Study Guide for Midterm 2

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KIN 100
Barry Braun

KIN MIDTERM #2 STUDY GUIDE: Factors that determine the ratio of carbohydrate to fat use during exercise: 1. Intensity *Most Important 2. Duration *Most Important 3. Genetics/Gender 4. Environment (Heat, Cold, Altitude) 5. Diet and Supplements Tradeoff between intensity and duration: High intensity (fast, hard) = a lot of glycogen BUT duration is low Low intensity (slow, easy) = little glycogen use As exercise intensity goes UP, CHO goes up and fat goes down As exercise duration goes UP, CHO goes down and fat goes up The contribution from fat changes as exercise progresses because the rate of glycogen decreases as exercise progresses Low levels of glycogen = can’t meet energy demands = cannot maintain intensity Women use more fat at the same exercise intensity as men The largest factor: HORMONES; estrogen shifted toward more fat use, adding progesterone shifted away from fatigue Low CHO diet shifts towards more fat use- but only at LOW intensity/duration 60% maximal capacity: no difference Endurance training: -Increase ability to oxidize fat as an energy source -Training increases capillaries in the muscle ->Allow you to deliver fat to muscle ->Increase oxidative capacity and increase mitochondria During exercise caffeine decreases the need for CHO; it mobilizes triglycerides to use as energy and might lead to more uptake by muscle (triglycerides->fatty acids); habitual caffeine users see fewer benefits The Respiratory Exchange Ratio (RER) is the ratio of carbon dioxide production to oxygen consumption in one breath. Most people breathe in more oxygen than they breathe out carbon dioxide The RER determines what ratio of CHO to fats is being burned per litre of oxygen delivered. E.g. an RER of 0.9 indicates that 68% of energy is being metabolized from CHO and 32% of energy from fats *1.00 is pure CHO and .70 is pure fat The carbon dioxide concentration and oxygen ratio change in a crowded room, therefore making you dumber because of the imbalance The production of carbon dioxide increases during exercise because your body needs to respire more in order to supply the working muscles with energy The carbon dioxide production of a person during hard exercise is 15 times more than at rest (similar to that of a car, but is of course less) Gyms have such large “carbon footprints” because of A/C, lights, exercise machines, dehumidifiers, etc. People are trying to make gyms “greener” by harvesting exercise energy to grow local food The major dietary sources of protein: 1. Animal products -> amino acid ration similar (complete, similar to human needs) 2. Some plant products -> tofu (incomplete, one essential ratio low compared to human needs) 5.25g of energy are contained in amino acids; only 4.85% is available after digestion (4kcals of usable energy) *only 92-94% of PRO is digestible Energy in the nitrogen group cannot be metabolized 3-7% of total energy is contributed by protein under “normal conditions” About 9 of the 20 amino acids are essential and need to be part of diet The non-essential amino acids can be synthesized from other amino acids **KCALS FROM PRO = 20%** The ways amino acids from PRO breakdown can enter energy pathways: 1. Removal of Nitrogen from amino acid Alanine 2. Amino acids (especially branched ones) convert to Acetyl CoA Active people need more PRO to increase lean tissue, use PRO for energy when glycogen is low to repair muscle damage Nitrogen excretion is good estimate of protein use and changes with DIET but not with WORK (work=force x distance) Energy protein use is not a major source for exercise When glycogen supplies are LOW, protein contribution goes UP PRO use is much lower if glucose is consumed during exercise Anything related to lower CHO levels (hard exercise or lots of sweat) increase the contribution of PRO to energy expenditure Protein is the most misunderstood concept in sport nutrition; athletes either overemphasize or underemphasize PRO marketed as both food and diet Popularity of PRO supplements 1. Main component of muscle -> MOSTLY not true 2. Important for energy production -> MOSTLY not true 3. People don’t eat enough protein -> NOT true 4. Needs for athletes MUCH higher -> not necessarily true Supplements purified so other components are removed -> CHO, fat, vitamins, minerals **ALL PRO IS FUNCTIONAL (structural, enzymes, transporters, immune system)** Beans low in methionine; corn and rice is low in lysine “Problems” of incomplete PRO for vegans, vegetarians 2 “incomplete” proteins = a complete protein If a person were to lower their PRO excretion to a “zero protein” diet (0.4g of PRO/kg of body weight/day) they would not maintain a normal PRO balance; their body will conserve the PRO (brittle nails, recycling of AAs) 0.6 g/day is needed to maintain PRO balance in the average person This PRO intake is NOT the same as the RDA. RDA is 0.8 grams/day because it is a round number that covers 95% of the population’s requirements The RDA is NOT sufficient for athletes/active individuals. They need about 1.5 grams/day Active people require more PRO because: 1. Build lean muscle mass 2. Repair muscle damage 3. For energy when glycogen levels are low Critical Window: consuming PRO post-exercise causes MORE protein synthesis and maybe more muscle growth PRO high in leucine greater PRO synthesis. E.g. whey vs. casein Effects of caffeine on body temperature: 1. Increases the use of fatty acids for energy 2. Raises body