Lab 8 - Lesson 15 - Lab report PDF

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Lesson 15 Aerobic Exercise Physiology

Computer #6 Arthur Lembong- Subject Max Davison-Kerwood- Analyst Mercedes Erpelding- Analyst Tim Spychalla- Analyst

Tuesday Lab Section 002 November 15, 2016

Hypothesis It is hypothesized that an individual who is an athlete will have a greater oxygen capacity than someone who doesn’t exercise. It is also hypothesized that the body temperature on the skin will decrease with exercise. We also hypothesized that the heart rate would increase after exercise. It is hypothesized that during exercise, the QRS complex decreases and the P wave increases. It is also hypothesized that the T magnitude shortens and decreases in magnitude during exercise. It is hypothesized that after 60 seconds of rest, the values returned to normal values that were collected before exercise. Finally, it was hypothesized that pulmonary airflow increased after exercise.

Specific Aims In this experiment, we recorded and compared changes in pulmonary airflow before, during and after brief periods of moderate exercise, recorded and compared changes in respiratory rate and changes in heart rate before, during and after the exercise period, compared and noted any changes in Lead II electrocardiogram before, during and after moderate exercise, and recorded and compared changes in skin temperature associated with brief periods of moderate exercise and recovery.

Background The ability to exercise depends on if the body is able to supply an increased amount of energy to the skeletal muscles. Skeletal muscle relaxation and contraction requires chemical energy from ATP from metabolism. Chemical energy is found in proteins, carbohydrates, fats and many other things found in food. The energy that humans intake through food can’t be directly used for contraction and relaxation in muscles. Therefore, that is where the ATP comes into importance, by using some of the energy during metabolism to form ATP. Exercise increases the demand for ATP and skeletal muscle fibers store very little ATP so fast replenishment of ATP is important for exercise to continue. ATP is replenished by the transferring of the energy in creatine phosphate with phosphate to ADP. Due to this reaction, a dietary creatine supplement can slightly increase the ability to perform short-term high intensity exercise, but creatine can only supply energy for a brief period of time. After a few seconds, ATP generated during glycolysis and oxidative phosphorylation provides contraction and relaxation energy. Anaerobic glycolysis is a process that doesn’t require oxygen and it generates a small a small amount of ATP and hydrogen as glucose is metabolized to pyruvic acid. In the presence of adequate oxygen, pyruvic acid is converted to acetyl CoA. The hydrogen that was produced before is oxidized to water, which is known as oxidative phosphorylation. In addition ADP is phosphorylated resulting in the formation of a large amount of ATP. If there isn’t enough oxygen present, pyruvic acid is converted to lactic acid, a metabolite that enters the extracellular fluid increasing its acidity. After exercise, lactic acid is taken up by the muscle and converted back to pyruvic acid and metabolized to form ATP.

