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Chapter 10 Nutrition: Fitness & Sports Outline Assignments Due Chemistry 80A - Class interests? Chapter 10: Nutrition: Fitness and Sports New Diet Analysis 2~ See website for assignment/details http://people.ucsc.edu/~taj/ Chem 80A Class Interests Physical Fitness “The ability to perform moderate to vigorous activity without undue fatigue” Fat usage by the body – Increased physical fitness means improved usage of fat for energy Benefits of Physical Activity Nutrition and Physical Activity Only 15% of adults are regularly physically active (U.S.) NUTRITION (intake) Physical Performance Nutrient Use Beginning an Exercise Program Start out slowly Vary your workout—Make it fun Include others—Keep accountable (notebook/log) Set attainable goals Set aside specific time (daily or weekly) Reward yourself Focus on long-term and not on occasional setbacks 2005 Dietary Guidelines for Americans 30 minutes/day physical activity – Reduce risk of chronic disease 60 minutes/day physical activity – Manage body weight and prevent weight gain 90 minutes/day physical activity – Sustain considerable weight loss Challenge Question What is your target heart rate zone? How do you calculate it? Why does it matter? Fuel for Muscle Work ATP Chemical energy – Used by cells for muscle contractions Only small amount is stored in resting cells – 2-4 seconds worth of work Other sources of energy are needed Phosphocreatine (PCr) High-energy compound – Formed and stored in muscle cells PCr + ADP Cr + ATP Activated instantly – Replenishes ATP Sustains ATP (work) for a few minutes Anaerobic Glycolysis Limited oxygen—Intense physical activity (running) Pyruvate is converted to lactate Produces 2 ATP per glucose – ~5% of energy potential Replenishes ATP quickly Cannot sustain ATP production – 30 seconds to 2 minutes of work Lactate build-up (soreness) – Changes acidity that inhibits glycolysis enzymes Aerobic Glycolysis Plenty of oxygen available (talk test) Low to moderate intensity (jogging) Produces 36-38 ATP per glucose – 95% of energy potential ATP replenished slowly Sustained ATP production – 2 minutes to 3 hours of work – Best for burning fat Glucose Utilization Glycogen Temporary storage of glucose in liver and muscle Muscle glycogen – Used only by that muscle Liver glycogen released into bloodstream During low to moderate intensity – Can sustain work for up to 2 hours “Bonking” – Depleted glycogen – Work at ~50% of maximal capacity ATP Formation Maintaining Normal Blood Glucose Level Important – For activity lasting longer than 20-30 minutes Intake of 30-60 gm carbohydrates per hour – During strenuous endurance activity – Delays fatigue by 30-60 minutes 34 grams Fat Fuel (Fatty Acid) Majority of stored energy in the body Fatty acids – Converted to ATP by muscle cells 12 ATP produced – Per each turn of the Citric Acid Cycle – 108 ATP for each 16 C fatty acid chain!!!!!!!!! Trained muscles – Have more mitochondria – Have greater ability to use fat as fuel – The more trained muscles respiring, the more fat burned – Advocate full body workout(s): dancing, swimming, biking, jogging, yoga, weightlifting, brisk walking, sports Fat Fuel Rate of fat use – Dependent on concentration of fatty acids in the bloodstream Prolonged exercise >>20 min – Fat becomes main fuel source Intense activity (e.g. sprinting) – Fat is not a major source of fuel – Requires more oxygen for aerobic breakdown (than glucose) Protein—Minor Source of Fuel During rest and low/moderate exercise – Provides 2%-5% of energy needs During endurance exercise – Provides 10%-15% of energy needs Branched-chain amino acids provide most of the energy (Leu, Isoleu, Val) Resistance exercise uses protein less Average diet – Provides ample amount of these amino acids – Supplements not needed (usually) Fuel Use During Physical Activity Calorie Needs Individual needs vary Monitoring weight and body fat – If weight falls, increase intake – If body fat increases, cut back in fat (& kcal) and maintain activity Desirable body fat for male athletes: 5%- 18% Desirable body fat for female athletes: 17%-28% Carbohydrate Needs Main fuel for many types of activity Consume ~60% of total kcal from carbohydrate > 5 gm of carbohydrate/kg body weight Aerobic and endurance athletes – 7-10 gm carbohydrates/kg body weight – ~ 500-600 gm of carbohydrates/day Carbohydrate Loading Events lasting longer than 60-90 minutes Maximize glycogen stores Tapering of exercise while increasing carbohydrate intake Additional water weight Carbohydrate (CHO) Loading Days Before Competition 6 5 4 3 2 1 Exercise Time 60 40 40 20 20 rest CHO (grams) 450 450 450 600 600 600 Fat Needs ~35% of total kcal (runner, otherwise much less . . Rich in monounsaturated fats Limit saturated fats Limit trans fat Protein Needs Recommend 1.0 - 1.6 gm protein/kg body weight Up to 1.7 gm/km body weight for athletes beginning strength training Needs are easily met by a normal diet ~ sort of – Major Protein supplements are not necessary unless attempting to build muscle mass (protein shakes) – Excessive protein has not been shown to be beneficial Current Protein Recommendations Vitamins and Minerals Vitamin E and C – Slightly higher needs – Antioxidant properties Vitamin C Thiamin, riboflavin, vitamin B-6, potassium, magnesium, iron, zinc, copper, and chromium needs – May also be higher (role in