An experiment to find the effect of exercise on pulse rate

Prediction:

I am expecting my pulse, or heart rate, to increase as I do more exercise. Muscles need oxygen to work. The harder the muscles work, the more oxygen they require. Your heart and breathing rate increase so that more oxygen can be inhaled at an increased rate and pumped at this faster rate around your body, via your bloodstream. Extra carbon dioxide is produced by your muscles at this time, and this starts to build up in your bloodstream. The brain senses this is happening, and it sends nerve impulses to the heart making it beat faster, which is an automatic reflex. Due to this happening, more blood can then be sent to the muscles. The arteries attached to the muscles open up, whilst the arteries attached to other less needy organs get narrower. This way extra blood is diverted to the organs that need it most.

I am expecting my graph to look like this

As you can see, my heart rate increases at a steady pace, corresponding to the increase in exercise, so my graph has been drawn as a smooth curve.

ANALYSIS

In carrying out my experiment, I found that I had no anomalous results and I therefore did not need to repeat any measurements. I recorded my results on the table below:

Duration of exercise/ seconds

Beats per 30 seconds

Beats per minute (bpm)

Difference in heart rate to standing rate/bpm

to standing rate/bpm

0 = standing rate

36

72

0

30

74

48

76

60

87

74

02

90

97

94

22

20

02

204

32

50

03

206

34

80

03

206

34

Using these results, I have plotted a graph and drawn in the line of best fit. (See attached graph).

My graph shows that some of my prediction was correct, but some was not accurate. Whilst I had predicted that my heart rate would increase regularly and keep on increasing throughout the experiment, the graph actually shows although this happens initially, afterwards the rate of increase actually slows down as the exercise increases. Eventually the heart rate seems to reach a maximum rate and remains at 206 beats per minute, even though the exercise has increased. Your pulse does this because your heart can only beat a certain number of times per minute before it fails. Before this, you'd either get cramp, or be so out of breath, that you would not be able to continue exercising. If you were a trained athlete, you'd be specifically trained so that you could breathe in a way that would prevent this from happening.

EVALUATION

I think that my experiment was suitable and accurate enough for me to gain enough evidence to conclude that the more exercise you do, the higher the heart rate/pulse, until the heart reaches it's maximum rate. After this stage, it is constant. I drew up a table of results, then produced a graph. Using the points plotted on the graph, I managed to draw a smooth curve which is evidence that my results were reliable. There were no anomalies in my experiment, but there are ways of improving the experiment to make the results more reliable. You could use a machine to monitor heart rate, instead of feeling for it yourself, as you may miss out a few beats or add a few on accidentally. You could also use a treadmill instead of skipping as your exercise, so that you get even amounts of exercise.

If I could conduct my experiment again, I would do it all in one day, to make sure that my starting pulse is always the same, which would make my results more reliable and accurate. Also, to extend the experiment, I could measure how long it took for my heart rate to get back to its normal standing rate, which would be an indication of how efficient my muscles were.