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OXYGEN UPTAKE, OXYGEN DEFICIT AND OXYGEN DEBT. WORDS YOU NEED TO KNOW: Oxygen deficit Oxygen debt EPOC Steady state Anaerobic threshold Aerobic capacity Anaerobic power VO2 max Cardiac output Acute responses Cardiovascular system Respiratory system Plateau The period after the onset of exercise where oxygen consumption is below that required to produce all the ATP needed aerobically. Amount of oxygen that has to be repaid to the working muscles after an anaerobic effort has finished. There are two phases alactacid and lactacid. Recovery oxygen consumption (excess post-exercise oxygen consumption) or O2 debt The point during exercise when oxygen supply equals oxygen demand. The point at which lactic acid begins to accumulate (often expressed as occurring at 85% of MHR or 70% of VO2 max). The maximum amount of oxygen the body can take in, transport and use. Refers to the ability to produce energy (ATP) without using oxygen. The maximum amount of O2 that can be taken up, transported and utilized per minute. (Q) amount of blood ejected from the left ventricle of the heart per minute. h.r x s.v = Q A short term physiological response to a condition or exercise that is followed by a return to pre-exercise levels once the condition is removed or stopped. The system of organs (pertaining to the heart, blood vessels and blood) that is responsible for the transportation of blood around the body. The system of organs (nasal cavity, pharynx, larynx, trachea, bronchi and lungs) that makes oxygen available and carries carbon dioxide away. Commonly occurring when the body adjusts to new loads and maintenance Epinephrine Pulmonary ventilation Gas exchange / diffusion of O2 (lungs) myoglobin Mitochondria of existing conditions/ state prevails. A hormone secreted by the adrenal medulla (brain): important in regulation of arterial blood pressure. The elevated levels of the hormone epinephrine secreted during exercise increase the oxygen consumption of the body. Lung (pulmonary) ventilation (breathing). Gases diffuse from high to low pressure – O2 high in lungs low in blood and vise versa CO2 high in blood and low in lungs. Oxygen binding protein found in the muscle that attracts O2 from the bloodstream into the muscle. Powerhouse of a cell. Place where ATP resynthesis occurs and where glycogen and triglycerides are oxidized. The more mitochondria and the greater their size the greater the oxidization of fuels to produce ATP aerobically! OXYGEN INTAKE Pulmonary ventilation OXYGEN TRANSPORT Diffusion of O2 from lungs to blood Cardiac output Blood flow to the muscle OXYGEN UPTAKE Uptake of O2 by skeletal muscle (myoglobin) OXYGEN CONSUMPTION O2 used in the muscle fibre (mitochondria) Important things to note: There is a linear relationship between heart rate and oxygen consumption (therefore the greater the intensity the greater the O2 consumption) – to a point – when would this relationship stop? It is possible to work at 110% VO2 max because this indicates that the athlete is working anaerobically – remember VO2 max is the maximum amount of O2 that can be taken in, transported and utilized per minute! Think about VO2 MAX test (previous student)– towards the end he was supplying ATP anaerobically and had gone above his VO2 MAX. The tester stopped him because she could see that he was no longer supplying ATP aerobically. The 3 systems that need to work together for aerobic ATP production are the respiratory, cardiovascular and muscular systems. Most ACUTE responses that occur when exercising occur simply to deliver extra oxygen to support ATP production. They occur at the muscular, respiratory and cardiovascular levels just like chronic adaptations. They include a reduction in CP stores, accumulation of lactic acid, and increase in epinephrine, a reduction in glycogen stores, an increase in muscle temp and an increase in cardiac output. Blood is redistributed to the active muscle and to the skin and heart and redirected from the liver, kidneys and digestive tract. All of the acute responses depend on the intensity, duration and type of activity, which muscles specifically are used, how much muscle mass is involved, the type of muscle contraction and the level of fitness of the athlete. Resynthesise ATP and PC Lots of biochemical processes require O2 in recovery – some are quick others take longer Resythesise lactate back to glycogen EPOC Restore oxygen to myoglobin and blood Oxidise lactate Physical activity ATP must be constantly supplied for muscle contractions to continue during physical activity ATP is supplied by the: Aerobic system Lactic Acid system CP system As a consequence of using the energy systems acute