1. Nutrition & Diet Therapy (7 th Edition) Fitness & Nutrition Chapter 10

2. Nutrition & Diet Therapy (7 th Edition) Nutrition & fitness are interactive processes—influencing each other –Energy needed to fuel activity & build lean tissue –Activity benefits nutrition Fitness: Characteristics that enable body to perform physical activity Ability to meet routine physical demands Reserve energy to rise to physical challenge Training: Regular practice of activity Leads to physical adaptations of body Improves flexibility, strength, endurance

3. Nutrition & Diet Therapy (7 th Edition) Fitness

4. Nutrition & Diet Therapy (7 th Edition) People who engage in regular physical activity live longer on average Sedentary lifestyle ranks with smoking & obesity as risk factor –Cardiovascular disease –Stroke –Hypertension –Diabetes –Some cancers Physical activity exerts a significant & pervasive influence on everyone’s nutrition & overall health

5. Nutrition & Diet Therapy (7 th Edition) Benefits of Fitness More restful sleep Better nutritional health Improved body composition Improved bone density Enhanced resistance to colds & other infectious diseases Lower risks of some types of cancers Stronger circulation & lung function Lower risks of cardiovascular disease Lower risks of type 2 diabetes Reduced risk of gallbladder disease (women) Less anxiety & depression Stronger self-image Longer life & higher quality of life Dietary Guidelines 2005 Spend an accumulated minimum of 30 minutes in some sort of physical activity most days of week

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7. Guidelines for physical fitness - Table 10-1 –Type of activity - cardiorespiratory, strength, flexibility –Frequency –Intensity –Duration

8. Nutrition & Diet Therapy (7 th Edition) The Essentials of Fitness Developing fitness –Muscle cells & tissues respond to overload of physical activity Gain strength & size—hypertrophy Disuse causes diminished size & strength—atrophy –Balanced fitness requires balanced program Stretching to enhance flexibility Weight training to develop muscle strength & endurance Aerobic activity to improve cardio-respiratory endurance –Periodic rest allows muscles time to adapt to activity

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11. The Essentials of Fitness Weight training –Builds lean body mass –Develops & maintains muscle strength & endurance –Additional benefits identified Helps prevent & manage chronic diseases, including cardiovascular disease Enhances psychological well-being Improves posture & reduces risk of back injury Helps prevent decline in physical mobility associated with aging Helps to maximize & maintain bone mass Enhances performance in other sports

12. Nutrition & Diet Therapy (7 th Edition) The Essentials of Fitness Cardio-respiratory endurance –Determines how long individual can remain active with an elevated heart rate Ability of heart & lungs to sustain a given physical demand –Characterized by Increased cardiac output & oxygen delivery Increased heart strength & stroke volume Slowed resting pulse Increased breathing efficiency Improved circulation Reduced blood pressure

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14. The Body’s Active Use of Fuels

15. Nutrition & Diet Therapy (7 th Edition) Glucose Use & Storage Stored by liver & muscles as glycogen –Liver also produces glucose from fragments of other nutrients –Glycogen stores hoarded by muscles Conserves glycogen for muscle fuel for quick action Continued activity results in release of stored glycogen (from liver) & dietary glucose to fuel muscle activity Diet effects on glycogen storage & use –Body constantly uses & replenishes glycogen –The more carbohydrate in diet, more glycogen stored in muscle— lasting longer to support physical activity

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17. Glucose Use & Storage Intensity of activity affects glycogen use –Glycogen stores more limited than fat stores –Can support daily activities But limited to <2000 kcalories of energy Fat stores can provide >70,000 kcalories –How long glycogen stores can last depends on diet & intensity of activity Moderate activities use glycogen slowly Intense activities use glycogen quickly

18. Nutrition & Diet Therapy (7 th Edition) Aerobic activity Requires oxygen Strengthens heart & lungs –Work harder to deliver oxygen to tissues Anaerobic activity Does not require oxygen May require strength –Does not work heart & lungs very hard or for sustained period

19. Nutrition & Diet Therapy (7 th Edition) Glucose Use & Storage Lactate –Produced by anaerobic breakdown of glucose during intense activity –In excess of ability of muscles to use it, converted back to glucose by liver –During intense activity, accumulates in muscle Activity duration affects glycogen use –Early in activity, muscles rely on own stores of glycogen –As muscles stores deplete, liver supplies additional glycogen –After ~20 minutes of moderate exercise, less glucose & more fat used for fuel –Glycogen depletion occurs after about 2 hours of vigorous exercise Continued exertion almost impossible “Hitting the wall”

20. Nutrition & Diet Therapy (7 th Edition) Glucose Use & Storage Maintaining blood glucose for activity –High-carbohydrate diet About 8 grams carbohydrate per kilogram of body weight –or– About 70% of energy intake –Take glucose periodically during activities lasting 45 minutes or more –Eat carbohydrate-rich foods (about 60 grams) immediately after activity –Train muscles to store as much glycogen as possible

21. Nutrition & Diet Therapy (7 th Edition) Carbohydrate loading: Regimen of moderate exercise Followed by high- carbohydrate diet Enables muscles to store glycogen above normal capacity Prepares for more intense exercise or competition

22. Nutrition & Diet Therapy (7 th Edition) Glucose Use & Storage During activity –Glycogen stores from muscle & liver dwindle during endurance activity (lasting >45 minutes) –Carbohydrate-containing drinks consumed during activity augment internal glucose supply After activity –High-carbohydrate foods after activity also enlarge glycogen stores –Consumed within 2 hours after activity –Accelerates glycogen storage by ~300% for awhile Foods with high glycemic index facilitate glycogen synthesis –Cornflakes –Mashed potatoes –Short-grain rice –Waffles –Watermelon –White bread Also referred to as “high impact carbs”

23. Nutrition & Diet Therapy (7 th Edition) Glucose Use & Storage Degree of training affects glycogen use –Factors influencing glucose use during activity Carbohydrate intake Intensity & duration of activity Degree of training –Muscles that deplete glycogen stores through work Adapt to store greater amounts of glycogen to support that work –Trained muscles burn more fat—& at higher intensities—than untrained muscles Require less glucose to perform same amount of work

24. Nutrition & Diet Therapy (7 th Edition) Fat Use During Activity “Fat loading” impairs performance –Glycogen stores depleted quickly –Athletes adhering to high- fat, low-carbohydrate diet for longer period adapt; rely more on fat to fuel activity –Benefits of high-fat diets not consistently evident May experience greater fatigue; perceive activity as more strenuous Increased risk of heart disease –Potential adverse effects makes them unwise choice Over-restriction of fat not recommended either –Endurance athletes require 20- 30% of energy intake from fat –Body fat stores important during moderate-intensity activity –Early in activity, muscles draw on fatty acids Fat stored in working muscles Fat found in fat deposits in body “Not that high-fat diets improve performance, but rather that low- fat diets inhibit performance”

25. Nutrition & Diet Therapy (7 th Edition) Fat Use During Activity Intensity & duration affect fat use –As intensity increases, fat makes less contribution to fuel activity –Fat broken down for energy only by aerobic metabolism –Longer duration results in signal to break down stored triglycerides— freeing fatty acids into blood

26. Nutrition & Diet Therapy (7 th Edition) