Hi, there! I'm Mrs. Cam and welcome to today's lesson all about the effect of exercise on our pulse rate.

This is part of the "Health and disease" unit.

So let's get started then.

Our main outcome for today is I can describe how to measure a person's pulse rate before and after exercise and also calculate their recovery time.

We'll be using lots of key terms today.

Here are some of them.

If you would like to pause a video and have a read of those properly, please do.

But rest assured that I will go through each one of these as we move through the learning cycles.

We actually have three learning cycles today then, investigating recovery time, collecting data, and also calculating recovery time.

We will be starting with investigating recovery time.

So have a little think about this when you've done some really vigorous exercise.

So let's say like running or playing a sport, actually what happens to your body? How do you feel? Did you think about the fact that you might feel quite hot? So your body temperature will increase, you may become quite breathless and you may be breathing a lot faster, that's called your breathing rate.

And also your pulse rate is increasing and we're gonna talk about that in a little bit more detail.

But essentially, all of these physiological responses.

So all of these responses that our body is having are actually linked to cellular respiration.

So when we exercise, actually what's happening is our muscles are contracting, so they're getting shorter.

We can see in that image of an arm there and we can see where the muscle is attached to bone via a tendon.

As that muscle contracts, then, it needs energy from cellular respiration in order to do so.

So cellular respiration is that process that actually uses glucose and oxygen as a fuel in order to provide energy.

And that energy in the case of exercise is going to be needed to contract that muscle.

Now, in order to get oxygen and glucose, they're needed to be pumped by our heart in the blood around our body.

All right, so that is how it reaches all of those cells in order to carry out respiration.

Is the heart then that pumps that blood around the body and it will need to go through all of those different blood vessels in your body.

And when we exercise because there is an increased demand for oxygen and glucose in order to carry out cellular respiration, then actually the heart's gonna need to beat faster.

When it beats faster then, that will increase your pulse rate.

That feeling of the blood moving through the arteries.

It will also need to increase because as well as taking oxygen and glucose to those respiring tissues, it also needs to remove carbon dioxide as a waste product of respiration, so that then it can be taken to our lungs and we can breathe it out.

So your heart rate or your pulse rate is actually the number of times your he beats in one minute.

And it's usually recorded in beats per minute or we call that BPM.

We're all going to have a go at actually measuring our pulse rate.

Okay, so if you find your left arm, okay, and we'll watch this video first of all in order to work out how we actually take our pulse rate.

Okay, so we took our left hand, we took our four fingers and we placed those onto our wrist and felt how many beats there were in 30 seconds and multiplied that by 2.

So to measure your pulse rate, place your thumb on your wrist of your other hand and count the beats.

Is that true or is that false? Can you justify your answer? You place one finger on the thumb of the other hand or you place your first two fingers on one hand on the thumb side of the wrist of the other hand.

I'll give you a moment to think about it, but if you need more time, please pause the video.

That was, of course, false because actually we want to take the first two fingers and place those on your other hand onto your wrist.

Excellent, well done.

Okay, so when we've done exercise, actually the time it takes in order for our pulse rate to return back to its normal resting rate is known as recovery time.

And if you have a really good healthy heart and good cardiovascular system, then actually your recovery time is going to be shorter, okay? The more you exercise and the fitter you are, the more it will build and strengthen your heart muscle.

And that is why your recovery time is then shorter.

We're going to have an investigation then to look at recovery time.

And the way that we're going to do that is we're going to look at a person's pulse rate after exercise.

The level of exercise remember will have an effect on the pulse rate because we are in an increased demand for oxygen and glucose to carry out respiration.

And then also, we'll need to be removing more carbon dioxide from those respiring tissues.

Vigorous exercise, such as running, would increase your pulse rate more than just say walking around.

Just standing up will change your pulse rate from a resting pulse rate from sitting down.

But then as soon as we start to up our level of activity, it's going to increase your pulse rate more and more.

And of course, that would then lead to a change in your recovery time.

Somebody walking, they would recover much faster when they sit down comparatively to someone who has gone for a run.

(clears throat) Okay, so in our investigation then our independent variable is the time after exercise in minutes.

Our dependent variable is our pulse rate.

Our control variables are the type and duration of exercise doing 60 jumping jacks in minute.

And also, we're going to use something called a metronome, which basically hits a beat every time you set it and that will help us to do exactly 60 jumping jacks in one minute.

So in order for us to do this investigation, we'll need to draw a table.

Remember the rules for drawing a table, we should have the independent variable there in the first column and then our dependent variable in the second column, underneath our title for what is in each of those columns.

We should make sure that we put our units and we can put those units into some brackets.

Okay, I'd like you to draw a table to record the results for the investigation into the effect of exercise on recovery time.

I'll give you a moment to think about it, but if you need more time, please pause the video.

Okay, so our independent variable then is our time after exercise and that's gonna go into our left-hand column and our pulse rate in BPM is going to be in our right-hand column.

Of course, our time after exercise is going to be every minute.

All right, then, so onto our first task of the day, please get your worksheet out and open that up to record your results.

Number one, describe how you can find a person's pulse rate.

Number two, describe a method to control the type and duration of exercise undertaken by a test subject.

Can you think of more than one way? I'll give you a moment to think about it, but if you need more time, please pause the video.

Okay, so our method for finding the pulse rate is to measure your pulse by placing the first two fingers of one hand on the thumb side of the wrist of the other hand, and count the number of beats you feel in 30 seconds.

You can then multiply that by 2 and record in your data table.

Number two, then a method for controlling the type and duration of exercise.

The example that I gave then is that the test subject to do 60 jumping jacks in one minute and using a metronome to make sure that we keep pace.

But any other sensible suggestion, such as stepping up and down on some stairs for a certain amount of time, things like that, as long as you've controlled the number and the pace.

Okay, onto our second learning cycle then, which is collecting data.

So our method for measuring pulse rate, resting pulse rate then that is when we've been sat down and we need to be sat down for a certain number of minutes.

We are going to go for two minutes.

Then we take our pulse, we take that remember over 30 seconds because then we are less likely to lose count, and then we multiply that by 2 and we can record that onto our worksheet.

That will give us beats per minute.

Sometimes when you first take your resting pulse rate, it can go up a little bit because you're a bit nervous or thinking too hard about counting.

And so it's always important to make sure we repeat this three times, so that we get an average result.

We can then calculate the mean or average of these three measurements.

So let's have a go at doing that then.

Izzy counts 38 pulses in 30 seconds.

What is the pulse rate in beats per minute? We would first of all need to multiply that by 2, okay? 'Cause remember we've only counted in 30 seconds and so 38 times by 2 gives us 76 beats per minute.

Now, she actually found three values of 76, 79 and 73.

To find an average, we need to add them all up and divide by the number of readings that we took.

So we add up those and we divide by 3, which is the number of readings that was taken.

And that gives us an average of 76 beats per minute.

I'd like you to have a go at those then for yourself, for Jacob.

So Jacob counts 42 pulses in 30 seconds.

What is the pulse rate in beats per minute? Jacob finds three values of 84, 85, and 83.

Find the mean value.

I'll give you a moment to think about it, but if you need more time, please pause a video.

Okay, so to calculate the beats per minute, we multiply that by 2.

So it's 42 times by 2 gave us 84 beats per minute.

To find the average, we need to add them all up together, divide by the number of values that there are, which is 3, and that gives us 84 beats per minute.

I hope you've got all those right.

Really well done.

Okay, so then we're going to run through the method of how to collect data on fitness.

We can actually find this in on our worksheet, okay? So there is a table for us to record our results.

So measure your resting pulse rate and record it in the table.

Then we're going to do 60 jumping jacks in one minute and sit down immediately.

Measure the pulse rate for 30 seconds and multiply that by 2 so we get beats per minute.

Record this in the table in the row for 0 minutes.

Repeat step 3 at 1, 2, 3, 4, and 5 minutes after the exercise, and record in the appropriate row in the table.

So this is task B then.

So if you could get your worksheets out to record everything on there, I'd like you to first of all take your resting pulse rate three times, calculate your mean, then carry out the investigation and complete a results table.

I'll give you a moment to carry that out, but you will need more time, so please do pause the video.

Okay, for my sample data then that you can use later if need be.

Then I got resting pulse rate of 63 beats per minute.

At 0, I got 140.

1, 125.

2, 100.

3, 93.

4, 82.

And then we can see by 5, five minutes the resting pulse rate had returned to normal.

You may have very different values to this, so please don't worry.

But this is just a sample of what your data might look like.

Okay, onto the final learning cycle then, calculating recovery time.

So when we calculate recovery time, we're going to need to draw a graph.

Scientists often display their data as a graph 'cause it allows us to see correlation, so the trend and pattern in the data.

Which type of graph do you think we should we use a bar chart or a line graph? Now, bar charts we use when the data is categoric.

So we can see here that we've got categories of people, okay, that are in a class, but it could be hair colour.

So blonde and brown, they're not numbers, they are categories.

Whereas a line graph is always used when the data is continuous, which is most of the time that means that they are numerical.

The data for recovery time is continuous, therefore, we are going to need to draw a line graph.

To draw a line graph, we will need a ruler, a sharp pencil, and a piece of graph paper.

So you will all need these things in order for this learning cycle.

And when we draw our graph then, the independent variable always goes on the x-axis and the dependent variable always goes on the y.

So this is our quick check about that then, we should use a bar chart for plotting recovery time.

True or false? Can you justify your answer? Recovery time is categoric data.

Or b, recovery time is continuous data.