Glucose from intramuscular glycogen, a polymer of glucose and circulating free fatty acids are the major exercise energy substrates. Amino acid usage is very low at any work intensity. During mild or moderate exercise fat is the primary energy source for contracting muscle. Increased sympathetic stimulation accelerated the breakdown of fat, which increases the circulating levels of glycerol and fatty acids. Fatty acid metabolism yields about two times as much ATP as metabolism of an equivalent quantity of amino acid and body fat stores are relative to the demands of energy prolonged mild exercise. The mild exercise can continue as long as oxidative metabolism continues. Small amounts of ATP are also generated without exercise through glycolysis and dephosphorylation of creatine phosphate during mild exercise. During moderate to heavy dynamic exercise maintenance of the adequate amount of ATP is also dependent of glycolysis and metabolism of the glycogen-derived glucose. When the intramuscular glycogen stores are depleted, exhaustion occurs. Therefore, capacity for sustained work depends upon the amount of stored glycogen from person to person and also depending on activity and diet. Sustained exercise at any level of intensity is oxygen dependent. This allows steady-state exercise intensity to be measured in terms of oxygen consumption. Oxygen consumption increases with increasing intensity of the exercise until a plateau is reached. A highly trained athlete tends to have a greater consumption of oxygen in comparison to others who don’t exercise. The consumption peak for oxygen is limited to the ability of the respiratory and cardiovascular systems to deliver oxygen to skeletal muscle and its ability to utilize its oxygen. Maximal cardiac output and maximal oxygen use in fiber can be increased through training. Pulmonary ventilation increases linearly with work intensity during mild and moderate work and with a steeper slope in intense exercise. During dynamic exercise, increases in both tidal volume and breathing frequency contribute to increasing ventilation. Increased ventilation maintains oxygen partial pressure and hemoglobin saturation unchanged in arterial blood even in intense exercise. In light to moderate exercise, increased ventilation also maintains a rate of carbon dioxide excretion that matches the increased rate of carbon dioxide production of skeletal muscle to keep blood PH normal. In dynamic exercise there is an increase in cardiac output, increased mean arterial pressure, increased skeletal muscle and coronary arterial blood flow, and decreased blood flow in the kidneys, skin and abdominal viscera. Dynamic exercise increases sympathetic neural activity and decreases parasympathetic neural activity. Increased sympathetic neural outflow increases heart rate, cardiac contractility and stroke volume, which promotes an increase of blood delivery to skeletal muscles. Increased sympathetic neural outflow also vasoconstricts arterioles, which increases arterial mean pressure. MAP is the prime force governing blood circulation. Local chemical changes, which are the result of an increase in muscle metabolism, can override the sympathetic effects and cause vasodilation of the arterioles that supply the muscles. The vasodilation decreases vascular resistance, which coupled with MAP and peripheral vasoconstriction in other organs, which

increases blood flow and facilitates oxygen delivery and the removal of carbon dioxide. Moderate dynamic exercise oxygen delivery, removal of carbon dioxide and other metabolites by the blood are adequate to meet the metabolic demands. In exercise with intensity and duration above 50% of peak oxygen consumption, more oxygen is consumed then what can be delivered through the blood. ADP and inorganic phosphate concentrations increase as the creatine phosphate levels fall. The muscle fibers reach their limit of aerobically generation ATP. Exercise also increases the metabolic production of heat and the excess heat must be dissipated to the external environment. Balancing heat gain and loss controls core body temperature. Heat loss mechanisms involve losing heat through the skin and the airways. The most effective way to dissipate heat is to evaporate liquids to gases. Sympathetic neural outflow increases sweat production, which is stimulated during exercise.

Methods In this experiment, we used BIOPAC airflow transducer, a disposable mouthpiece, a bacteriological filter, a nose clip, temperature transducer, tape, electrode lead set, 3 disposable electrodes, electrode gel, student lab system, computer system and a stopwatch. The subject was Tim Spychalla who is a 27-year-old male that weighs 160 pounds and is 5’10”. When asked what his stress level was, he rated it at a 2 out of 10. First, the computer was turned on and the airflow transducer was plugged into channel 1, electrode lead set was plugged into channel 2 and temperature transducer was plugged into channel 3. Then the subject’s personal filter and mouthpiece was inserted into the inlet side of the transducer. The electrodes were placed on the subject with the white lead on the right shoulder, the black lead on the right abdomen and the red lead on the left abdomen. Then the subject was to tape the temperature transducer to their right fingertip. Then the hardware was calibrated by preparing the subject with a nose clip. Then they held the transducer with the left hand while sitting still. Then the subject breathed normally for calibration. Then the subject’s maximum heart rate was calculated for exercise. Then data was collected while the subject was breathing normally. After 20 seconds, the recorder pressed F2 and then the subject began exercising. Then the subject exercised until their maximum heart rate was reached. When the subject began to sweat F3 was pressed, when the intensity of exercise changed F4 was pressed and when the subject stopped exercising F5 was pressed. Then data was collected for an additional 5 minutes. After data collection, the data was analyzed. First, the data was zoomed into for the area from 0 to just after the first event marker. Then using the I-Beam cursor, the area of one complete breath cycle was selected after the two-second mark. Then the airflow amplitude, breathing rate, skin temperature and heart rate were recorded. Then all those values were recorded for 30-second intervals during the exercise portion and post exercise.

