Investigating the effect of exercise on the heart rate and recovery time.
There are different factors that affect the heart rate, they are the variables….
I have decided to go for distance run for our variable. I decided that the variables such as fitness and individual involved would be too hard to measure fairly.
As I decided to use distance run as my variable and I am going to use Mark as my ‘Guinea Pig’, so I am going to make Mark run 20 meters, 40 meters, 60 meters, 80 meters and 100 meters. I am going to change the distance run 5 times. I am going to record his resting heart rate, his heart rate straight after exercise and time how long it takes for him to recover. To make sure that my results are reliable and correct. I am going to take the average of these two sets of results and use the average for my graph and my final result.
For this experiment I am going to use…
- A heart rate monitor, to measure Marks heart rate – this consists of a belt and a transmitter belt. The belt is moistened so it can read the heart rate easier, then it is placed around the chest. The watch is fastened to the wrist where it picks up the heart rate from the belt. You must make sure that you don’t stand too close to someone else using the belt because you may pick up their signal.
- A tape measure, to work out how far he has to run. We will be measuring in metres.
- A stop clock, to time how long it takes his heart rate to return to normal, we will measure the time in minutes and seconds.
To make this a fair test I am going to only use one variable and control all of the other variables, like the person doing the exercise and the type of exercise and I am going to ask him to run at his normal pace instead of jogging or sprinting. I am going to make sure I use the same person each time because people come I all sorts of shapes and sizes, so some people can run faster than others and some people are fitter than others. Also I am going to make sure the person tries to stay the same speed because sprinting needs more energy than say, jogging so the heart rate will go up when some on is sprinting. I am going to keep the type of exercise the same as well because on type of exercise may need more energy than another so the heart rate will be different.
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I predict that further Mark runs the higher his heart rate will get and the longer it will take for his heart rate to return to normal. Because the further Mark runs the more oxygen his muscles need. This is because when he is working hard his body needs more energy to keep going. His body gets this energy from glucose and oxygen. The word equation for this reaction is…
GLUCOSE + OXYGEN CARBON + WATER + ENERGY
When he is resting he still needs to use his energy and use this reaction but at a normal, lower rate. You do still need energy when you are resting because of your involuntary muscles, such as the ones in your stomach and you use muscles and energy to keep your posture the same. So when he is working harder his body needs more energy quicker, so his heart rate goes up because the oxygen, which comes from the lungs and glucose, which comes from the intestines need to get to the muscles so it travels in the blood. And when Mark works harder the heart pumps the blood round the body quicker to get more oxygen and glucose to the muscles.
The web site ‘’www.smm.org/heart/lesons/lesson1.htm’’ says that ‘’ with exercise or physical activity, the heart rate increases to supply the muscles with more oxygen to produce extra energy. The heart can beat up to 200 times per minute with extreme exercise. The brain sends nerve signals to the heart to control the rate. The body also produces chemical hormones, such as adrenaline, which can change the heart rate. When we are excited, scared, or anxious our heart gets a signal to beat faster. During a fever, the heart beats faster to bring more blood to the surface of the body to release heat and cool the body. The heart rate increases during and after a meal to send more blood to the digestive system. A trained athlete's heart can pump more blood with each beat so his or her heart rate is slower. Likewise, an athlete's recovery time is shorter.’’
But when Mark has stopped working his heart rate will still be high because he will need to pay back the oxygen debt. This is because at some points when he is exercising he will respire without oxygen; this is called anaerobic respiration, because he may not take in enough oxygen for aerobic respiration. So when Mark has stopped working he has to ‘’pay back’’ his oxygen debt in order to break down the lactic acid, which is the incomplete break down of glucose. Lactic acid causes cramp in the muscles. The word equation for this reaction is…
GLUCOSE ENERGY + LACTIC ACID
The further he runs the longer it will take for his heart rate to return to normal because he would have had to work for longer so his oxygen debt would be greater.
Experiment 1, resting heart rate; 69
Experiment 2,resting heart rate; 85
Average of both experiments, resting heart rate; 77
From the graphs I can see that the longer the distance run the higher Marks heart rate was and the recovery time was longer. From the heart rate and distance graph I can see that the line of best fit runs up diagonally in a steady slope. There is one odd result which, I have circled this result may have been recorded wrong or may have just been a fluke.
From the graph on recovery time and distance I can see that the further Mark ran the longer the recovery time was. The line of best fit runs up smoothly and evenly then slopes up more vertically.
From my results I can see that the effect of exercise on the heart rate and recovery time is that as you do more exercise your heart rate gets higher and you recovery time is greater. This is because when you do exercise your body needs more oxygen and the more exercise you do the more oxygen you need. This is because the harder you work the body needs more energy to keep going. Your body gets this energy from glucose and oxygen.
When you are resting you still need to use your energy but at a normal lower rate. You need energy all the time even when resting because of your involuntary muscles so when you work harder your body needs more energy quicker, so your heart rate goes up because the oxygen, which comes from the lungs and glucose which comes from the intestines need to get to the muscles so it travels in the blood. And when you work harder the heart pumps the blood round the body quicker to get more oxygen and glucose to the muscles.
But when you stop working your heart rate will still be high because you need to pay back the oxygen debt. This is because at some points when you are exercising you will respire without oxygen; this is called anaerobic respiration, because you may not take in enough oxygen for aerobic respiration. So when you stop working you have to ‘’pay back’’ this oxygen debt in order to break down the lactic acid, which is the incomplete break down of glucose. Lactic acid causes cramp in the muscles. The word equation for this reaction is…
GLUCOSE ENERGY + LACTIC ACID
The further you run the longer it will take for your heart rate to return to normal because you will have had to work for longer so your oxygen debt would be greater.
I used mark as my ‘guinea pig’ and I made him run different distances 20, 40, 60, 80 and 100 meters) changing the distance 5 times. I recorded his heart rate straight after exercise and resting heart rate, so I knew when his heart rate had returned to normal, and how long it took him to recovery took the average of 2 sets of results. To make sure my results were accurate I used a heart rate monitor instead of finding out the heart rate manually. I used a stopwatch to record the recovery time and a tape measure to record the distance.
On each graph there was one odd result this may have been a wrong recording or a fluke. I think that the experiment was a success and the results were reliable but to improve the final results we could take a few more results and get a more accurate average result. I think the results that I collected are sufficient to support a firm conclusion. To extend the enquiry I could experiment how different types of exercise effects the heart rate.
Here's what a teacher thought of this essay
This investigation into the effect of changing the running distance on heart rate and recovery time is a competent piece of GCSE work which reflects a good understanding of basic exercise physiology. The writer presents a clear account of the theory, method and results. It could certainly have been improved in the following ways:  Use of standard scientific terminology when discussing variables (independent, dependent, controlled);  A more detailed discussion of controlled variables including some indication of how the subject would rest between trials;  A more detailed analysis of the data with references to specific results to support the conclusions made. Overall, 3 stars.