I'll give you a moment to think about it, but if you need more time, please pause the video.

Okay, did you realise that that was false? And that is, of course, recovery time is continuous data and therefore, we will need to plot a line graph.

Excellent, well done.

So we're going to have a go at plotting this data onto this graph, okay? And for demonstration purposes, we've only got three points to plot.

However, on a line graph, you really need at least five data points in order to plot onto a line graph and that's because then we can be more sure that there is actually a pattern there.

On our x-axis then, we have our independent variable.

Our independent variable for this one was the time after exercise and we've also got our units in there, which was every minute.

On the y-axis then we've got pulse rate or which we measured in BPM.

When we put in our numbers onto our x and y-axis, we need to make sure that the increments, so the space between each point is evenly spaced, okay? So we need to make sure that we're going up by 1, 2, 3, 4, 5.

And then you can see that I've used 20 little squares every time I've increased by one minute.

We can work out what each of those little squares is worth by essentially dividing the number that we have increased it by.

So looking at pulse rate, we've gone up to 100 look by using 20 little squares.

So we divide 100 by the number of little squares, which is 20.

So that tells us that every little square is worth 5 on the y-axis that will be different on the x-axis because 20 little squares are being used for just one minute.

So we need to go up by 162.

Okay, along at 0 for our first point.

Our next point at one minute, we need to go up to 100 and you can see that I'm using little crosses to in order to indicate where that point is.

And finally, on the second one, it's 95.

So I go up at 2 to 95 and again, I draw a little cross.

You can use your ruler to help line it up as you are putting in your points.

I'm then going to draw a line of best fit.

This is best to be a nice smooth curve for this one.

However, if you are struggling to find where that line of best fit is.

In biology, it's probably better to join the points up with a ruler if you're not sure where that line is.

But I can see that there's a nice smooth curve there, so I put that in.

We're then going to find the resting pulse rate, okay? And draw that along the as a horizontal line from the point at the y-axis as my resting pulse rate.

So there we go.

I'll pop that in there.

And I'm doing it as a little dashed line look, so that you can see that that's different from my smooth curve.

The resting pulse rate is the time it takes for the pulse rate to go back to that normal resting point after stress.

So in this case, the stress is exercise.

So if I have a look, it goes back to normal by the time it gets to that point where the arrow marks.

And then if I look down onto my x-axis, the recovery time for this individual was just two minutes.

Okay, can you match up the variable to the axis? I've got the dependent and independent variables and I've got the x and y.

I'll give you a moment to think about it, but if you need more time, please pause the video.

Okay, I've matched dependent up with the y and the independent variable with the x-axis.

Excellent, well done.

Okay, so onto task c then if you get your worksheets out, there should be some graph paper there for you to draw this on.

And I would like you to draw a line graph for your results.

If you haven't got any results 'cause you weren't able to carry out the practical, please do use the sample data and then we can use our graph to calculate recovery time and answer this quick question of how can you shorten your recovery time? So I'll give you a moment to think about it, but to draw a graph, you are going to need more time, so please do pause the video.

Okay, here's some sample data then if you weren't able to collect your own, and I'll show you what my graph looks like with that data in a moment.

But your graph should have the independent variable on the x-axis, labelled with units, for example, time after exercise in minutes.

The dependent variable should be on the y-axis, labelled with the units, example, pulse rate in beats per minute.

Each one of your increments on both of the axes should be evenly spaced.

Correctly plotted data points, if you are working with another person, ask them to check your data points because it's actually quite difficult to check your own to make sure that you haven't made a mistake.

So if you've got someone else working with you, it'd be great for them to check.

Have you put in a smooth line of best fit, or maybe your results were all over the place and you needed to join them up with a ruler instead? Resting pulse rate shown using a dashed horizontal line.

So here is my graph.

Okay, these have been joined up point to point, instead of a smooth curve, so that you could see the difference.

I've got my resting pulse rate there as a horizontal line and actually it took five minutes, you can see it doesn't meet that resting pulse rate until five minutes.

So, therefore, that is the recovery time for this individual.

How could you shorten your recovery time? Exercising regularly.

Remember that will strengthen and build the muscle that we find in the heart.

Excellent.

Well done.

So we have very nearly finished.

I just want to go through the key learning points for today.

So measure your pulse rate by placing the first two fingers of one hand on the thumb side of the wrist of the other hand and count the beats.

Resting pulse rate is your pulse rate when at rest.

You should take your pulse rate three times and then calculate a mean.

You can control the level of activity taken by a test subject by doing a certain amount of exercise in a period of time.

For example, 60 jumping jacks in one minute.

Recovery time is the time it takes for the subject's pulse rate to return to the resting pulse rate.

I hope you've enjoyed today's lesson.

I've really enjoyed teaching you and I hope to see you again soon.

Thank you very much.

Bye now!.