Chapter 7 & 10
Chapter 7 & 10 NTRI 2000-002
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This 9 page Class Notes was uploaded by Kaylen Taylor on Saturday April 23, 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 19 views. For similar materials see Nutrition and Health in Nutrition and Food Sciences at Auburn University.
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Date Created: 04/23/16
Chapter 10: Fitness and Nutrition Sunday, January 31, 2016 7:34 PM Relationships between Nutrition and Physical Fitness o Peak performance depends on a diet that supplies all of the needed nutrition. Physical Activity, Exercise and Physical Fitness o Not synonymous o Physical Activity: Any movement of skeletal muscles that requires energy. o Exercise: Physical Activities that are planned, repetitive, and intended to improve physical fitness. o The benefits of physical activity outweigh the risk for most Americans. o 2008 Physical Activity Guidelines for Americans o Adults should do… At least 150 minutes per week of moderate intensity. Or 75 minutes per week of vigorous-intensity aerobic physical activity Or an equivalent combination of moderate and vigorous intensity aerobic activity Episodes of at least 10 minutes, spread throughout the week. For additional and more extensive health benefits, more is better. Adults should also include muscle-strengthening activities that involve all major muscle groups on 2 or more days a week. 80% of Americans fail to achieve levels of physical activity set forth in the Physical Activity Guidelines. Types of Activities o Anaerobic vs. Aerobic o Aerobic: With oxygen o Anaerobic: Without Oxygen. o Moderate Intensity: Aerobic activity that increase's heart rate and breathing. (5-6 on RPE scale) Brisk walking, dancing, swimming, bicycling(level terrains) o Vigorous Intensity: Aerobic activity that greatly increases heart's rate and breathing (7-8 on RPE scale) Jogging, tennis, swimming, bicycling. o Muscle Strengthening Activity that increases skeletal muscle strength, power, endurance, and mass. Strength training, resistance training, muscle strength and endurance exercises. Strength: Maximal force a muscle can exert against a load at one time. Endurance: The ability of the muscle to perform repeated, submaximal contractions over time without becoming fatigued. Power: Combines strength with speed for explosive movements such as jumping or throwing. o Flexibility Exercises Enhance Balance and Stability Ability to move a joint through its full range of motion. Poor flexibility often linked to chronic pain, especially the lower back. Can improve balance, stability, thereby reducing risks of falls and injuries, especially among older adults. Intensity levels for exercise o Estimated maximal heart rate (MHR) = 200 - Age o Rating of Perceived Exertion Scale Scale of 1-10 on what you consider maximal. o Energy for Muscle Work o ATP: Chemical Energy Generated from carbs, fat, protein Used by cells for muscle contractions Only a small amount is stored in resting cells. Only 2-4 seconds worth of work Other sources of energy are needed Ways to Generate ATP o Phosphocreatine o Metabolism of Glucose (Carbs) Anaerobic glycolysis Aerobic glycolysis o Metabolism of fat o Phosphocreatine(PCr) Anaerobic metabolism mechanism High energy compound Formed and stored in muscle cells PCr + ADP ---> Cr + ATP Activated instantly Replenishes ATP Sustains ATP for one minute or less Anaerobic Glycolysis o Limited oxygen -- Intense physical activity o Produces 2 ATP per glucose About 5% of the potential energy from glucose o Replenishes ATP quickly o Not sustainable ATP production 30 seconds to 2 minutes of work o Generates lactate build-up Changes acidity that inhibits glycolytic enzymes Aerobic Glycolysis o Abundant amount of oxygen available o Produces 28 to 30 molecules of ATP o About 95% of the energy potential o Involves a complete breakdown of glucose o Sustainable ATP production 2 to 30 minutes of work o Resists lactate buildup by changing the acidity that inhibits glycolytic enzymes o The type of glycolysis used depends on the intensity and duration of the exercise. High Intensity Exercise o Sprinting, Weight-lifting, etc. o 30 seconds to 2 minutes, uses anaerobic glycolysis. o Primarily uses carbs as the energy source Low Intensity Exercise o Oxygen supply is sufficient enough to meet the demands o Oxygen is used in the mitochondria to produced more ATP from pyruvate o Fat and proteins can also be used to produce ATP when