responses occur ↓ CP stores ↑ cardiac output ↑ respiration rate ↑ heart rate Redistribution of Q ↑ lactic acid levels ↓ glycogen stores ↑ muscle temperature ↑ secretion of epinephrine ↑ supplies of ATP An oxygen debt is incurred O2 recovery consumption (EPOC) levels remain elevated until body returns to pre exercise levels The additional O2 is used to: Convert lactic acid to pyruvic acid Convert pyruvic acid to glucose in the liver Restore CP stores Help energy systems recover Resting levels again Steady state – level of O2 consumption = demand! After this point if high intensity work continues to increase the demand for O2, the acute circulatory and respiratory responses cannot act quickly enough to satisfy the demand for O2 therefore the athlete begins to produce ATP anaerobically. QUICK QUIZ 1. Which of the following gives a correct path of blood when flowing around the body? a. LV, LA, RV, RA and tissues b. LV, tissues, lungs, RA, RV, LA c. LV, lungs, RA, RV, tissues, LA. d. LV, tissues, RA, RV, lungs, LA. 2. a. b. c. d. Blood leaves the left ventricle through a blood vessel called the: pulmonary artery pulmonary vein aorta vena cava 3. The quantity of oxygen carried by the blood depends on its combining with which of the following: a. hydrochloric acid b. carbonic acid c. myoglobin d. haemoglobin 4. In a normal blood pressure reading the larger figure refers to: a. the pressure on the walls of the arteries at the moment of ventricular contraction b. the pressure on the cardiac muscle c. the pressure on the walls of the veins during contraction of the heart d. the pressure on the walls of the arteries at the moment of relaxation of the heart muscle. 5. The basic difference between veins and arteries in the systemic circuit is that: a. veins carry a higher proportion of O2 b. many veins contain valves that prevents backflow of blood c. blood pressure is lower in the arteries d. the wall of the vein is thicker and stronger than that of the corresponding artery. 6. In which of the following vessels does blood have the highest concentration of oxygen? a. pulmonary vein b. pulmonary artery c. venules d. superior vena cava 7. a. b. c. d. In the lungs exchange of gases occurs in the: bronchii bronchioles alveoli trachea 8. a. b. c. d. An individuals aerobic capacity is reflected by his / her: maximal oxygen uptake skeletal muscle density systolic blood pressure respiratory rate 9. a. b. c. VO2 max refers to: the maximum amount of oxygen you can breathe out in one breath. The size of your lungs The maximum amount of oxygen you can consume and utilize in your body per minute d. The relationship between tidal volume and the rate of breathing. 10. The degree to which the transfer of oxygen from blood to muscle tissue occurs is reflected in: a. cardiac output b. diastolic blood pressure c. haemoglobin uptake d. arterio-venous oxygen difference 11. When your heart rate levels out during sub-maximal exercise, this indicates: a. oxygen availability is sufficient to meet the energy demands b. a high level of fitness c. the lactic acid is restricting muscle contraction d. that muscle glycogen stores have been depleted. 12. Two individuals, one trained athlete (resting heart rate 50 bpm) and the other a relatively sedentary person (resting heart rate 75 bpm), both work sub-maximally on a bike ergometer at the same workload for 15 minutes. Both are the same weight. Once a steady state has been attained: a. the trained athlete would have a higher heart rate b. the untrained person would have a higher heart rate c. their heart rates would be the same d. their heart rates would be dependent upon their respiratory rates. 13. During recovery from exercise our oxygen consumption continues above resting levels for a considerable time. The initial phase of the oxygen debt lasting for 2-3 minutes is the: a. alactacid debt component, concerned with removal of lactic acid b. lactacid debt component, concerned with the removal of lactic acid c. lactacid debt component, concerned with the restoration of PC and ATP d. alactacid debt component concerned with the restoration of PC and ATP. 14. The period where the oxygen uptake is less than that required for the amount of work being performed is called: a. oxygen deficit b. oxygen debt c. steady state d. glycogen fatigue 15. Which of the following is the best example of oxygen deficit? a. the marathon runner sparing himself over the first 10kms. b. The 400m runner feeling his legs growing heavy in the home straight c. The 100m runner breathing heavily for minutes after the race d. The sprinter running his race without needing to breathe. 