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Midterm

CARDIO Kin 2CC3 all notes post midterm 1.pdf
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Department
Kinesiology
Course
KINESIOL 2CC3
Professor
Krista Howarth
Semester
Winter

Description
CARDIO KIN 2CC3 POST MIDTERM 1 EXAM REVIEW POST MIDTERM 1▯ ▯ Energy Contribution during Maximal Exercise▯ - the highest intensity someone can work at that would last a variety of different time points▯ - ie. exercise for 1 minute, would be the max you can do for only a minute▯ ▯ - an exercise intensity lasting one sec would be coming mostly from anaerobic, but as you increase the time you can last (reducing intensity), you rely more and more on aerobic metabolism▯ ▯ - in the first minute of exercise - majority of energy is from anaerobic systems▯ - 10 seconds = phosphagen system primarily ▯ ❖ never completely goes away▯ - 30 seconds = non oxidative glycolysis takes over mostly, some phosphagen still▯ - 30-2mins - primarily non-oxidative glycolysis▯ - 2mins - half oxidative, half anaerobic KEY TIME POINT - 50-50▯ - any exercise longer than 2 mins is providing ATP primarily from oxidative▯ ▯ why is it important to know which fuel systems are being used at different intensities/time points?▯ - for training purposes: if an individual needs to work at an event that last 2mins, they would need to make their non-oxidative systems work at a faster rate, or oxidative systems more efficient▯ *** review numbers from course pack ▯ ▯ Duration % energy (Ph/Gl/Ox) Event approx 5 sec 85/10/5 40m dash approx 30 sec 30/50/20 wingate test approx 5 min <1/20/80 1500m run 3 hr <1/<1/99 marathon ▯ Wingate Test: peak power, mean power, % fatigue▯ PP: highest power they reach in the first 5 seconds (or at all)▯ MP: the average power over the entire 30 second interval▯ %fatigue: how much of a decrease in power they had over the course of the work load▯ ▯ ▯ EX▯ PP: 1000▯ MP: 750▯ %F: 50%▯ - initially increasing curve then steady decrease throughout the test▯ - high peak power and quick percent fatigue would be good at short high intensity exercise▯ ▯ PP: 750▯ MP: 600▯ CARDIO KIN 2CC3 POST MIDTERM 1 EXAM REVIEW %F: 33%▯ - lower PP, no initial large jump, not as large a drop in power over 30 sec- these people are better at endurance sports▯ ▯ PP: 900▯ MP: 800▯ %F: 25%▯ - not only has power, but they can maintain that power▯ ▯ Out of the three examples who would win…▯ 1. 100 m dash = #1 ▯ 2. 400-800m run = #3 - their mean power is higher so they can work at a higher power and last for a long period of time, endurance person doesn’t have as high of a mean power▯ ▯ ▯ Effect of Intense Exercise on Muscle ATP, PCr, La▯ Phosphagen System▯ - starts out high, rapid drop of PCr right away.▯ - they never completely go away▯ - as we do exercise, not much happens to ATP concentration, stays constant regardless of exercise intensity - the other fuel systems constantly replenish it▯ Non-oxidative glycolysis▯ - lactate steadily increases over time and then eventually plateaus▯ - venous lactate mimicks the changes in muscle lactate, but slower to increase because the lactate is made in the muscle - takes time to get to the blood▯ - systems eventually level out once oxidative metabolism provides ATP▯ ▯ How do we determine total anaerobic energy production from muscle biopsies?▯ System Metabolite ATP yield phosphagen change in PCr - take 1 PCr = 1 ATP we can directly calculate biopsy at rest and then how many ATP were after exercise produced because it’s 1 for one Glycolytic change in lactate - not 1 lactate = 1.5 ATP (1 the change in glycogen glycogen = 2 lactate + 3 because some of it can ATP go into ox metabolism, we don’t know what went where. ▯ ** know reasonable values for any of these time points▯ ▯ Measurements Aerobic Metabolism▯ 1. Direct Calorimetry▯ ❖ measuring how many calories you’re getting, and calories equate to how much energy is being utilized ▯ CARDIO KIN 2CC3 POST MIDTERM 1 EXAM REVIEW ❖ the amount of heat produced from food can tell us how many calories are in the food▯ ❖ put them in closed environment and measure heat their body is producing over time▯ 2. Indirect Calorimetry▯ ❖ uses Spirometry: measuring breath samples, calculate how much oxygen they are consuming and how much carbon dioxide they are producing▯ ❖ the difference of what goes in and what comes out is what an individual is using▯ ❖ 2 methods: closed circuit, open circuit▯ ❖ closed circuit: how much energy one uses in a certain period of time in a closed chamber. how much energy you’ve burnt. measuring co2 and o2 levels▯ ❖ open circuit: room Co2 stays constant but what comes out of you will