The closing and opening of the semilunar and tricuspid valves results in the sound produced by the heart (lub dub), which is the heartbeat.
When we train or do any form of exercise our heart rate increases. This occurs because muscles require more oxygen to meet the high-energy requirements. As a result the heart pumps blood faster and the muscles absorb more oxygen. Since the heart pumps blood faster the heart beat increases.
List of all possible factors affecting heart rate during exercise
- Temperature: The environmental ambient temperature when performing a high intensity exercise significantly affects heart rate.
- Time of the day: the heart rate of the body is different during exercise in the morning and afternoon.
- Altitude: at high altitudes it is difficult for the body to absorb oxygen from the scare rarified air.
- VO2 max: this is the maximum amount of oxygen the body can absorb into the bloodstream. Fitter Athletes have a high VO2 max. Since they can absorb more oxygen from the air their heart rate is lower than average.
- Drugs: certain drugs like caffeine and performance enhancing steroids stimulate the heart to beat faster, absorb more oxygen and hence more energy to the muscles of athletes.
Physical fitness and stamina of an individual is important in determining his heart rate. A person who exercises regularly has a lower heart rate than an unfit person. After exercise the heart rate of the trained person comes back to normal faster
Hypothesis: As the environmental temperature increases the heart rate too increases. As the outside temperature increases the core body temperature too increases. Due to this metabolism occurs at a faster rate in body cells, which causes the heart rate to increase. However, during extreme cold conditions the heart rate too increases. In cold conditions we start shivering and our core temperature increases. Due to uncontrollable muscular activity the energy requirement to maintain the core temperature increases and so the heart rate too rises.
Independent variable: the ambient temperature during exercise
Dependant variable: the heart rate after exercise, time taken for the heart rate to return to normal
Controlled variables: altitude, humidity, distance to be covered while sprinting, time taken for the sprint, VO2 max, physical fitness and stamina of the individual, energy consumption before sprint
Fair test:
I will control my variables in the way. The altitude of the jogging track will be at seal level and all the trials will be held on the same jogging track. I will keep the humidity constant by carrying out all the original experiments and data recordings on the same day. I will conduct my experiment at the same humidity by measuring the humidity around using a hygrometer. I plan to cover an equal distance of the track at a fixed time. Per trial I will sprint 200 meters and try to keep the time to cover the distance an approximate of 30 seconds. The VO2 max, fitness and stamina will be constant because I will be the only individual who will carry out this experiment. I will train regularly before the experiment to keep my fitness levels constant and relatively high for a good result. I will plan to take sufficient readings (5) per temperature and altogether have 15 readings.
I will carry out the experiment controlling the independent variable in this way:
The experiment will take place in an indoor jogging track where the temperature is controlled by an air conditioner. I will take results at 16°C, 25°C and 35°C. For 35°C on a hot afternoon I will turn off the air conditioner and put on the night lamps, which have a heating effect.
Apparatus;
- Device to cool the room, air conditioner
- Jogging track
- Stethoscope
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Stopwatch ± 0.1 sec
Method:
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Make the temperature of the room 16°C by adjusting the air conditioner
- Record your normal heart rate either by feeling your pulse or using a stethoscope.
- On the jogging track mark a distance of 200m to be covered
- Carry a stopwatch while running and try to estimate and time your run in approximately 30 seconds.
- After the distance is covered tell someone to help you measure your heart rate either by feeling your pulse or using a stethoscope.
- Note down the heart rate immediately after the sprint is over
- Keep measuring the heart rate at regular intervals and note down the time taken for the heart rate to return to normal
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Carry out steps 2 to 7 with controlled temperatures of 25°C and 35°C
