Dr. Greene: Unit 4 Notes
Dr. Greene: Unit 4 Notes NTRI 2000-002
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This 9 page Class Notes was uploaded by Rachel Ferrell on Wednesday April 27, 2016. The Class Notes belongs to NTRI 2000-002 at Auburn University taught by Michael Winand Greene in Fall 2015. Since its upload, it has received 30 views. For similar materials see Nutrition and Health in Nutrition and Food Sciences at Auburn University.
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Date Created: 04/27/16
Rachel Ferrell NTRI 2000 Unit 4 Notes Chapter 10: Fitness • Close relationship between nutrition and physical fitness o Peak performance→needs diet with all nutrients • Physical activity = any movement of muscles o Requires energy • Exercise= specific, physical activity that is planned, repetitive, and to improve physical fitness • Benefits of physical activity→outweighs risks for most Americans 2008 Physical Activity Guidelines for America: • Adults o 150 min/week→moderate intensity o 75 min/week→ vigorous intensity or aerobic physical activity o or a combo of these two o episodes of at least 10 min spread throughout the week o the more →the beter o Muscle strengthening activities: § Major muscles groups 2 more days a week o 80% of Americans fail to achieve levels of physical activities set in these guidelines Types of Activities: • Anaerobic= without oxygen • Aerobic= with oxygen • Moderate Intensity o Increases heart rate/ breathing rate 5-‐6 on RPE scale o Brisk walk, dancing, swimming, biking • Vigorous Intensity o Aerobic, greatly increases heart/breathing rate (7-‐8 on RPE scale) o Running, tennis swimming • Muscle Strengthening o Activity that increases skeletal muscle strength, power, endurance, and mass o Ex. strength training, resistance training, endurance, etc. o Strength= max. force muscle exerts against load at one time o Endurance= repeated use of muscles before you become tired o Power= combo of strength/speed; explosive movements like jumping, throwing Flexibilty: • Increases balance/stability → reducing risk of falls/injury • =ability to move a joint through full range of motion • poor flexibility→ can lead to chronic lower back pain Intensity Level: • Heart Rate o Estimated max= 220-‐ age o Rate of Perceived Exertion Rate (RPE) Scale § Scale of 1-‐10 on what you consider your max heart rate Energy for Muscle: • ATP= chemical energy o Generated from carbs, fat, protein o Used by cells for muscle contractions o Only small amount stored in resting cells o 2-‐4 seconds worth of work stored o other sources of energy are needed • Ways to generate ATP: o Phosphocreatine (PCr) § Anaerobic § High energy compound § Formed/stored in muscle cells § PCr + ADP→ Cr + ATP § Activated instantly § Quickly restores ATP § Sustains ATP for 1 min or less o Anaerobic Glycolysis § No oxygen; from intense physical activity § 2 ATP per glucose → very ineffective § replenishes ATP quickly § BUT cannot sustain ATP production § 30 sec-‐ 2min of work § generates lactate buildup • changes acidity that inhibits glycolytic enzymes o Aerobic Glycolysis § Oxygen § Low to moderate intensity (jogging) § 28-‐30 ATP per glucose § ATP replenished slower; BUT it is sustainable § 2-‐3 min work Fuel Mixture • use→depends on intensity/ duration of exercise • high intensity o sprinting, weight lifting, (30 sec-‐2min) o oxygen is limited o primarily use carb (glucose) as substance/energy source o Glucose→ 2 pyruvate→ Lactic Acid § Anaerobic process § Gain net 2 ATP § Liver can later convert lactic acid to glucose • Low intensity o Enough oxygen o Oxygen used by mitochondria→produces ATP from the pyruvate o Can also use fat and protein (to a minor extent) to produce ATP o At this pace, can supply energy for hours • Resting o More than half of energy comes from fat o The rest comes from glucose o A small amount comes from amino acids Metabolism of Fat for Fuel: • Fat= majority of stored food in body • Triglyceride= >3 fatty acids + 1 glycerol • Fatty acid converted to ATP in mitochondria of muscle cells • Can generate 108 ATP for each 16 Carbon fatty acid chain • Trained Muscles o Have