change, we can tell how much ATP you’re producing by looking at how what you breath out changes▯ ▯ Calorimetry: quantification of energy production by the body▯ - direct: measure of heat production▯ ❖ 1 kcal = increase temp of 1kg water by 1 degree celsius▯ ❖ calorimetric chamber: an individual does exercise in a sealed chamber▯ ❖ need expensive equipment▯ - indirect calorimetry: based on measure of oxygen utilization▯ ❖ every litre of oxygen is 5 kcal of energy▯ ❖ fuel use can also be determined▯ ❖ ventilation rate: volume of air they breathe per minute▯ ▯ RER respiratory exchange rate: rate of C02 produced to 02 consumed▯ ❖ VCO2 / V02▯ ❖ by knowing this ratio we can directly determine how much of our fuel came from fats and how much from carbohydrates▯ ❖ because RER is measured at the mouth there are some limitations▯ RER Theoretical BASIS:▯ -the O 2eeded to combust a given unit of food is constant▯ ❖ the amount of oxygen needed to burn a fuel down regardless of how many times is identical to what was needed to burn it up in the bomb calorimeter.▯ - the O 2eeded to combust a unit of carbohydrate and unit of fat is DIFFERENT▯ ❖ they use different amounts of oxygen because one requires more than the other▯ ❖ fat requires more oxygen▯ ▯ - glucose molecule: C H O6+12 O6—> 6 C2 + 6 H O▯ 2 2 - VCO /2O = 2/6 = 1.0▯ - if your body is using carbs for fuel your RER value WILL BE 1▯ ❖ no matter what it requires 6 oxygen and you produce 6 carbon dioxides▯ ❖ 38 ATP/6 O = 2.3▯ - palmitate: C 16O 3222 O —> 162O + 16H O▯ 2 2 ❖ no matter how long the chain is, you will always produce the same number of carbon dioxides as you and in the initial number of carbons▯ ❖ RER = 0.7 VCO / VO2= 16/23 ▯ RER values range from 0.7 to 1▯ ▯ RER Practical Application▯ - allows fuel mix of carbs and fat to be determined▯ CARDIO KIN 2CC3 POST MIDTERM 1 EXAM REVIEW RER %CHO % Fat kcal/ Litre of O2 1.0 100 0 5.05 0.85 50 50 4.86 0.7 0 100 4.67 anything in between is a mix of both, the farther away from 0.7 the more carbohydrate you will be using compared to fat. linear relationship▯ reasonable values are both extremes and the middle point as well.▯ - ▯ Assumptions of RER▯ - no protein contribution to oxidative metabolism▯ - we know that protein can be broken down oxidatively, but we’re assuming since we use such little amounts that it is not a large contributing factor▯ - “steady-state” conditions - there is not a large contribution from anaerobic metabolism▯ ❖ heart rate and ventilation are steady▯ ❖ high intensity exercise is not steady state▯ Limitations of RER▯ because we’re measuring difference in oxygen utilization/carbon production at the mouth, a few things can affect the value▯ - hyperventilation: VCO i2 artificially increased, your result will be over 1.▯ ❖ pulling carbon dioxide out of the bicarbonate pool, because you are causing partial pressure changes▯ - intense exercise: hydrogen ions change the pH, it makes you breathe more frequently, you breathe out more CO ▯ 2 ❖ you breathe heavy when you have too many H ions and your body wants to get rid of them▯ ❖ increased CO wi2l artificially increase RER, this value is no longer representative of carbs and fats▯ _____________________________________________________________▯ ▯ OXYGEN UPTAKE: Rest vs Maximal Exercise▯ - potential for athletic success▯ - potential for disease risk▯ ▯ OXYGEN UPTAKE: Rest▯ - refers to rate of oxygen utilization by the body▯ - VO 2 volume of oxygen consumed per minute▯ ❖ L/min or ml/min “absolute”▯ ❖ ml/kg/min “relative”▯ - “average” resting VO =20.2 - 0.3 L /min▯ ▯ ▯ ▯ = 250 ml /min▯ sometimes dividing out by body mass allows a better relative comparison, because the bigger - your body is the more oxygen it is going to use.▯ - absolute VO2 is related to body size▯ - EX: body mass of 60 might be VO2 of 200, body mass of 80 might be 300 (ml/min)▯ - relative VO2 at rest is similar▯ CARDIO KIN 2CC3 POST MIDTERM 1 EXAM REVIEW - EX: VO2 (ml/kg/min) = 3.3 for 60kg, 3.75 for 80kg person▯ - relatively speaking, resting VO2is very similar at rest▯ - **average relative resting VO 2 3.5 ml O /2kg/ min▯ ❖ this value is expressed as 1 MET = 1 metabolic equivalent▯ - WHY is MET used???▯ ➡ MET as opposed to 3.5ml / O / k2/min is used because it simplifies it▯ ❖ someone’s physician might describe different activities in terms of MET’s (gardening = 4 MET..) so someone can gauge their desired activity levels based on how many METs it is. simplified exercise prescription▯ ❖ MET is a simple resting energy expenditure, so any exercise would just be a multiple of METs▯ ▯ Resting VO : Estimating Energy Expenditure▯ 2 1. assume VO2 = 3.5ml/O2/kg/min▯ ❖ Eg 70 kg person —> 245 ml/min —> 0.245L/min =1.23 kcal / min … = 1770 kcal/day▯ ❖ ***1 L of O 2orresponds to about 5k cals of energy▯ ❖ this is assuming the average, not the most accurate method▯ 2. MEASURED VO2 = 250 ml O2 / min▯ ❖ —> .25L / min = 1.25 kcal/ min = 1800kcal▯ ❖ we can become very prescriptive on how many calories one actually needs to consume in a day. We know how many calories they are burning ▯ Which is better, high or low VO2??▯ ✦ Low VO2 at rest: if you have a low VO2 at rest you are burning less calories, might be prone to gaining weight. you are so good at converting oxygen to energy, EFFICIENT. but could make you gain weight. we try to give people to drugs so that their oxygen uptake at rest is higher and their bodies are actually less efficient. Type 1 diabetics would have a higher VO2 max.▯ ▯ Estimating Energy Expenditures: Resting VO2▯ placed under a hood and measure regular breathing.▯ - ▯ OXYGEN UPTAKE: Maximal Exercise▯ - at rest relative VO2 is very similar, relative VO2 max at maximal exercise is very different▯ - your risk for developing many cardiovascular diseases is related to VO2 max.▯ - VO2 max: ▯ ❖ maximal rate of O2 consumption by the body▯ ❖ reflects the highest rate of oxidative metabolism▯ 2 Main Determinants of Vo2 max▯ ➡ O2 delivery to muscles - cardiorespiratory system▯ ➡ O2 utlization by muscles - mitochondrial content▯ ❖ the major component of the cell that uses oxygen is the mitochondria▯ - the main determinants of VO2 max is oxygen supply▯ - some studies go back and forth, but most people would accept that delivery of oxygen to tissues is the main limiting factor▯ ▯ VO2 Max: Typical Values▯ important to know how to give an appropriate estimate value▯ - - assume 60kg female; 80 kg male▯ - Sedentary▯ CARDIO KIN 2CC3 POST MIDTERM 1 EXAM REVIEW ❖ F: 2.0L/min M: 3.0L/min▯ ❖ F: 33ml/min/kg M: 38 ml/min/kg▯ ❖ the difference in L/min is 30%, even when you divide out by body mass it’s still a difference of 15%▯ - VO2 value between men and women can be as much as 30% difference▯ ❖ guys are bigger, they require more energy▯ ❖ even when we divide out by body mass why are women still lower? - women still have lower muscle mass than guys.▯ - Active▯ ❖ F: 2.5 M: 4.0 L/min▯ ❖ F: 42 M: 50▯ - Well-trained▯ ❖ F: 3.0 M: 4.5▯ ❖ F: 50 M: 56▯ - elite▯ ❖ F: 4.0 M: 6.0▯ ❖ F: 67 M: 75▯ - when is a higher obligatory body fat an advantage? (ie women have more body fat)▯ ❖ SWIMMING: long races, this promotes buoyancy to sit higher in the water, promotes stroke. What’s a limitation in most exercises becomes an advantage in swimming▯ - CROSS COUNTRY SKIIERS: highest VO2 max values▯ ❖ almost every major muscle group is involved▯ ▯ Measurement of VO2 Max▯ - progressive increase of workload increases VO2▯ - linear relationship between VO2 and workload, the slope of the line will differ for everyone▯ - some people naturally have a very efficient gait, can contribute to submaximal values▯ - eventually the VO2 plateaus = max.▯ ▯ ___________________________________________________________▯ ▯ criteria for determining VO2 max▯ 1. plateau in VO2 is demonstrated▯ 2. reach age-predicted max HR▯ 3. high blood (lactate) concentration - 8x rest▯ ❖ lots of anaerobic metabolism is happening▯ ❖ you know you are working hard▯ 4. RER > 1.1▯ ❖ you know you are beyond 100% carbohydrate use, you are starting to breathe off excess CO2, dipped into non-oxidative metabolism.▯ 5. voluntary exhaustion▯ ▯ Rest-Work Transition: Effect of increased intensity▯ demand for oxygen goes up right away, step increase in workload▯ - ❖ your body has a set level of ATP and it step increases with work▯ - the rate of oxygen uptake doesn’t respond immediately, there is a bit of a delay so it appears as a curve, there is an oxygen deficit.▯ - the faster you increase the work, the larger oxygen deficit there will be.▯ - where does this immediate energy come from?▯ CARDIO KIN 2CC3 POST MIDTERM 1 EXAM REVIEW ❖ non-oxidative metabolism ▯ - when we are at high work intensities we are limited by PCr availability and accumulation of lactate, that’s why you can’t continue to exercise at VO2 max▯ - low intensity exercise doesn’t have that much of an oxygen deficit, high intensity is the opposite▯ ▯ how do we change the rate that we turn on the oxidative system?▯ - train ▯ ▯ The Lactate Threshold▯ - the exercise intensity at which there is an abrupt increase in blood lactate▯ - reflects ability to sustain oxidative metabolism▯ ▯ - average kin students might be around 60% VO2 max▯ - elite athletes would have it at 80% VO2 max▯ ▯ - once you go above lactate threshold, there is a linear increase of lactate in the muscle, you get to a point where the muscle shuts down.