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 Com petition Exercise Time 6 60 5 40 4 40 3 20 2 1 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 electrolytes: Na, K, P, Cl  <60 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:

H 3 C H 3 C CH 3 OH H 3 C CH 3 H 3 C OH H 3 C H 3 C O O Methandienone O Methenolone O 4-Androstene-3,17-dione

Why are these hormones of interest?

Do steroids really work? i.e. improve muscle mass and performance? . . .

A resounding Yes . . .

H 3 C OH H 3 C O Testosteron e H 3 C H 3 C HO And rosterone O

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

 – Use at own risk, < upper limit – Maybe toxic, maybe ok? – Try for min. 6 weeks?, evaluate

Added Fitness???