necessary. Resting o More than half of the energy the body uses comes from fat, the rest comes from glucose. Metabolizing Fat o Accounts for majority of the stored energy in the body. o Fatty acids are converted to ATP in the mitochondria o Can produce 108 ATP for each sixteen fatty acid chain. o Training muscles leads to them having for ATP and having a greater ability to use fat as fuel. Using Fat as Fuel o The rate of fat use is dependent on the concentration of fatty acids in the blood. o During prolonged periods of activities, fat becomes the main energy sources. o During intense activity, fat isn't used as a major source for energy because it requires a large amount of oxygen. Using Protein as Fuel o Used when the body is at rest or during low to moderate exercise. o Also used during endurance exercise o Branched chain amino acids provide most of the energy. Dietary Advice for Athletes o Athletic performance depends on athletic training and genetic makeup, but the proper diet can maximize potential. o A poor diet reduces potential Getting Proteins, Vitamins, and Minerals o Protein Recommended amount of 1 to 1.6 grams per kg of body weight Problems with high protein diets: Increases calcium in the urine Increased urine production Increases chances of forming kidney stones o Vitamins and Minerals Athlete needs are the same or slightly greater to that of sedentary adults Need for antioxidants may be greater Calcium: Is lost through sweat during strenuous exercise Extremely important to female athletes. Iron: Women are susceptible to low iron Distance runners are at risk; some iron is lost during sweating, red blood cells can break, and intense training can lead to GI bleeding. Fluids o Lose no more than 2% of body weight during exercise o Drink 2.5 to 3 cups for every pound lost or immediately after exercising. Glycogen/Glucose Storage o Muscle glycogen o Liver glycogen is released into the blood o During low to moderate intensity can sustain work for up to two hours o Glycogen Depletion: "Hitting a Wall" - Depleted muscle glycogen "Bonking" - Depleted liver glycogen Sports Drinks o Sports drinks that require less than 60 minutes of exertion of total weight loss is less than five to six pounds, just replace water in the body o Exercise beyond sixty minutes requires replacing carbohydrates and electrolytes Energy Bars o Uses carbs, proteins, or both o Having both in a bar seems to work better Chapter 7: Weight Control Monday, April 18, 2016 11:03 AM Weight Control o Why should you be concerned? o A healthy weight is associated with: Longevity Higher quality of Life Lower medical costs Weight Classification o Underweight o Normal o Overweight o Obesity o Extreme obesity Methods to Assess Obesity o Body Mass Index o Waist Circumference Body Mass Index (BMI) o Based on the weight for height standard o Most closely related to body fat content o BMI Body weight in kg / height^2 in meter Body weight (lbs) * 703 / height in inches o Is BMI the best way to assess obesity? o What do we use it? Are there alternatives? Can you be fat and fit? Health Problems associated with Obesity o Cardiovascular disease and stroke o Various 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 all Americans are considered to be overweight or obese. 30% are classified as obese. o The increase in the percentage has went up quickly o What does the relatively rapid increase in the number of overweight/obese people suggest? Technology Environment and lifestyles o Is there a cure for being overweight? Change in lifestyle Medications? Energy Balance o Energy in = Energy out o If Energy in > Energy out Positive energy balance Body weight will increase Required for pregnancy, infancy, and childhood Is there a limit to positive energy balance? o If Energy in < Energy out Negative energy balance Body weight will decrease Not just fat mass, but also lean mass If you want to reduce fat mass Fat tissue (3599 calories/lb) A weight loss of 1 lb per week requires a deficit of 500 calories per day. Its not that simple Energy In Energy in = calories consumed (Actually metabolized) Calories in a food can be determined by an instrument called a bomb calorimeter Energy Out Basal Metabolic Rat Basal Metabolic Rate BMR represents the 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 for men, 0,9 kcal for women Rough Estimate: 0.9 kcal/kg/hr 1.0 kcal/kg/hr Calculation 130 lbs / 2.2 lbs/kg = 59 kg 59 kg * 0.9 kcal/kg/hrs= 53 kcal/hr BMR per day: 53 kcal/hr * 24 hours = 1272 kcal per day