Both Saleh and Laurence’s breathing rates were also recorded during the 2 minute period of exercise and 60 seconds of the resting period.
After 30 seconds of exercise Laurence’s breathing rate was 12 breaths per minute. At 60 seconds of exercise Laurence’s breathing rate dropped to 5 breaths per minute, the explanation for the big difference in breathing rate at this point and the resting period could be the emotional factor of doing the exercise in front of his peers, this would modify the rate and depth of breathing from reflexes initiated by emotional stimuli acting through centres in the hypothalamus. At 90 seconds Laurence’s breathing rate 8 breaths per minute and at 2 minutes Laurence’s final reading maintained at 8 breaths per minute, Laurence’s breathing rate stabilised. Laurence then rested from exercise after 30 seconds of resting Laurence’s breathing rate increased to 12 breaths per minute and at 60 seconds of exercise his breathing rate rose to 13 breaths per minute. Another factor that could have influenced Laurence’s fluctuating breathing rate was that the pace was not kept at a constant level. Laurence could have been peddling at different speeds throughout the period of exercise.
Saleh’s breathing rate after 30 seconds of exercise was 18 breaths per minute, after 60 seconds of exercise Saleh’s breaths per minute were 17 and 90 seconds Saleh’s breathing rate rose to 20 breaths per minute. At 120 seconds Saleh’s breathing rate dropped to 15 breaths per minute, this could be because Saleh took less breaths but they were deeper. Saleh then rested at 30 seconds his breathing rate after this time was 17 breaths per minute and at 60 seconds of rest it fell to 16 seconds of rest. Saleh’s breathing rate also fluctuated but not to the same degree as Laurence’s breathing rate, Saleh’s cycling pace was also not kept at a constant rate, which could also be a factor in his unexpected fluctuating breathing rate.
As Saleh’s heart rate rose so did his breathing rate. Moderate to heavy physical exercise greatly increases the amount of oxygen skeletal muscles use. Whilst oxygen utilization is increasing, the volume of carbon dioxide produced also increases. Since decreased blood oxygen and increased blood carbon dioxide concentration stimulate the respiratory centre, it is not surprising that exercise is accompanied by an increased breathing rate, which can explain Saleh’s increased breathing rate and pulse rate. However in Laurence’s case his blood oxygen and carbon dioxide concentrations have not increased to the extent of Saleh’s during exercise, I see this as a reflection of Laurence’s respiratory system's effectiveness in obtaining oxygen and releasing carbon dioxide to the outside.
The increase in breathing rate during exercise requires an increase in blood flow to meet the needs of skeletal muscles. Thus, physical exercise increases demand on both the respiratory and the circulatory systems. If either of these systems fails to keep up with cellular demands, the person will begin to feel out of breath. This sensation however, is usually due to the inability of the heart and circulatory system to move enough blood between the lungs and the body cells, rather than to the inability of the respiratory system to provide enough air.
A number of physical factors including age, gender, exercise and body temperature influence heart rate. The average resting heart rate for males is 64-72 beats per minute. Heat increases heart rate by boosting the metabolic rate of heart cells, this accounts in parts for the effect of exercise in heart rate, as working muscles generates heat.
Both Saleh and Laurence’s breathing rates were higher than the pulse rate in the resting time. This could be because the heart speeds up initially to get the blood flow from the lungs to the muscles. As the breathing rate increases, the lungs are working faster getting more oxygen reaching the heart. The heart does not need to beat as fast as lungs are getting enough oxygen in.
As the heart rate increases, O2 is pumped faster around the body. When breathing rate increases more O2 will be taken in. In the 30 second period, the heart is told by the nervous system to beat faster followed by the lungs. If enough O2 reaches the muscles the pulse rate will slow down. Another factor is that pulse rate cannot keep increasing for ever, at a certain point the pulse rate will stabilise.
There are two receptor areas in the brain located in the medulla oblongata and pons, the cardiac centre adjusts force and the rate of heart contractions and the respiratory centre that controls rate and depth of breathing. Both respond to CO2 levels in the blood the receptors are linked to the nervous system.
Changes in levels of carbon dioxide concentrations in the blood stimulate the brain. Most carbon dioxide is transported in plasma as the bicarbonate ion. A smaller amount, between 20 and 30 percent of the transported CO2 is carried inside the red blood cells as NaHCO3 bound to hemoglobin. Before carbon dioxide can diffuse out of the blood into the alveoli, it must first be released from its bicarbontoate ion form. Carbonic acid is monitored by respiratory centre in the brain. Bicarbonate ions must enter the red blood cells where they combine with hydrogen ions (H+) to form carbonic acid (H2CO3). Carbonic acid quickly splits to form water and carbon dioxide, and carbon dioxide then diffuses from the blood and enters the alveoli. To much CO2 makes the blood to acidic and this would denature enzymes and acidosis would occur.
Heart rate is modified according to the needs of the body. It increases during physical exercise to deliver extra oxygen to the tissues and take away excess carbon dioxide. Heart rate is controlled by the SAN. The rate goes up or down when it receives information via the two autonomic nerves that link the SAN to the cardiovascular centre in the medulla of the brain. The accelerator nerve speeds up the heart, the synapse at the end of this nerve secrete noradrenaline. The decelerator nerve, a branch of the vagus nerve, slows down the heart. The synapse at the end of this nerve secretes acetylcholine.