temperatures (a bit) 3. Lowers production of ADH (Anti-Diuretic Hormone-> conserves water) Major ways the body is cooled during exercise: 1. Radiation 2. Sweating (Evaporation) 3. Conduction/Heat Exchange when air/water in contact with body 1-2.5 L/hour in sweat is lost during exercise depending on temperature and humidity; Hot & Dry= lose a lot of water in sweat Sedentary person loses ½ L/Day in sweat (17 oz)… most of their losses are as urine; minor from sweat Athletes sweat more than inactive people -> maintaining a low core temperature > hydration If dehydration is 2% of body weight means it’s critical to replace water losses; performance problems At 4% potentially get heat exhaustion, heat stroke; can no longer cool the core Cooling is different in swimmers in that they use evaporation Track fluid intake and drink enough to match estimated losses; body weight pre and post; drink a pint (or 13-16 oz) of fluid for each pound lost Difficult to completely replace fluid losses- if losing 2L water/hour the goal is to drink 1L/hour and remember to start out hydrated Preventing heat illness requires more sweating and can lead to dehydration BUT Sweating less reduces the risk for dehydration but can lead to heat illness Intermittent exercise with rest periods makes it easier to replace fluid losses Water is not the only nutrient that needs replacement: Na, K, Mg Major Electrolytes (Mineral Salts): 1. Sodium *mainly extracellular – blood plasma 2. Chloride *mainly extracellular – blood plasma 3. Potassium *mainly intracellular 4. Phosphorus *mainly intracellular Electrolytes help maintain proper fluid balance because the fluid levels inside and outside the cell are based on electric charge and otherwise you get dehydrated Part of the problem is the HIGH concentration of electrolytes (especially sodium) High electrolytes disrupt heart rhythm, muscle contraction, blood pressure and kidney function Osmolarity = electrolyte content of blood (number of molecules dissolved/unit of fluid) Osmolarity maintained in a tight range (280-300 milliosmoles/liter) Deviation from the normal range = electrolyte imbalance Changes to blood osmolarity is sensed by osmoreceptors; they sense changes in blood pressure and volume in artieries **AS YOU SWEAT YOU LOSE FLUID: 1. Blood more concentrated- osmolarity UP 2. Plasma volume DOWN 3. Blood pressure DOWN** Release of hormone from pituitary ADH causes kidney to retain water/less diuresis Changes in blood sodium expected from a severely dehydrated person: 1. ADH released (anti-diuretic hormone; helps conserve fluid and maintain osmolarity, blood volume and blood pressure) 2. Kidney reabsorbs sodium 3. Lots of sodium Overhydrating (hyponatremia) leads to LOW sodium, blood pressure and volume are too HIGH and osmolarity is DOWN **FACTORS ASSOCIATED WITH HYPONATREMIA DURING A MARATHON: 1. Relatively slow running (>4 hours to run race) 2. Drinking a lot of fluid 3. Weight GAIN (>5 pounds)** The new “endurance” sport drink has 2x the sodium and 3x the potassium to RAISE sodium levels and avoid hyponatremia NEVER give someone with hyponatremia MORE fluids Creatine is produced from amino acids and is made by liver/kidneys or animal/meat product consumption Vegetarians -> may start lower and have a greater benefit from creatine supplement (may also be true for women); leads to higher levels of creatine phosphate Creatine is stored in the liver and kidneys and is primarily in the form of phosphocreatine Creatine is good for exercise with high intensity and breaks -10 seconds cycling/20 seconds rest -Shorter the rest period, the better the creatine works -Increases capacity to rebuild creatine phosphate in rest periods Creatine is a “shuttle” -> moves high energy phosphate to the mitochondria; the more creatine you have, the faster the process; creatine is the enzyme that catalyzes the reaction **CREATINE SUPPLEMENTATION INCREASES TOTAL INCREASE MUSCLE** Bigger increase if you start lower Creatine CAN enhance exercise performance, especially intermittent, high intensity exercise Most effective when people start training Creatine allows faster re-synthesis of ATP during recovery periods because of the increase in muscle phosphocreatine; ATP is then more available to the muscle High intensity athletes are most likely to gain a performance benefit from creatine (Also maybe positive effect on mental performers such as Alzheimers or dementia; possible that creatine helps muscle “wasting” like ALS, MS or cancer) It has not been PROVEN that creatine increases muscle mass- there is definitely an increase in fat-free mass but it could be water or bone 1. Body mass tends to increase with creatine use so it is probably muscle protein 2. Do size and strength gains occur because creatine allows harder training? Side Effects of Creatine: Concern about dehydration and kidney failure, several incidents with athletes in which Creatine was blamed for injuries Eccentric exercise is when the muscle lengthens while it is producing forces and produces more damage to muscle fibers In response to muscle damage, swelling may occur called an inflammatory response (the disruption of the membrane) Rhabdomyolysis is when the membranes of muscle cells rupture and enzymes leak out Creatine kinase catalyzes the following reaction: ADP+CP-ATP+Creatine …while dietary supplements have no creatine kinase and has no creatine Muscle perimysium is a sheath of connective tissue surrounding a bundle of muscle fibers -When there is
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