▯ - for an average individual the lactate accumulates enough to cause shut down at around 3 minutes.▯ - why you stop exercise at 150% VO2 max is for similar reasons as 3 minutes at 100% VO2 max.▯ - even though we aren’t concerned about lactate in the blood, it’s a lot easier to test for than a muscle biopsy▯ ▯ Factors affecting Muscle Lactate▯ - oxygen availability▯ - enzyme activity▯ - muscle fibre type▯ ❖ large powerful fast twitch muscle fibres produce more lactate▯ ❖ why is this good? the rate of glycolysis is higher▯ - muscle lactate transporters▯ - sympathetic nervous system activity▯ ▯ ________________________________________________________________▯ Online Lecture▯ ▯ ▯ During Exercise: Effect of Intensity▯ Four Main Fuels for Exercise▯ - all systems are on all the time, but after 2 mins it’s mostly ox. metabolism▯ 1. Muscle glycogen▯ 2. Blood glucose▯ ❖ sources of carbs from the liver (liver glycogen/glucose converted in the liver)▯ 3. Muscle Triglyceride▯ 4. Blood Fatty acids▯ ❖ triglycerides broken down from adipose tissue▯ - blood sources are coming from other supply tissues▯ ▯ CARDIO KIN 2CC3 POST MIDTERM 1 EXAM REVIEW Effect of Exercise Intensity on Fuel Selection▯ (expressed as percent of total energy)▯ - muscle TG stays constant at 15% energy the whole time▯ 25% of VO2 Max: light walking▯ ❖ 55% plasma FFA▯ ❖ 15% muscle glycogen▯ 50% of VO2 max: moderate intensity▯ ❖ 35% plasma FFA▯ ❖ 30% muscle glycogen▯ 75% of VO2 max: half an hour to 90 minutes▯ ❖ 15% plasma FFA▯ ❖ 50% muscle glycogen▯ as we progress to higher intensities of VO2 max we begin using more and more - carbohydrates as opposed to fat▯ - percentages are not always that important because tehy don’t explain absolute amount of fuels. this can be misleading▯ - as we increase intensity we use more energy, greater demand for ATP.▯ ABSOLUTE amount: rate of energy use —> Kcal/min▯ 25% of VO2 Max▯ ❖ just under 5 kcal/min▯ ❖ largest contributor: plasma FFA▯ 50% VO2 Max▯ ❖ 10 kcal/min▯ ❖ largest contributors: even split between muscle glycogen and plasma FFA▯ ❖ increased contribution of muscle TG and blood glucose▯ 75% VO2 Max▯ ❖ 15 kcal/min▯ ❖ largest contributor: muscle glycogen▯ ❖ even split between plasma FFA, muscle TG and blood glucose▯ all values go up as intensity increases▯ - - muscle glycogen sees large increase in absolute value▯ - plasma FFA: small reduction as intensity increases▯ ❖ as we increase intensity we redirect blood flow to exercising muscle, it is being sent away from adipose tissue - can’t pick up FFA that are broken down▯ ❖ harder to deliver to muscle▯ - we use as much fat as we can, but they are too slow to meet energy demand at high intensities, we need carbohydrates▯ - ** make sure to understand the difference between relative changes and absolute changes▯ ▯ How Do We Determine Rate of Energy Use??▯ EX: Kin student with VO2max of 4.0L/min▯ - 25% of max VO2 = 1.0 L/min —> recall: 5 kcal/L O2 burned▯ ❖ therefore 5 kcal/min▯ - 50% of max VO2 = 2.0 L/min▯ ❖ 10 kcal/min▯ *** need to know how to calculate this▯ ▯ Assume the student exercises for 30 minutes…▯ CARDIO KIN 2CC3 POST MIDTERM 1 EXAM REVIEW Intensity(%VO 25% 50% 75% % energy from FAT 70% 50% 30% % energy from carbs 30% 50% (RER of .85) 70% *rate of energy use 5 10 15 (kcal/min) total kcal from Fat 105 150 135 (30min x % Fat x rate total kcal from carbs 45 150 315 (30min x % CHO x rate) TOTAL ENERGY COST 150 300 450 (kcal) even though the percent contribution of fat has gone down, you are still increasing the absolute number of kcal's that fat is burning (70-50%, 105-150kcal)▯ - fats go up and back down slightly, carbs continue to go up as intensity increases▯ FUEL USE DURING EXERCISE: Effect of Duration▯ EX: 2 hours of exercise at 50% of VO2max▯ - at the beginning we see about half and half - RER of .85▯ carbohydrate sources are limited so we eventually deplete our sources▯ - - muscle glycogen decreases over the time and begins to deplete▯ - long duration exercise we can rely more on metabolic by products —> this is why blood glucose is increasing over the time, because it is transporting converted glucose from the liver▯ - eventually the unlimited source of plasma FFA are the dominant source. as long as they can meet the demand on their own, if not.. at 2 hours of exercise the liver cannot keep up with the amount of carbohydrate taken out of the liver.▯ - at the end of a marathon, blood glucose drops, your brain will stop you from exercising. you have run out of carbs and your liver cannot keep up with the demand▯ SUMMARY