A negative feedback system operates to control the level of carbon dioxide and indirectly oxygen in the blood. During exercise, the level of carbon dioxide starts to rise, this is detected by the Chemoreceptors situated in the carotid artery, the aorta and the medulla. When changes in pH or CO2 levels in the blood are detected by the chemoreceptor, impulses are travel down the accelerator nerve to the respiratory centre in the brain, this responds by sending more frequent impulses to the external intercorsal muscles and diaphragm. When this happens our ventilation rate increases and so the body automatically increases oxygen delivery at the same time as removing the extra carbon dioxide. When the carbon dioxide levels fall low enough, impulses pass down the decelerator nerve and the heart rate returns to normal.
The activity of the respiratory muscles the diaphragm and the external intercostal, is regulated by nerve impulses transmitted to them from the brain by the phrenic and intercostal nerves. The neutral centres that control respiratory, rhythm and depth are located in the medulla and pons. The medulla which sets the basic rhythm of breathing contains a self exciting inspiratory centre, as well as other respiratory centres. The pons centres appear to smooth out a basic rhythm of inspiration and expiration set by the medulla. Impulses going back and forth between the ponds and medulla centres maintain a rate of 12 to 15 respirations per minute this normal respiratory rate is referred to as eupnea. During exercise, we breath more vigorously and deeply because the brain centres send more impulses to the respiratory muscles. This respiratory pattern is called hyperpnea. However the rate of breathing may not be significantly increased with exercising. After strenuous exercise, expiration becomes active, and the abdominal muscles and other muscles capable of lifting the ribs are used to aid expiration.
Saleh’s resting heart rate was considerably above the average, as was his heart rate during exercise, he’s recovery rate was also slow, this could have been because Saleh is a smoker, as smoking is known to increase the heart resting rate and rate during exercise. Smoking a single cigarette increases ones heart rate, constricts peripheral blood vessels throughout the body and disrupts the flow of air to the lungs.
From smoking Saleh would have high levels of carbon monoxide present in his system as carbon monoxide preferentially binds to the haemoglobin, carbon monoxide has much greater affinity (200 – 300 times greater than oxygen) this reduces the amount of oxygen absorbed into the blood from the lungs, the carbon monoxide in the blood also reduces the amount of oxygen that is released from the blood into the muscles. Smoke inhalation has an immediate effect on respiration, increasing the airways resistance therefore reducing the amount of oxygen absorbed into the blood. Smokers can have between 2%-20% of their normal blood Oxygen taken up by Carbon Monoxide. Smoking causes chronic (or long term) swelling of mucous membranes, which also leads to an increased airways resistance. These factors have a significant effect on heart and other muscle cells where there is a high demand for oxygen, such as exercising. As Saleh’s body is not getting enough oxygen, his breathing rate increases attempting to obtain the body’s required level of oxygen at that level of physical activity.
Laurence’s resting heart rate was faster before he had begun the exercise than it was after the exercise had been completed and he had rested for one minute, this could have been because Laurence was stressed about doing the exercise in front of the class. When you are or feel threatened physically or emotionally, your sympathetic nervous system brings out the “fight-or-flight” response to help you cope with a stressful situation. One of the organs it stimulates is the adrenal medulla, which literally pumps its hormones into the bloodstream to enhance and prolong the effects of neurotransmitters of the sympathetic nervous system. Basically, the catecholamines increase the heart rate, blood pressure and blood glucose levels and dilate the small passageways of the lungs. These events result in more oxygen and glucose in the blood and faster circulation of the blood to the body organs, most importantly to the brain, muscles and heart. Thus the body is better able to deal with a short-term stressor.
There is an eleven year age gap between Saleh and Laurence, at 19 years old Laurence is at his optimum age for maximal oxygen uptake, after 25 years of age the maximum VO2 has a progressive decline in this physiologic capacity occurs, with advancing years the rate of decline is at about 1% per year, further impairing Saleh’s oxygen uptake and performance as oxygen reaching the muscles quickly is vital in performance.
The rate at which a person uses oxygen is called VO2 and is measured in terms of the volume of oxygen consumed (cm3) per kg of body mass, per minute. VO2 (max)is the maximum rate at which oxygen can be consumed and is the amount of oxygen that can be delivered to the tissues when the lungs and heart are working as hard as possible. Fitness can be measured by the volume of oxygen you can consume while exercising at your maximum capacity. VO2 max is the maximum amount of oxygen in millilitres, one can use in one minute per kilogram of body weight. Those who are fit like Laurence have higher VO2 max values and can exercise more intensely than those who are not as well conditioned like Saleh who lives a fairly sedentary lifestyle.
From Saleh and Laurence’s breathing and pulse rate results and my research my conclusion is that Laurence’s body is clearly better able to cope with physical exercise than Saleh’s. From my interpretation of the graphs and research Saleh is very unfit, this is primarily due to Saleh being a habitual smoker, additional factors include the 11 year age difference and Saleh living a sedentary lifestyle in comparison to Laurence partaking in regular exercise.
Although these results agree with my hypothesis, I do not consider this was an accurate test as there was no measurement of speed or distance that either Saleh or Laurence covered on the exercise bikes. It was impossible to measure what pace they both peddled at and whether or not the pace was at a constant speed or varied throughout the two minute period. What if Saleh covered twice the distance of Laurence, what influence would that have on the readings we measured? What if Laurence had peddled at a slower pace than Saleh, would this have increased the difference from our two studies. It could be that that Laurence peddled at twice the speed of Saleh and that Laurence is even less fit than we have estimated. The results are therefore unsafe and to get a true and accurate result we would need to conduct the exercise again, I would pre determine a distance and speed for both subjects to exercise. This would give data that was equally comparable.
