Constant variable:
- I will keep the length I exercise at each speed constant. I will use 2 minutes as my constant duration of exercise.
- To make sure I run for two minutes at the same speed, I will let the treadmill equilibrate to the speed being tested by standing on the side, then start running using the handlebars. As soon as I start running my partner will immediately start the timer.
- I will start not start the next repeat or different speed until my heart rate has returned to my resting heart rate range which is 80-90 bpm (beats per minute).
- I will carry out the experiment all in the same day so that the environmental conditions such as air temperature are the same. Also my body conditions will be kept constant. For example if I did some of my experiment one day when I was feeling fit and healthy and the rest a few days later when I had a cold, my results would be affected.
Control:
The control in the experiment will be my resting heart rate.
Dependent variable:
The variable I will measure is the heart rate. I will use a heart rate monitor which will measure my average heart rate per minute. I will use a chest strap and a reader which are on the treadmills to do this. I will measure the heart rate at the different speeds for 2 minutes and record the final heart rate at the end of the 2 minutes. I will work with a partner so someone else can record the data while I do the exercise. I will use 2 minutes because I found it is the minimum time but the optimum accuracy.
I found this by running at 12 kph for one minute, two and three minutes. I found that there was not a great enough change in heart rate for one minute but at two minutes there was. For two minutes I found my heart rate go from 100 bpm to 171bpm, when for one minute there was only a 20 bpm minute change. I found that for 3 minutes there was only an extra 10bpm increase. Therefore I decided that 2 minutes would be the most accurate with the minimum time.
After exercise I will wait for 3 minutes 30 seconds until my heart rate returns to rest. I found this was the minimum amount of time it took until my heart rate returned to my rest range. Then I will do the next repeat or speed after the 3 minutes 30 seconds, this makes sure I start the next exercise at the same point throughout my experiment. I will do three repeats at each speed so I can get an average heart rate.
I will start my experiment with the high intensities first so that when I fatigue later in the experiment I will not have the high intensity speeds to do.
Safety:
- I will wear trainers with a good grip and appropriate clothing for exercise.
- I will use the safety cord on the treadmill do if I accidentally trip or fall the treadmill will turn off immediately and minimum damage is caused.
- I will make sure I do not become dehydrated during exercise and I drink plenty of water to prevent this.
Prediction:
I predict that as exercise intensity increases heart rate will increase. I predict that the maximum heart rate I will be able to reach is roughly 215 bpm because the average safe heart rate is 220 bpm minus your age.
I predict a graph similar to this with the results levelling off towards the higher intensities as maximum heart rate is reached.
Factors that effect heart rate:
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With increase in exercise there is an increase in the rate of respiration in the muscles so heart rate increases to supply the muscles with oxygen (which is carried in the blood) required for respiration and to remove the CO2.
- Increased flow to the muscles and the skin is achieved by reduced blood flow other organs such as the intestines and kidneys.
- Cardiac output is adjusted according to the demands of the body.