16. Increased amounts of myoglobin in muscles occurs due to training. This would be beneficial in aerobic activity because myoglobin: a. provides energy to form ATP b. facilitates the diffusion of oxygen from the blood to the mitochondria c. is the muscular part of the heart, and a stronger heart enables faster blood circulation d. will enable a quicker diffusion of oxygen from the lungs to the blood. QUIZ ANSWERS 1D, 2C, 3D, 4A, 5B, 6A, 7C, 8A, 9C, 10D, 11A, 12B, 13D, 14A, 15B, 16B. Cover Peak Performance Questions 2,4,6,7,9,10,12,14 and EQ 1 & 2 Notes Q2 a. 3 immediate changes – therefore meaning acute changes and watch that it only asks for changes from the cardiovascular system, not muscular and respiratory!! Increased Heart rate Increased SV Increased Q b. Respiratory only! Increased ventilation Increased pulmonary diffusion Increased inspiration and expiration volumes Increase in tidal volume Q4 a. and b. Lungs Facilitate the exchange of O2 and CO2 from the air to the blood Increased gas exchange due to increased respiration rate; increased activation of alveoli Heart Pumps O2 filled blood and CO2 rich blood around to the body and the lungs increased heart rate Capillaries: Responsible for gas exchange at the muscles and organs Increased gas exchange at the muscles = increased aVO2 diff, increased activation of capillaries Blood Haemoglobin component of blood carries O2 around the body to the working muscles Increased speed of flow, increased systolic blood pressure, more blood flow to the working muscles, decreased flow to non essential organs e.g. stomach, possibly increased blood flow to skin for cooling c. 1. The acute respiratory responses – increased ventilation, gas diffusion or oxygen uptake 2. The acute circulatory responses – increased Q, SV, h.r, venous return, blood flow to the working muscles, blood pressure, aVO2 diff. 3. The acute muscular responses – increased contractions, temperature, O2 extraction, enzyme activity, blood flow to the working muscles and decreased ATP /PC stores, muscle glycogen and triglycerides. 6 a. As he goes through each stage his O2 consumption rises. From start to the last 2 kms it rises 5.27 l/min. b. Because of the intensity, duration and muscle mass involved in the 20km walk. Additional demands could be: increases in intensity, oxygen uptake, transport, extraction and consumption all rise. c. Supply meets demand. The athlete is typically working aerobically, with aerobic glycolysis fuelling the muscles. It can take several minutes to reach SS because of HR, RR and circulation, which all need time to move from resting levels to that required to meet the demand. Q7 a. ↑ heart rate ↑ SV ↑Q ↑ gas diffusion ↑ ventilation rate ↑ a-VO2 diff Vasodilation Reduce blood flow to inactive organs Increased blood flow to working muscles Q9 a. Q10 a. b. c. d. Q12 a. b. Skeletal muscle – to provide O2 for aerobic glycolysis, skin for cooling, heart to meet the additional demands for pumping blood around the body The relationship shows that as the treadmill grade increases so too does O2 consumption. It is a linear relationship could say – increased heart rate, SV, Q or tidal volume Yes Level of O2 consumption does not level out until 7% treadmill grade. SS is not evident until this point. The high intensity work increases the demand for O2. The acute circulatory and respiratory responses cannot act quickly enough to satisfy the demand for O2. Demand exceeds supply. B Larger O2 debt, larger oxygen deficit, higher levels of oxygen consumption, doesn’t reach SS rate of oxygen uptake. c. i has lower level of O2 consumption than B ii has a smaller oxygen deficit than B iii has a smaller oxygen debt than B iv has a shorter recovery period than B Q14 A i Ii b. c. a change in intensity a change in conditions / terrain e.g a steeper gradient O2 consumption remains elevated at the end of exercise and 2 minutes into recovery is higher than oxygen consumption at rest Additional O2 is also needed for recovery of energy systems, restoration of PC, conversion of la to pa and conversion of pa to glucose in the liver. It represents O2 debt – EPOC. Exam Questions 1. a This is possible due to the involvement of anaerobic system/s. 1. b.O2 deficit is when the O2 consumption is below that necessary top provide all the energy (ATP) aerobically. 1. cThis is to allow the aerobic system to replenish the anaerobic systems. Replenish ATP – PC store and remove LA (alactacid and lactacid components of O2 debt. 2a 2b There is a finite capacity for oxygen deficit which is reached (or almost reached) in these 3 events. The rate of energy release is lower during longer events and therefore the speed is reduced. For the 1500m race, the speed is slower because the rate of energy release is less compared to that of the 400m and 800m races.