle is only found in the walls of the heart, and is responsible for pumping blood around the body.

And the only example you could have had there was the heart.

So, well done if you got that correct.

So, for the second part of this task, you were asked to provide examples of how all three are required by a marathon runner.

You may have written something along these lines.

A marathon runner needs voluntary muscles in their legs to contract repeatedly to enable them to move.

This answer could be made better by giving those examples of muscles in the legs.

So, for example, the quadriceps and the hamstrings.

A cardiac muscle is required to pump blood containing oxygen around the body to provide energy for exercise.

Again, we need to say how the heart, the cardiac muscle, is there to pump blood, to transport oxygen around the body, as it's needed in the working muscles when we exercise.

And finally, involuntary muscles in the blood vessel walls squeeze to help push blood to the working muscles and back to the heart.

You may also mention that digestion also continues during a marathon race to get energy from food and drink to fuel the long race.

Again, we could argue that, if these muscles were not working properly, that our body would not function properly, and therefore would not be able to run the marathon as well as they could if it was functioning.

Well done if you talked about all of those different things.

Okay, let's move on to the second part of today's lesson.

We want to explain how different muscle fibres are used.

Let's go.

So, within every muscle, there are thousands of individual muscle fibres, a bit like a pack of spaghetti.

They all run along over each other, a bit like train tracks.

There are two types of muscle fibres.

They are slow twitch, type one.

Or fast twitch, type two.

Our individual makeup of these different muscle fibre types is influenced by our genetics, by training, and by the muscle location.

So, where they are in the body.

Let's have a look at the different types of muscle fibres.

So, a slow twitch, which is a type one.

They have good oxygen supply.

They can work for long periods of time at low intensity.

I wonder if you can think about which physical activity or sport these muscle fibres might be more suited for.

Fast twitch, or type two muscle fibres, are the opposite.

They have a less oxygen supply.

They work quickly with high bursts of energy and they work for a short period of time.

So, again, can you be thinking about which type of activities might be better suited to the fast twitch muscle fibre? Type one muscle fibres, also known as slow twitch fibres, have an excellent oxygen supply via capillaries.

They have lots of myoglobin and mitochondria which are responsible for aerobic respiration in the muscle.

Aerobic, that's going to be a crucial word that we need to know.

Aerobic involves oxygen.

And when we see the word, aerobic, we often think for longer periods of time.

So, again, we are thinking about which type of activities the slow twitch muscle fibres might be more suited for.

So, slow twitch muscle fibres can work for long periods of time.

However, they are only able to contract at fairly low intensity, so are no use in situations that require speed or power.

So, by now, I'm hoping that you've thought about the type of activities that slow twitch muscle fibres would be more suited for.

An example would be a marathon runner.

They move for a long period of time, but they would move at fairly moderate to low intensity, as you would not be able to keep fast, high, hard intensity up for the length of time it takes to run a marathon.

Any endurance events would be more suited for slow twitch muscle fibres.

Okay, let's have a go at a check.

Which of the following activities relies predominantly on slow twitch muscle fibres? Is it, A, a rugby scrum? Is it, B, a hundred metre sprint? Or is it, C, an Olympic distance triathlon? It's C, an Olympic distance triathlon, as this would take a lot longer to do than to play in a rugby scrum or to run a hundred metre sprint.

This would be using our aerobic respiratory system, and therefore, we would want to work at a lower intensity for a longer period of time, which is why slow twitch muscle fibres would be perfect for this event.

Type IIa have characteristics of both slow and fast twitch muscle fibres.

They use oxygen to work aerobically, just like slow twitch muscle fibres, but they also contract with more force, therefore are more like fast twitch muscle fibres.

They have characteristics of both slow and fast twitch muscle fibres.

Type IIa fibres are also highly responsive to training, so we can adapt to be better suited to either endurance or power events, but not both at the same time.

So, for example, a 200 metre sprint relies on Type IIa muscle fibres.

Slightly different, Type IIx muscle fibres fatigue quickly and they do not have any aerobic capabilities.

So, they work really hard, really intensely for a very short period of time, but they cannot work hard for any longer, because they get tired really quickly.

So, they contract with maximal force and at a high speed for most explosive activities.

These muscle fibres need rest before they can contract again.

An example of this would be weight lifting.

So, lifting an incredibly heavy weight, they would be able to contract once, do the lift, but then they would need to rest before, then, completing any other type of lifting or exercise again.

So, to summarise, slow twitch muscle fibres are type one muscle fibres.

And marathon runners are examples of people that may have and may need slow twitch muscle fibres.

Fast twitch muscle fibres can be split into two.

Type IIa and these are the mixture of slow and fast twitch muscle fibres.

And an example of a sport that might need these would be the 200 metre sprinter.

But also fast twitch muscle fibres include Type IIx.

And for example, these are the ones that are explosive and really high intensity, but they fatigue quicker.

So, a weightlifter would be an example of that.

Let's have a go at to check to see how much you can remember.

Which of the following activities relies predominantly on Type IIx fast twitch fibres? Is it, A, a rugby scrum? Is it, B, a 400 metre running race? Or is it, C, an Olympic distance triathlon? That's right, it's a rugby scrum.

Muscle fibres would need to work really explosively to make the scrum to push, and then they would fatigue quickly.

They wouldn't be able to keep in that scrum position pushing for a long period of time.

Okay, now it's your turn to have a go at a practise task.

Can you explain which type of muscle fibre the following activities rely on the most? A, a somersault in the high diving competition.

B, a 50 metre butterfly swimming race.

C, a 2000 metre row taking eight minutes to complete.

D, a Tour de France cyclist.

E, a slam dunk in basketball.

And F, a marathon runner.

You may wish to pause this slide, so you're able to complete this task with enough time.

Okay.

So, the task was to explain which type of muscle fibre the following activities rely on the most.

A, a somersault in the high diving competition.

You may have written fast twitch Type IIx due to explosive power required to propel whole body weight into the air and rotate quickly.

B, a 50 metre butterfly swimming race.

You may have written fast twitch Type IIa due to high force of contraction, but needing to keep contracting for about 30 seconds, it still needs some oxygen present.

So, if we remember, the Type IIa involved a mixture of the fast twitch and the slow twitch muscle fibres where oxygen was involved, but we do still need explosive power.

Well done if you got that correct.

C, a 500 metre rowing race.

This would involve fast twitch Type IIa due to relatively high force of contraction, but for a prolonged period.

D, a Tour de France cyclist.

That would involve slow twitch type one due to the long duration of the event.

But during sprint finishes or very steep hill climbs, fast twitch fibres will be used, which does show that some sports require both fast and slow twitch fibres at different points of the match or at different points of the event.

E, a slam dunk in basketball.

This would require fast twitch Type IIx due to explosive power required to jump into the air to score the slam dunk.

F, a marathon runner.

This would involve slow twitch type one due to the low force of contraction and need to work aerobically to last the whole race.

Now, that just leaves us enough time to summarise today's lesson.

We have three different types of muscles in the human body.

Voluntary muscles.

As sports performers, we rely on these skeletal muscles to enable us to move.

They're under our conscious control and contract when we want them to.

Involuntary muscles.

These are found in the walls of internal organs, like the digestive system and blood vessels.

They help squeeze food and blood along.

They work without the need for conscious thought.

And cardiac muscle.

The special type of involuntary muscle only found in the walls of the heart to pump blood.

Skeletal muscles have two types of muscle fibre, fast twitch, which work anaerobically, and slow twitch, which work aerobically.

It's been great to be your teacher today.

Well done for all your hard work on your learning.

I look forward to seeing you again soon.