 1. muscle glycogen —> goes down▯ 2. muscle TG —> goes down▯ 3. blood glucose —> goes up - bc using more liver sources of carbs▯ 4. plasma FFA —> goes up, unlimited source of fuel, once they can’t meet demand on their own, we would stop exercising▯ ▯ How do researchers determine specific fuel use?▯ 1. Measure overall rate of energy use (VO2)▯ 2. Determine % CHO and % Fat use (RER)▯ 3. Measure muscle glycogen utilization (biopsy)▯ ❖ (“other” CHO = glucose) - how much is coming from blood glucose▯ 4. Measure muscle uptake of FFA (A-V catheters)▯ ❖ arterial blood is the same all over the body▯ ❖ venous blood after the muscle, we can see how much fat comes in and out, this helps calculate how much as taken up by the muscle▯ ❖ (“other” FAT = muscle TG)▯ CARDIO KIN 2CC3 POST MIDTERM 1 EXAM REVIEW - its more difficult to measure TG in a biopsy bc.. glycogen is evenly distributed in the muscle, but fat is clumped together inside the muscle fibres, you might miss where the fat is actually being stored (marbled steak)▯ ▯ Determining Fuel Use in the Lab▯ - VO2 and RER▯ ❖ total energy: % CHO/FAT▯ - arterio-venous catheters▯ ❖ uptake of glucose of FFA▯ - muscle biopsies▯ ❖ change in glycogen or TG▯ _______________________▯ ▯ What measures are important for the performance of endurance athletes?▯ (performance VO2) - the intensity at which you can exercise for a really long time▯ - lactate threshold▯ - VO2 max▯ ▯ - people often only measure VO2 max, but there is more to it, ▯ - someone with the highest VO2 max might not win the race because they have a lower VO2 max at lactate threshold▯ - a higher LT means they can work at a higher percentage of their maximum value▯ - What determines lactate threshold?▯ ❖ lactate transporters▯ ❖ how many mitochondria you have ▯ - some people are genetically better designed▯ ▯ ______________________________________________________________▯ ▯ Hormonal Regulation of Fuel Use During Exercise▯ ▯ Neuroendocrinology▯ “the combined activity of tissues which regulate hormone release and control bodily function”▯ hormone▯ - chemical substance secreted into bodily fluids, with specific effects on local or distant target tissues▯ Sources: ▯ - endocrine glands▯ - nerve fibres (SNS)▯ - other tissues - including muscle, kidney▯ ▯ Classification▯ - peptide▯ ❖ derived from protein▯ ❖ soluble —> faster acting▯ - Steroid▯ ❖ derived from lipid (cholesterol)▯ ❖ insoluble —> slower acting▯ Major Functions Related to Exercise▯ CARDIO KIN 2CC3 POST MIDTERM 1 EXAM REVIEW - alter enzyme activity (P)▯ - alter membrane transport (P)▯ - alter protein synthesis rate (bodybuilders want faster growth of hormones) (S)▯ ▯ Hormone Site of Release Primary Action Insulin pancreas (B-cells) increase glucose/FFA/ decrease lipolysis AA uptake Glucagon pancreas a-cells increase liver ncrease glycogenolysis gluconeogenesis Epinephrine adrenal medulla increase muscle increase lipolysis glycogenolysis (muscle, adipose) Norepinephrine SNS fibres, adrenal increased lipolysis increased medulla (adipose) cardiorespiratory function we tend to see a reduction in insulin during exercise▯ - we generally see an increase in most hormones though▯ - ▯ hormone example 1: enzyme activation and fuel mobilization▯ ▯ The Cyclic AMP (cAMP) “Second Messenger” System▯ **review this page in course pack▯ - the hormone is specific to the receptor - specific to the cellular response▯ - the intermediary steps involved tend to be similar▯ - hormones play a role in metabolism but its not the critical one▯ - muscle glycogen break down: ▯ ▯ hormone example 2: stimulation of membrane transport and glucose uptake▯ type II diabetes: an inactivity related disorder▯ - ▯ ▯ Stimulation of Muscle Glucose Uptake During Exercise▯ - cheap way to treat type II diabetes▯ - if you have lots of extra glucose you can try and get rid of it by contracting your muscles which doesn’t use high insulin▯ - what are the two things that would regulate how much insulin is seen by a tissue?▯ ❖ amount of glucose in the blood▯ ❖ blood flow▯ during exercise we have changes in blood flow▯ - - REST: = [15 units] / L x 1L/min▯ ❖ = 15 units/min▯ - EXERCISE = [10 units] / L x 10L/min▯ ❖ = 100 units/min▯ ❖ we don’t want to be storing glucose in all the tissues▯ ❖ the general signal is “reduce your glucose uptake” ▯ ❖ we downregulate the signal that causes glucose to be taken up▯ ❖ the blood flow to active muscle increases a lot▯ CARDIO KIN 2CC3 POST MIDTERM 1 EXAM REVIEW ❖ the amount of insulin seen by the muscle goes up even though the blood concentration is going down▯ ▯ pg66▯ -one hormone acts on many tissues doing many different things (like CV changes, metabolism)▯ -insulin=anabolic hormone▯ ▯ -decreases in [ ] with increased exercise▯ ▯ -but amount of insulin