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Introduction: The heart is the hardest working muscle in the body and together with the lungs they form the basis of the human respiratory system. The heart pumps oxygenated blood through the arteries to tissues and muscle. The arteries divide into smaller and smaller tubes that are as small as one cell thick called capillaries. Capillaries then join into larger tubes called veins which return deoxygenated blood back to the heart, which then pumps it to the lungs to be oxygenated which starts the whole cycle again. The blood has 3 main jobs; one is to carry water, oxygen and nutrients around the body, the second is to remove waste and CO2 from the cells and the third is to maintain body temperature. When you exercise, the heart has to pump faster to supply the muscles with enough blood to sustain them. This also increases your breathing rate because there is more blood to be oxygenated (Rickard, Phillips, Johnstone, & Roberson, 2006).

Humans get energy from aerobic respiration, which happens in cells. In this process, glucose (C6H12O6) combines with oxygen to give off CO2, H2O and energy. Sometimes, humans can perform anaerobic respiration, in which there is not enough oxygen for aerobic respiration in which glucose is released from food molecules to give off lactic acid and energy. There is much less of an energy release than aerobic respiration, for example a sprint. Anaerobic threshold is where the exercise is intense enough to the point where lactic acid is produced faster than it can be removed. An increased heart rate easily allows lactic acid to be carried away and broken down by the liver via the bloodstream (Fitness and Respiration, 2012).

Before the start of exercise breathing and heart rates increase well beyond resting heart rate. This is called an anticipatory response and is controlled by the adrenal neurotransmitter norepinephrine and the adrenal hormone epinephrine (Bozeman, 1998).

The amount of blood pumped out by the heart per minute (mL/min) is called the cardiac output and is a function of the heart rate and stroke volume. The stroke volume is the amount of blood (mL) the heart pumps out every minute. Increasing your heart rate or your stroke volume increases cardiac output. Variables that can affect the rate of your stroke rate include an increase in the amount of blood in the ventricle at the end of filling, and an increase in the sympathetic system activity. The formula for calculating what your cardiac output is:

Cardiac Output (mL/min) = Heart Rate (bpm) x Stroke Volume (mL/beat) (Doohan, 1999).

The amount of air breathed in a single breath is called the tidal volume. Exercise causes an increase because requirements for oxygen go up. An increase in tidal volume is necessary to meet the required amount of oxygen, because an increase in respiration rate is not enough (Folkl, 2011).

Aim: To investigate the effects that physical exercise has on heart and breathing rate.

Materials: For this experiment you will need; an open area allowing the freedom for all subjects to perform with the most consistency, a stopwatch and a heart rate monitor.

Risk Analysis: Risk (Hazard) | Consequences | Precautions | Dehydration | Feeling sick, light-headed, dizzy and fainting | Drinking water the night before and sipping before exercise | Injury | Pulled/torn muscle, broken bone | Stretching, conducting experiment in safe environment | Overexertion | Collapsing, fainting, dizzy, vomiting | Monitor their well-being, make sure the pace is reasonable and the subjects can keep up |

Method: Four male and female subjects of varying fitness levels were selected based on the perception of their fitness level. Subjects then measured their resting heart rates first thing in the morning over three days. The anticipatory heart and breathing rates of all subjects were recorded and put into a table. Subjects then walked at the same pace for six minutes with intervals at two minutes, four