The aim of this experiment is to find out how different intensities of exercise effect the heart rate I will measure it in beats per minute using a polar heart rate monitor. Hypothesis: I predict that as I increase the intensity of the exercise I do, that my heart rate will increase. This is because as I exercise more intensely I will need more blood to my muscles to supply oxygen and take away carbon dioxide; therefore my heart is going to have to beat faster to keep up with oxygen demand, so oxygen debt doesn’t occur and so that carbon dioxide can be taken away as it is a waste product.
Variable to manipulate: For this I can use one of three choices these are;-1. Work rate, as in the speed I will go on the running machine and change for different intensities. -2. Time of work, meaning how long I will work for, and change for different time intensities. -3. The work load I will run with. I could change this for different intensities. I will use the work rate as my variable to manipulate; therefore I will be changing the speed at which I run in Km/h.
This means that I will not change the time I work for or the work load I work with. Variables to remain constant: I will keep through out my experiment four constant variables, these are the following; the heat, I will keep the heat at the same temp through my temperature in the room of which I exercise by making sure the air conditioning is set at a set rate of temperature. The time, I will keep the time I work for on the running machine the same at two minutes for each run.
I will use the same equipment throughout the experiment, this means that my experiment will be a fair test throughout; I will use the same clothes, shoes and running machine throughout the experiment. I will always make sure that before I start my exercise, that my heart rate is at its normal rate, therefore it would be a fair test as my heart rate wouldn’t start higher than normal therefore giving a higher result. I will also throughout the experiment be standing, because then my blood will go to the same parts of the body with the same amount of beats per minute.
Dependent variable: My dependent variable is my heart rate, I will measure straight after two minutes of exercise with my polar heart rate monitor that I will link up to the running machine. Values and Ranges: I will do five different intensities on the running machine, therefore meaning that I will do five different speeds (in Km/h) on the running machine. I will do each different intensity on the running machine three times, so I get a good range on my heart rate so I can figure out a reasonable average. I will measure my heart rate in beats per minute bpm.
My ranges in speed (work Rate) will be 5 Km/h, 7 Km/h, 9 Km/h, 11Km/h and 13 Km/h. I will do each speed three times to get a good range of results, of which I can work a reasonable average from. I will also measure my resting heart rate at the beginning of each experiment, and it can be three below or above the resting rate I will measure at the beginning of the whole experiment. Then when all data is gathered I will figure out the average of each three on different intensities, I will round the average up or down according to the figure.
Safety: During the experiment I will take the following safety measures to ensure I don’t get injured; – I am asthmatic, so I will make sure that I have my ventoline inhaler on me all the time. – I will make sure that the surface of the running machine is not wet incase I trip over and hurt myself. – I will make sure that my shoe lasses are tied up properly to insure that I don’t trip up. – I will also make sure that I have no incredibly loose clothing, so it doesn’t get caught in the machine and will take off any jewelry.
Preliminary Work: For this I went down to the school gym and I tested four pieces of machinery. I decided to use the running machine as I would be worked at a set rate therefore it would be a fair test. I also used the step machine, the cycling machine and the rowing machine I figured that these wouldn’t be a fair test as I could relax slightly when I tired so I decided against them. The reason I went for the running machine is that I would be on a conveyer belt that is moving at a fixed rate and therefore I can’t relax if I tired.
Method: I will use the same running machine, which is placed in the gym. Before I get on the running machine I will link a polar heart rate monitor to myself, I will do this by wetting the strap, wetting the strap allows good conduction, therefore it will pick up the electrical charges from my heart more accurately, which I will strap round my chest just below my pectoral muscles. Once I have strapped the polar heart meter to my self by remote control it will link itself up to the running machine.
After I have done this I will do my five different work rates three times, and after two minutes of exercise I shall take a reading to measure my heart rate with the polar heart rate monitor. Then after each two-minute exercise I will have recovery time and as my recovery rate varies due to the intensity of the exercise I do, I will not do another experiment until my heart rate has returned to the normal heart rate for myself. Once it has returned I will do another experiment until I have completed all my ranges and I will do each experiment in the same method as above.
Interpretation of results: I can conclude that as I increase the work rate or speed (Km/h) that my heart rate increases (Bpm). This heart rate will come across by chemoreceptors and baroreceptors in blood vessels. The chemoreceptors will detect a change in the pH of the blood, and when exercise occurs it detects drops in pH as more carbon dioxide is being produced. Where as the baroreceptors detect changes in pressure and when the pressure drops because the muscles need more blood, to give them oxygen the baroreceptors detect it.
These two receptors will send a message along the nervous system to the medulla to the inhibitory center. Then the medulla sends a message along the nervous system to the sino-atrial node in the heart, this will also send a message to the adrenal gland. The adrenal gland will send adrenalin to the heart by the conary artery. This regulates the heart rate by making sure that there is a constant supply of oxygen by increasing the heart rate. This occurs at it’s maximum when there is an oxygen debt.
When there is an oxygen debt the heart will increase it’s beats per minute to stop the build up of lactic acid and it will take away the carbon dioxide and exhale the carbon dioxide via the lungs. This all increases the respiration rate and as the respiration rate increases so does the heart rate as the heart needs to pump oxygen to the muscles as exercise increases and the heart needs to get rid of the waste product, carbon dioxide. This all would happen because the heat has a self-regulated heartbeat, controlled by a pacemaker. Stimulation of the heart independent of the nervous system is called myogenic stimulation.
The myogenic stimulation starts at sino-atrial node with a cardiac impulse. This impulse travels down the atrial myocardium, and reaches the atrioventricular node. The atrioventricular node delays the impulse to allow completion of atrial contraction. The impulse then spreads down the bundle of His and branches off in purkinje fibres. Then this impulse will cause ventricular systole where the ventricles contract. This shows how my pulse was created and when the cardiac pacemaker changes the pace of the heart it changes the beats per minute and that is why the heart rate increases.