more mitochondria o Have greater ability to use fat as fuel • Prolonged Exercise o Fat becomes main fuel source • Intense Exercise: o Fat is not major source of energy o Requires more oxygen→ anaerobic Protein: Minor Source of Fuel: • If amino acids are used→most likely will be branched chain amino acids • During rest and low/moderate exercise o <5% of energy needs • During endurance exercises o 10-‐15% energy needs • Resistance exercise o Very little protein used • Average U.S. diet→ consumes plenty of protein o Therefore supplements are NOT needed Dietary Advice for Athletes: • Performance depends on o Training o Genetic makeup o Diet • Poor diet→ can hinder performance • Carbs: o Need to maintain liver/glycogen stores o Before exercise of 90-‐120 min § 1-‐2 hours before event, consume low glycemic foods o During exercise § Carbs can help improve performance o After exercise: § Restore glycogen levels by eating carbs o Carb Loading: § Beneficial for athletes with prolonged exercise routines § Week before event: • Taper down exercise • Taper up on carb diet § Potential problem= water added along wth glycogen § Can get similar benefits from consuming carbs during the competition • Protein: o Recommended= 1.0-‐1.6kg o Problem with high protein diet § Can increase Ca in urine § Increased urine production § Potential for kidney stores § If protein takes place of carbs, it could lead to early fatigue • Vitamins/Minerals o About the same for athletes and non-‐athletes o Need for antioxidants may be greater (Vitamin C/E) o Calcium § Can be lost through sweat § Especially important for female athletes § Female athletes with weird periods→ at higher risk for decreased Ca and bone fractures o Iron: § Women tend to have lower iron § Distance runners at risk→ high pressure running can break RBC and cause GI bleeding § Sports anemia= increased blood volume; temporary and shouldn’t affect performance • Fluids o Should lose no more than 2% body weight during san exercise o 2.5-‐3 cups of water should be consumes for every pound lost during exercise • Glycogen/ Glycogen Storage o Muscle glycogen→ only used by that muscle it is stored in o Liver glycogen→ released into bloodstream; used by all cells o During low /moderate intensity exercise § Glycogen stores can sustain work for up to 2 hours o Glycogen Depletion: § “Hitting the Wall” = depleted muscle glycogen § “Bonking”= depleted liver glycogen • Sports Drinks o If < 60 min exercise→Primary concern is to replenish water o If >60 min exercise → need to replenish electrolytes § Also need electrolytes if excessive sweating • Energy Bars o Good ones have carbs/protein or both o Recommended amounts § 40g carbs § <10g protein § <4g fat § <5g fiber Chapter 7: Determination of Energy Expenditure: • Direct Calorimetry= measures heat produced by the body • Indirect Calorimetry= measures oxygen consumed and carbon dioxide expired o Easier to measure o Related to what type/how much nutrients are being sued for energy Body Fat: • Varies widely (2-‐70% of body weight) • Desirable amount o Men: 8-‐24% o Women: 21-‐35% • Distribution of where fat is distributed in body does matter o Fat found in different areas or depots in the body • Methods for measuring body fat: o Water weighing= gold standard o Air Displacement (Bod Pod) o Bioelectrical Impedance o Dual Energy X-‐Ray absorptiometry (DEXA) o Skinfold thickness Nature vs. Nurture: • = genetics vs. environment • if one parent is obese→50% chance that their children will also be obese • If both parents obese→80% chance that their children will also be obese • Study: Twins in different environment o Both had same amount of body fat and distribution of body fat has a strong genetic component o 70% genetics o 30% environment • Evolutionary component? o Interactions between genes (Thrifty genes) and environment o Thrifty gene Hypothesis § Population of humans→ been through periods of feast and faine § Natural selection→ favors those carrying “thrifty alleles” § These genes promote storage of fat and energy o Environmental Hypothesis § Genetic susceptibility to obesity is not equal across ethnic groups § Selection