seen by muscle increases with exercise because of (blood ▯ concentration and muscle blood flow)▯ why not just increase concentration of insulin? because we don’t want ALL tissues to see the increase in insulin and store things▯ ▯ -would still be good for active tissues but detrimental for the other tissues▯ ▯ pg67▯ -liver is the only way to replace the glucose after you use it▯ -glycogenolysis : enzyme=glycogen phosphorylase ▯ ▯ ▯ pg68▯ mitochondria: training turns on mitochondrial biogenesis▯ ▯ ▯ ^endurance ▯ ▯ fuel storage: we get an increase in GLUT4 (able to take up more glucose after we eat)▯ ▯ increase in storage enzymes▯ ▯ fuel use: to compare adaptations, must be comparing results at same absolute load▯ ▯ pg69▯ -lactate threshold is going up, lactate concentration is going down▯ _________________________▯ ▯ get thursday march 6th lecture notes / watch podcasts▯ ▯ ________________________________________________________▯ ▯ Key Components of CV system▯ - heart (pump)▯ - vasculature (tubing)▯ - blood (fluid medium)▯ Three Major CV Adjustments to Acute Exercise▯ 1. Cardiac output (Q) increased▯ 2. Q redistributed throughout the body▯ ❖ sending more of that cardiac output to the active areas and less to the inactive areas▯ 3. Tissues adjust rate of Oxygen removal from blood▯ ❖ concentration of arterial blood oxygen minus venous blood oxygen▯ CARDIO KIN 2CC3 POST MIDTERM 1 EXAM REVIEW - these are the main changes BUT▯ - *** we need to have the driving pressure through the system MAINTAINED▯ ❖ increasing blood flow without pressure would cause nothing to happen, blood flow needs to happen in the right direction▯ ▯ Anatomy of the Human Heart▯ - right and left atrium are similar▯ - right and left ventricle are different —> left ventricle needs to pump to the ENTIRE body▯ ▯ valves located b/w atrium and ventricle (tri/bicuspid or AV valves)▯ - - Valves: only open in one direction▯ ❖ like doorways that you can only go through in one direction▯ ❖ in order to open a valve we need to have greater pressure before the valve than after the valve —> pushes the valve open▯ AV valves: regulate flow within heart (b/w atria and ventricles)▯ Semilunar valves: regulate flow out of heart: pulmonary and systemic circulation▯ ▯ Electrical Conduction System of the Heart▯ - pacemaker controls the firing rate of AP▯ in order to change HR we need to have an impact on the SA node▯ - The Electrocardiogram▯ - a series of repeating waves and complexes▯ ▯ The Cardiac Cycle▯ - the events that occur between successive heart beats▯ - systole: contraction phase▯ - diastole: relaxation phase▯ - these are changes in pressure and volume▯ - where the blood is going is dictated by the pressure within the heart so we can open or close the different valves▯ rest: a typical resting HR is 75bpm (Cardiac cycle is 0.8sec)▯ - ❖ systole is 0.3sec(40%) / diastole is 0.5sec (60%)▯ - Systole: heart is contracting, diastole: heart is FILLING▯ - exercise: HR has doubled, cardiac cycle is halted (0.4sec)▯ ❖ systole is 0.25sec / diastole is 0.15 sec▯ ❖ the contraction of our heart can ONLY go so fast, we can’t change it that much▯ ❖ LESS blood is pumped out to the body▯ ❖ venous return: we send more blood back to the heart during exercise than we do at rest, venous return is blood being sent back▯ ❖ really high heart rates: our body adjusts so it can maximize filling time and still function properly▯ Phases of Cardiac Cycle▯ 1. ventricular filling▯ ❖ AV valve OPEN▯ ❖ blood in the atrium is moving easily into the ventricle▯ CARDIO KIN 2CC3 POST MIDTERM 1 EXAM REVIEW ❖ semilunar valve is closed bc the pressure in th aorta is pushing back on the valve keeping it closed▯ ❖ lower pressure in the ventricle bc it’s relaxed▯ 2. isovolumetric contraction▯ ❖ as soon as ventricle filled with blood and begins to contract the pressure inside that area will increase (squeezing a filled water balloon)▯ ❖ pressure builds up until it overcomes the pressure on the outside▯ ❖ the diameter inside the ventricle gets smaller▯ ❖ both valves are CLOSED▯ ❖ once the pressure inside becomes equal or greater than aortic pressure, the semilunar valve will open, AV valve is closed▯ 3. Ventricular Ejection▯ ❖ ventricle starts to relax, as soon as it relaxes the ventricle pressure will decrease▯ ❖ the blood in the aorta creates pressure that closes the semilunar valve▯ ❖ as the ventricle relaxes, the AV valve is also closed, NO VOLUME CHANGES bc both valves are closed▯ 4. Isovolumetric relaxation▯ ❖ pressure in the atrium needs to be higher than ventricle pressure▯ ❖ the blood coming back from the body passively at rest, actively during exercise, fills up the atrium▯ ❖ this building pressure in the atrium gets higher than the ventricle thus opening the AV valves▯ 1. AV valve open, semilunar valve closed▯ 2. iso con▯ ❖ both are closed▯ 3.AV valve closed, semi open▯ 4. iso relax▯ ❖ both closed▯ - when valves are open, pressure in both chambers is equal▯ - 15mm of mercury when full and contracting▯ as soon as ventricle begins to contract, AV is shut▯ - ** check page 80 of course pack for pressure value changes▯ - 80mm hg during iso contractions▯ ▯ Volume Changes During Cardiac Cycle▯ - during ventricular filling, heart is as full as its going to get▯ - end diastolic volume: when the heart is full▯ *** review course pack page 81▯ Pressure Changes▯ - up to 15mm mercury when completely full▯ ▯ - once pressure is equal to the aorta, the SL valve will open▯ - the ventricle is contracting during isovolumetric contraction▯ ▯ Volume Changes During Cardiac Cycle At Rest▯ CARDIO KIN 2CC3 POST MIDTERM 1 EXAM REVIEW “End Diastolic Volume (EDV)▯ - volume of blood in ventricles at end of diastole▯ - untrained person at rest typically = 120mL▯ ❖ like half of the tiny carton thing of milk▯ ❖ “pre-load” —> stretch on ventricles due to filling. the more full the heart is, the greater the stretch on the walls, the more force you can produce to get the volume out. (more filling = greater pre-load)▯ -Stroke Volume (SV)▯ - volume of blood ejected from ventricles per beat▯ - untrained at rest: 70mL▯ ❖ we don’t get rid of all the blood from our heart at rest when we pump it▯ ❖ the part that IS pumped out = ejection fraction —> 70/120 = 60% of volume of EDV is pumped out of your heart at rest. average ejection fraction for untrained▯ ❖ whatever is left over ▯ *EDV will be the highest, SV will be lower, leftover is ejection fraction ▯ ❖ 60% of EDV is SV▯ Ventricular Volumes: Effect of Exercise▯ - LeftVentricular EDV: 130mL ▯ - LeftVentricularESV: 60mL▯ - as we increase exercise intensity, our heart fills more, we get an increase in EDV▯ as we increase exercise intensity ESV goes DOWN▯ - ❖ ie we fill it more, and pump more out▯ ❖ both of these cause an INCREASED stroke volume▯ ❖ the difference between LVEDV and LVESV is SV▯ *EDV will be the highest, SV will be lower, leftover is ejection fraction ▯ ❖ 60% of EDV is SV▯ ▯ “The Muscle Pump”▯ - contraction of skeletal muscles squeezes veins and promotes venous return to the heart▯ - you are actively bringing the blood back to the heart at a faster rate when you exercise▯ you can fill the heart more than you could at rest because you are not just relying on - passive filing▯ - increasing venous return via MUSCLE PUMP▯ - EDV goes up : venous return goes up : WHY: because of muscle pump▯ ▯ Frank- starling law of the heart▯ - an increase in EDV causes stroke volume to increase▯ How do we increase the force of contraction?▯ - the more full the heart is: the more stretch on the walls of the heart : the more force there will be for the contraction▯ within physiological limits, the force generated by contracting the ventricle is greater - when the muscle is previously stretched▯ ▯ Cardiac Output (Q): at REST▯ Q = HR (beats/min) x SV (mL/beat)▯ CARDIO KIN 2CC3 POST MIDTERM 1 EXAM REVIEW -need to know how fast (HR) as well as the volume per beat▯ -at rest in untrained: average HR = 75bpm▯ ❖ male: 80 SV —> Q = 6.0 L/min▯ ❖ female: 60 SV —> Q = 4.5 L/min▯ -TRAINED at rest: cardiac output doesn’t need more blood at rest, it’s the same demand at rest▯ ❖ male: HR = 55 SV = 110 —> Q = 6.0▯ ❖ female: HR = 55 SV = 80 —> Q = 4.5▯ -with trained ppl▯ ❖ heart is bigger and stronger▯ ❖ increased SV….▯ ❖ heart doesn’t have to work as hard - reduced heart rate▯ ❖ increased ejection fraction because heart is better▯ Cardiac Output: Maximal Exercise▯ Qmax = HRmax x SVmax▯ ❖ everyone has the same max HR for age▯ ❖ SV will go up with training, higher in males than females▯ ❖ higher cardiac output with training in both genders▯ ▯ -as exercise intesntiy goes up, heart rate goes up. ▯ heart rate is the main factor that is increasing your cardiac output▯ - MIDTERM 2 REVIEW▯ -glut 1 will take up glucose at anytime, not very fast though▯ -exercise causes calcium to be released from the SR▯ ❖ that calcium can also signal glut 4 to move to the membranes▯ ❖ calcium independently recruits glut 4 to the membrane and allow us to take up glucose▯ ❖ if you are diabetic and this insulin pathway isn’t working, you can still do exercise via the contraction size▯ ❖ diabetics use calcium to still do exercise▯ -our insulin concentration goes down during exercise ▯ ❖ even tho the concentration goes down, we have a large increase in blood flow to active tissues▯ ❖ the receptors on the