Factors that increase a person's 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 person's BMR Extreme diet -- a low calorie intake Shift in conversion Basal metabolism (10-20%) decrease Aging Energy Out o BMR: 60-70% of total energy o Physical Activity: 25-40% of total energy o Thermal food effect: 10-20% of total energy Determination of Energy Use o Direct Calorimetry: Measures the heat produced by the body. o Indirect Calorimetry: Measures the oxygen consumed and the carbon dioxide expired. This is related to what type and how much nutrients are being used for energy. Body Fat o Varies widely in individuals (2-70% of the body weight) o Desirable amount of body fat: In Men: 8-24% In Women: 21-35% o Not only is the amount of fat important, but so is the distribution of the fat. Distribution of Body Fat o Fat is found in different areas (depots) in the body. o Can be stored around the lungs, heart, bone marrow, below the kidneys, and subcutaneous fat tissue are stored under your skin, and fat is also stored in the visceral areas (abdomen) Methods for measuring body fat o Underwater weighing (gold standard) o Air displacement (BodPod) o Bioelectrical Impedance o Dual Energy X-Ray absorptiometry o Skin fold Nature vs. Nurture o Genetics vs. Environment o If one parent is obese, there is a 50% chance that the child will be obese. o If both parents are obese, there is an 80% chance that the child will be obese. o What would you expect in twins? Identical twins raised separately ---> Suggests that 70% of the amount of body fat and distribution of body fats has a strong genetic component. o Is there an evolutionary component? It is thought that there are interactions between genes (thrifty genes) In populations that experienced feast and famine, there was a natural selection favored individual carrying thrifty alleles. These genes promoted the storage of fat and energy. o Environmental Factors Hypothesis: Suggests that there is genetic susceptibility to obesity is not equal across ethnic groups. o Selection factors: Climate Centered on the ability to thermoregulate in extreme heat or cold Survival advantage to living in the environment o Cold Adaptation Increased metabolic rate o Heat Adaptation Decreased metabolic rate Environment o Body similarities within families could be due to learned behaviors. o Similarities between couples o Socioeconomic status affects percent of obesity, especially in females. The Role of Leptin in body Weight o Fat produces a hormone called leptin that decreases food intake and increases energy expenditure o Leptin is secreted in proportion to the amount of body fat. o Thus, it appears that leptin is a feedback signal informing the brain of how much fat is in the body. o Most obese people have high levels of circulated leptin o But leptin regulates food intake, which means leptin is not working as it should. o This is called leptin resistance. Other Hormones that Regulate Food Intake o Ghrelin A hormone from the stomach that stimulates feeding and hunger Communicates in the brain Weight Treatment o Should be long term, requiring changes in lifestyle. o Weight loss plan Control calorie intake Increase physical activity Acknowledge that maintenance of a healthy weight requires lifelong changes in habits. Popular Diet Approaches & Concerns o Type of diet: Moderate calorie restriction Concern: Getting the appropriate amount of vitamins and minerals. o Type of diet: Carbohydrate focused Concern: Lack of fiber, can lead to ketosis, reduced exercise capacity; excessive fat intake can lead to GI problems and health concerns over saturated fat. o Type of diet: Low fat Concern: Too much fiber intake; poor mineral absorption, increased sugar and salt o Type of Diet: Novelty Diet (Media) Concern: Not nutritionally balanced; difficult to follow long term; unrealistic food choices can lead to binging Professional Help o Medication o FDA has to approve the drug >5% weight loss at one year or >5% weight loss by >35% of patients o Problems: Poor safety and efficacy Treating Severe Obesity o BMI > 40 or 2x healthy body weight o Very-Low-Calorie-Diets: Done exclusively at medical centers and clinics. Person must consume 400-800 calories/day o Bariatric Surgery Treatment of Underweight o BMI <18.5 o Can have numerous causes (cancer, infectious diseases, digestive disorder, excessive dieting/exercising, genetic background) o Health problems -- loss of menstrual cycle, low bone mass
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