metabolism or sweat) Increase intake of fruits and vegetables Iron Needs Iron deficiency affects performance Sports anemia – Increase in plasma volume but not RBCs Women at risk because of menstruation Focus on iron-rich foods Use of iron supplement may cause toxic effects Calcium Needs Restriction of dairy products by women – not good (yogurt, cheeses) Irregular menstruation/Amenorrhea – Severe bone loss and osteoporosis – Extra calcium does not compensate for effects of menstrual irregularities – Compromises bone health Calcium deficiency increases risk of stress fractures Challenge Question What can the female athlete do to her diet and physical activity level to reestab. Monthly mensus? Fluid Needs Needs of average adults – 9 cups per day for women – 13 cups per day for men Athletes need more (depending on sweeting Maintenance of body’s cooling system – Water helps dissipate heat from working muscles Avoid losing more than 2% of body weight during exercise For every 1lb. lost replace 2.5-3 cups of fluid Confirming your knowledge -Break What are the recommended levels of protein in g/kg/body wt. for athletes? What are the recommended additional vitamin antioxidants required for athletes? Heat Exhaustion Heat stress causes depletion of blood volume due to fluid loss Body heat is dissipated through evaporation of sweat (fluid) Fluid loss (sweat): ~3-8 C per hour Humidity interferes with sweat production Dehydration decreases endurance, strength, performance Signs: Profuse sweating, headache, dizziness, nausea, weakness, visual disturbances Heat Cramps Frequent complication of heat exhaustion – Exercising in heat – Significant sweating – Consuming water without sodium Painful muscle contractions – 1-3 minutes at a time Ensure adequate salt and fluid intake Exercise moderately at first in the heat Heat Stroke High blood flow to working muscles – Overloads body’s cooling system – Sweating ceases – Internal body temperature reaches 104° F – Fatality rate high Symptoms: – Nausea, confusion, irritability, poor coordination, seizures, coma Replace fluids Monitor weight change (fluid loss) Avoid exercising in hot humid conditions Sports Drinks For Endurance Exercise Recommended for activity > 60 minutes – Help maintain blood glucose level and blood volume – Delay “bonking” Supply <60 electrolytes: Na, K, P, Cl minutes: Water adequate: – Nutrients are easily replaced by diet Gels and Bars Provide additional fuel Should be taken with fluids Expensive source of nutrients Ideal bars for endurance athletes – Contain 40 gm carbohydrate, 10 gm of protein, 4 gram fat, 5 gm of fiber – Fortified with vitamins and minerals – Toxicities possible with overuse Content of Energy Bars and Gels Confirming your knowledge After what duration of exercise are Sports drinks considered necessary for replenishment of glucose and electrolyte stores? Pre-Endurance (running) Event Meal Light meal 2-4 hours prior to event Consisting primarily of carbohydrate (top off glycogen stores) Low fat (<25% of energy intake) Little fiber (prevent bloating, gas) Moderate protein Avoid fatty, fried foods Blended or liquid meal recommended for meals eaten 1-2 hours prior Recovery Meal Carbohydrate-rich meal within 2 hours after endurance event – Glycogen synthesis is the greatest – 1-2 gm CHO/kg body weight Choose high glycemic index foods Aim for 3:1 carbohydrate-to-protein Fluid and electrolyte replacement Replenishing Muscle Glycogen Availability of adequate carbohydrate Ingestion of carbohydrate soon after exercise Selection of high-glycemic-load carbohydrate Combination of carbohydrate and protein foods Nutrition: Fitness/Sports Summary Aerobic zone for Fat burning, 120-130 BPM – Brisk walking, jogging, dancing, warrior yoga, – Stationary bike, treadmill, elliptical, (talk test) ~60% carbohydrate diet if athlete Eat simple sugar before workout (fruit, drink etc.) – Maximizes fat metabolism More PROTEIN: Athletes req. 1.0-1.7 g/kg/bdy wt. /day Vit C and E beneficial (oxidative stress) Weightlifting: focus on the eccentrics. . . Best stimuli Challenge Question> What is an ergogenic aid? And what are some examples? Ergogenic Aids Ergogenic Aids Steroid Hormones Among the synthetic anabolic steroids are: H3 C CH3 OH H3 C H3 C H3 C O OH CH3 O Methandienone Methenolone Why are these hormones of interest? Do steroids really work? i.e. improve muscle mass and performance? . . . H3 C O H3 C O 4-Androstene-3,17-dione H3 C OH A resounding Yes . . . H3 C H3 C O H3 C HO Testosteron e And rosterone Hydroxycut recall MAY 2009 The FDA has received 23 reports of serious liver injuries, including a death, linked to Hydroxycut products. SUSPECTED CULPRIT hydroxycitric acid (HCA) 1 medical study shows associated liver toxicity Laboratory and animal studies of HCA have produced results that indicate a potential for modulation of lipid metabolism hydroxycitric acid Shara et al., 2003, Mol. Cell. Biochem. 254 (1-2): 339–46 Nutrition: Fitness/Sports Controversies Any Additional Ergogenic aids???? Best natural/safe muscle building: Creatine – Add to estab. resistance training routine, not an anabolic! Hydroxycut recall Acai? 5 hour energy drinks? Rely on your own case study? – – – – – Little scientific data to back up claims. . . Try out a scientific lit. search??? Folklore/Fad Added Fitness??? Use at own risk, < upper limit Maybe toxic, maybe ok? Try for min. 6 weeks?, evaluate