muscle will see more insulin EVEN THOUGH the concentration has gone down▯ ❖ during exercise, not only can you take advantage of contraction, you can also take advantage of insulin at the active tissues▯ -when the hormone binds outside the cell, it turns on a pathway inside that activates glycogen phosphorylase OR hormone sensitive lipase▯ -the muscle does not have receptors for glucagon, only epinephrine▯ ▯ _______________________________________________________▯ ▯ Using HR to predict Fitness and Training Intensity▯ -are our assumptions of HR zones good or bad? —> this gives a rough indication of optimal zones for different goals▯ CARDIO KIN 2CC3 POST MIDTERM 1 EXAM REVIEW If it’s not really true Why do we go by these charts on things like treadmills etc..▯ ▯ Variability in Max HR: Not everyone = 220-age▯ - is everyone’s max HR really 200? NO. there will be individual variability▯ - what are the advantages of having an easy formula?▯ ❖ good for general estimates▯ ❖ good for large groups▯ - based on normal physiological situations, we can estimate VO2 max, the average prescription might be correct▯ ❖ chart shows standard deviations: 68% of the population would lie within 1 SD (12bpm)▯ ❖ that means about 2/3 of the group, have a max HR of 168-192 bpm▯ ❖ now we have a huge ▯ **220 good for population, not good for individual exercise prescription▯ ▯ Using HR to Predict VO 2ax▯ ✦ WHY?▯ - assumptions: ▯ ❖ linear relationship between heart rate and workload (not always true)▯ ❖ you are an average individual (ie 220-age formula is accurate for you)▯ - procedure:▯ ❖ measure HR at 2 submaximal workloads▯ ❖ extrapolate line to predicted HR max▯ ❖ determine predicted VO2max▯ - advantages: this test is easier in terms of equipment▯ - subject doesn’t have to actually go to their max▯ - disadvantages: what if you don’t have a linear relationship? what if you are at the low end, and you reach max before you technically are assumed to?▯ ▯ Using HR to predict work intensity: “Karvonen Formula”▯ - heart rate reserve HRR = HRmax - resting HR▯ - you can’t do anything about your max HR▯ - BUT you can do something about your resting HR with fitness▯ - EX: average 20 yr old▯ ❖ (220-20) = 200-70▯ ❖ 130bpm ▯ Training HR▯ ❖ THR = resting HR + (% HRR)▯ - EX: someone wanting to work at 60% VO2max▯ ❖ 70 + (0.6 x 130)▯ ❖ 70 + 78 = 148 bpm▯ - % HRmax does NOT equal VO ma2▯ - if you are relatively healthy, you might estimate max HR▯ ❖ run a 400m as fast as you can. that allows you to get to maximal HR▯ ❖ you don’t always need fancy equipment▯ - karvonen formula lets you figure out these numbers without expensive equipment.▯ CARDIO KIN 2CC3 POST MIDTERM 1 EXAM REVIEW - %HRmax tends to underestimate workload▯ - EX: a 20 year old with resting HR = 70▯ % VO % HR max predicted THR change 60 120 148 19 80 160 174 8 90 180 187 4 if you are going below the THR you are underestimating their optimal heart rate for training.▯ - you can individualize these numbers very well with the karvonen formula▯ - there is a greater error at lower work intensities▯ ▯ Cardiac Output: Regulatory Influences▯ ✦ Chronotropic▯ ❖ rate of contraction (ie HR)▯ ❖ chronotropic drug would influence HR▯ ❖ inside the body there are neural and hormonal influences that can affect the rate of contraction▯ ❖ EX:▯ ✦ Inotropic▯ ❖ affects the strength of contraction ▯ ❖ a drug that would increase stroke volume▯ ❖ neural, hormonal and mechanical influences▯ ▯ Note:▯ - there are sympathetic and parasympathetic influences on the heart▯ - the vagus nerve directly influences the heart and the SA node▯ - lots of sympathetic control to the heart and vasculature▯ - the various tissues involved can be influenced by symp/parasymp innervation▯ - sympathetic control of vasculature: (especially the arteries) controls where the blood goes▯ - any form of norepinephrine will be the same▯ ▯ Cardiovascular Control Centre▯ - PNS(acetylcholine - vagus nerve)/SNS (norepinephrine - cardiac accelerator nerve▯ ❖ controls SA and AV node▯ - PNS slows things down▯ - SNS speeds things up▯ ❖ also innervates ventricles▯ ▯ SNS: rate, and strength of contraction▯ PNS: just affects HR▯ ▯ CARDIO KIN 2CC3 POST MIDTERM 1 EXAM REVIEW ** you would want drugs to affect SNS because then it would affect rate and strength of contraction. if they are like PNS, they would only affect rate of contraction▯ ▯ mechanoreceptors: inside the heart can affect the strength of contraction▯ ▯ Take home point: regulation of cardiac output in exercise▯ - the initial increase in HR when you start to exercise…▯ • NEURAL SIDE▯ ❖ because you are withdrawing vagal tone▯
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