Discussion For our subject, it was observed that the airflow amplitude during exercise was significantly higher than during the subsequent recovery period; the amplitude during exercise was 4.436 liters/sec and during the recovery period the amplitude dropped to 2.957 liters/sec. Pulmonary airflow is not synonymous with pulmonary ventilation. Airflow amplitude is a volumetric rate of how much air is moving into and out of the lungs at any given time; pulmonary ventilation is the volume of ventilated air moved into and out of the respiratory system in one minute. The pulmonary ventilation is calculated by multiplying one’s tidal volume by rate of respiration. The respiratory rate and the heart rate were both found to be higher during exercise than post exercise. This makes sense because during exercise the muscles’ demand for oxygen and glucose increases in order to maintain ATP production. Increases in heart rate increase oxygen and glucose delivery as well as increase the rate of carbon dioxide removal. Also, in order to get more oxygen to the muscles, the respiratory rate increases. It took approximately 200 seconds for heart rate, respiratory rate and pulmonary airflow to return to pre-exercise levels once our subject stopped exercising. One of the most noticeable changes in the ECG waveform was the R-R interval. This interval shortened as our subject began exercising and then gradually lengthened during the recovery period. This result makes sense because heart rate increases during exercise (and drops after exercise) and the heart rate and the length of the R-R interval are inversely related. Before exercise, skin temperature was 90 degrees. During exercise, the skin temperature dropped significantly, especially around the time where the subject started to sweat. After exercise, the skin temperature gradually increased again (although in a slower rate), to the starting temperature. This is expected because during exercise the body has the sweating mechanism to decrease the body heat in order to prevent overheating of the body during exercise. During exercise, it is recommended not to wipe off sweat, as it will help cool down the body through evaporative cooling. As sweat changes from liquid phase to the gaseous phase, it absorbs heat from the body. Wiping sweat from the skin prevents heat to escape through this mechanism, which is why wiping off sweat is ill advised if body temperature needs to be maintained in a low temperature. The cellular process most responsible for fulfilling the ATP requirements of exercising skeletal muscles is glycogenolysis, anaerobic respiration. Anaerobic respiration produces oxygen debt, which is the amount of oxygen needed to process the lactic acid that is produced and released during anaerobic respiration. The existence of an oxygen debt explains why we continue to breathe deeply and quickly for a while after exercise. A high oxygen debt is associated with a low blood pH because a low blood pH implies a high concentration of acidic molecules within the

blood (both lactic acid and carbonic acid). A larger amount of oxygen is required to process the acidity and thus oxygen debt increases with a decrease in blood pH. Dynamic exercise increases cardiac output by increasing sympathetic innervation to the heart. Sympathetic stimulation increases both the stroke volume and the rate of contraction, both factors lead to an increase in circulation. In addition to sympathetic influence, local chemical changes resulting from increased muscle metabolism increase vasodilation. An increase in vasodilation reduces the resistance to flow and also contributes to an increase in cardiac output. Four cardiovascular responses to dynamic exercise, many of which were mentioned previously, include: an increase in stroke volume and heart rate resulting from an increase in sympathetic innervation to the heart; an increase in vasodilation within the skeletal muscles involved in the exercise that results from local metabolic increases; and a decrease in the resistance of the peripheral vasculature.

Conclusion In this lab we recorded and compared the changes in pulmonary airflow and respiratory rate of our subject while they rested, exercised and then recovered from exercise. In addition to these parameters, we also noted changes in the ECG waveform and skin temperature while our subject exercised. Many of our hypotheses were unconfirmed or invalided; we did not test numerous subjects and thus we cannot confirm whether an athletic individual would have a greater oxygen capacity regardless of how obvious this should be. Our hypotheses regarding the QRS complex were false, the amplitude of the wave actually increased during exercise. In hindsight this makes sense because the greater contractility of the heart during exercise would produce a greater electrical current. Lastly, our hypothesis that parameter values would return to baseline after 60 seconds turned out to be false; the recovery time was closer to 200 seconds.

References Pflanzer, Richard, J.C. Uyehara, and William McMullen. (2006) “Lesson 15: Aerobic Exercise Physiology Introduction.” Biopac Student Lab Manual. BIOPAC Systems, Inc., Santa Barbara, CA. p. 1-4....