At rest, cardiac output is about 5dm3 of blood per minute.
During exercise, the heart rate increases, producing a quicker supply of deoxygenated blood to the lungs and oxygenated blood to the heart. This is because the muscles that are being used during exercise require oxygen to carry out respiration. To carry our aerobic respiration the muscles need a continuous supply of oxygen that diffuses from oxygenated blood running through nearby arteries and capillaries. When breathing, air moves into the lungs, and oxygen from the air diffuses into the arteries down a concentration gradient, and this is carried by haemoglobin in the blood to the muscles in need of oxygen. As it is used up, the breathing rate will need to increase to get more oxygen into the blood stream. As the muscles work harder to cope with the increased demand put on them, the heart will need to pump faster to pump blood to the muscles as fast as possible. Carbon dioxide is produced as a waste product of respiration, and this is toxic to the body, and cannot be allowed to build up. As the oxygen diffuses into the muscle cells, carbon dioxide diffuses out down a concentration gradient. This is carried back to the lungs where is diffuses out as we exhale. The heart needs to pump fast to remove this toxic gas too.
I predict that the direct relationship between pulse rate and exercise will be quite hard to measure as different variables will affect the pulse rate.
Some variables are:
* age
* sex
* height
* weight
* current health
* previous health history (i.e. suffer from cardiovascular or pulmonary disease
* medication
* time of day
* how much sleep the person got the night before
* what exercise has already been carried out today
* current fitness level
* time since last meal
* type of exercise
* which muscle groups are being used
* duration of exercise
* intensity of exercise
Control Methods
I will try and control as many of the variables as possible. For example, I will use a large group to get a good average of results. They shall be of the same sex and of similar age (i.e. 18-30) and weight (140-170lbs) and not suffer, or have suffered from any pulmonary or cardiovascular disease. I will ask participants to get 8 hours of sleep the night before the investigation, and also not to exercise vigorously on the day of the investigation. All participants will follow the method outlined below, so use the same muscle group, and exercise for the same duration and intensity. This should ensure that the investigation has as accurate results as so far possible.
Method
-
Measure pulse of three subjects while resting. Do this by placing fingers on the underside of the wrist, below the base of the thumb. Count each beat for 30 seconds then multiply by 2 to get beats per minute (BPM). Record in a table.
- Using a stopwatch, subjects should walk at a normal pace for 1 minute. The pulse should be measured as before, and recorded in the table.
- Subjects should rest for a minute so pulse rate returns to normal.
- After a minute, subjects should jog briskly for 1 minute. Pulse should be recorded as before
- Subjects should rest for a minute so pulse rate returns to normal.
- Subjects run at a fast pace for 1 minute, then pulse should be recorded as before.
- Subjects should rest for a minute so pulse rate returns to normal.
- Subjects run at a very fast pace for 1 minute, then pulse should be recorded as before.
Table of Results