factors: climate, thermoregulation abilities, survival advantage to living in wild § Cold adaptation→ causes increased metabolic rate § Hot adaptation→ causes decreased metabolic rate • Nurture/Environment affect o Body similarities with families→ could be due to learned behaviors o Also same with similarities between couples o Socioeconomic status affects % of obesity, especially in females Role of Leptin in Body Fat: • Fat produces hormone called leptin that decreases food intake and increases energy expenditure • Leptin is secreted in proportion to the amount of body fat • Leptin= feedback mechanism informing brain of how much fat is in body • Most Obese people→ high levels of leptin from high levels of fat o But since leptin is supposed to block food intake→ it is not working as it should o This is leptin resistance Other Hormones Regulating Food Intake • Ghrelin o Hormone from stomach that stimulates hunger o High during fasting and low after eating Weigh Control • Why should you be concerned? • A healthy weight is associated with o 1.) Longevity o 2.) Higher quality of life o 3.) Medical costs • Weight classifications o Underweight o Normal o Overweight o Obese o Extreme obesity • Methods to Asses obesity o BMI (Body Mass Index) § Based on weight and height standard § Most closely related to body fat content § Body weight(kg) / height (meters) § Body Weight (lbs) X 703/height (in) § Is BMI the best way to assess obesity? § Easy to calculate and does a good job at comparing populations o Waist circumference § Works for individuals and populations • Health Problems associated with obesity o Cardiovascular disease and stroke o Cancers→ colon, breast, prostate, ovarian, pancreatic, liver o Type 2 Diabetes o Hypertension o Gall bladder disease o Sleep apnea o Osteoarthritis • Obesity o 2/3 of Americans are overweight or obese o The increase in percentage of overweight/obese has occurred fairly recently § Suggests that it is environment of lifestyle that is cause o “Cure” for being overweight? § Change in lifestyle? Or medications? Energy Balance: • Energy in = energy out • If energy in > energy out: o Positive energy balance o Body weight/fat will increase o Required for pregnancy, infancy, childhood • If energy in < energy out: o Negative energy balance o Body weight will decrease (not just fat, but also lean mass) o Fat tissue (3500 cal/lb) o A weight loss of 1 lb per week, requires a deficit of 500 cal/day o However→ not that simple § Not a linear relationship between calories and weight loss • Energy In o = calories consumed (actually calories metabolized) o calories in a food → determined by bomb calorimeter • Energy Out o = energy expenditure o Basal Metabolic Rate (BMR) § Minimal amount of calories expended in a fasting state § Energy that it takes to be alive § 60-‐70% of total energy expenditure § 1.0 kcal/kg/hr for men; 0.9kcal/kg/hr for women (estimate) § BMR →hard to measure experimentally, so we measure the resting metabolic rate (RMR) § Factors that increase a persons BMR • More lean body mass • Larger body surface area • Being male→more lean body mass • Body temperature • Thyroid hormones • Pregnancy • Caffeine and tobacco use § Factors that decrease a persons BMR • Extreme diet→low calorie intake o Shift in conversion o Basal Metabolism (10-‐20% decrease) • Aging o Change in lean body mass o 1-‐2% decrease per 10 years past age 30 o Physical Activity § Increases energy expenditure above basal energy needs § 25-‐40% of total energy expenditure § Not exercise per se (walking around, normal activities, etc.) § Decrease in physical activity is related to todays obesity problem o Thermic effect of food § When you digest, absorb, transport, metabolize, and store nutrients→all takes energy § Think of it as energy tax on foods you consume § Also called diet-‐induced thermogenesis (DIT) § 5-‐10% of total energy expenditure o Thermogenesis § = non voluntary physical activity triggered by cold § but also→ fidgeting, maintenance of muscle tone and body posture § energy expenditure related to these activities § very small compared to other factors affecting energy expenditure § Tissue that plays an important role • Brown adipose tissue→high in mitochondria Treatment of Overweight/ Obesity • Should be long term lifestyle change • Weight Loss plan o 1.) control of caloric intake o 2.) Increase physical activity o 3.) Lifestyle changes (not easy) Popular Diet Approach Concerns: • Moderate Calorie Restriction o Concern= need acceptable vitamin/mineral supplementation • Low Carb Diet o Concern= lack of fiber→ can lead to ketosis, reduced exercise capacity, excessive fat intake can lead to GI problems and health concerns of over consumption of saturated fats • Low Fat Diet o Concern= too much fiber intake, poor mineral absorption, increased sugar/salt • Novelty Diet o Not balanced; hard to due long term; unrealistic food choices that lead to binging Professional Help Losing Weight: • Medications o FDA approved criteria o Weight loss of at least >5% a year (placebo adjusted) o OR >5% weight loss by 35% of patients o Problems→poor safety and efficacy Treatment of Severe Obesity: • BMI > 40 or 2x healthy weight • 1.) very low carb diet o 400-‐800 cal per day • 2.) Bariatric Surgery o very effective Treatment of Underweight • BMI < 18.5 • Numerous causes o Cancer, disease, excessive dieting/exercise, genetic background • Health problems o Possible loss of menstrual cycle o Low bone mass Mediterranean Diet: • Life expectancy very high in this region • Many variants of the diet→ depends on exact region/country and how close they are to actual sea • Not exactly one diet • Not just one food that contributes to the health benefits of the diet→ it’s the lifestyle Important Nutrients in Mediterranean Diet • Olive Oil o Classified on breakdown of triglycerides o Extra Virgin Olive Oil= <8% free acidity § Measured as oleic acid § Produced by mechanical means without use of solvents § Under temps that will not degrade oil (<86 degrees F) § Good for consumption of monounsaturated fats § Contains Tocopherols and phenolic compounds (powerful antioxidants) o Virgin Olive Oil= free acidity of <3 grams o Refined Olive Oil= flavorless/ odorless § Fatty acid content is unchanged Landmark Mediterranean Diet Studies: • Seven Countries Study o Observational (no actual experiment) o Prospective cohort study o Cross cultural o Led by Ancel Keys § Observed that many Americans die from heart disease while few in Naples do o 16 cohorts from 7 countries (US. Finland, Yugoslavia, Japan, Netherlands, Italy, Greece) § Contrasts in lifestyle, eating habit, risk factor levels § Various incidences of cardiovascular diseases o Measurements § Background info (lifestyle, medical history, etc.) § Physical Exam (blood pressure, heart function, etc.) § Lab Tests (Serum liquids) § Dietary Data (chemical analysis of food they were consuming) o Followed participants for 5-‐40 years o Results § Risk factors for CVD= serum lipids (cholesterols), high blood pressure § Gave insight on healthy diets § Lifestyle risk factors= physical activity, smoking o Results for healthy aging § Healthy eating pattern= less mortality § Good Mental Health = less cognitive decline § Increases prolonged physical functioning o Problems with study § Only studied men § Observational, cant control all aspects of lifestyle • The PREIMED Study o Experimental study o Clinical trial o Parallel group, multicenter, single blind, randomized trial Why such an interest in Mediterranean Diet? • Health benefits o Reduced risk of CVD, diabetes, Alzheimer’s, cancer § Because of better metabolic health o Healthy aging • Food is tasty • Food is fresh Blue Zones • = places where many people live way longer and healthier lives (100+ years old) • lessons to learn from these populations o move naturally § doesn’t take serious physical exertion, just being active daily o purpose for day/life o downshift pace of life→manage stress better o only eat until 80% full o eat more plants (**** most important one) o sense of community Community Health • Finland→ had highest rates of CVD in the world • With community/government effort o Very successful in changing lifestyles o CVD rate went extremely low
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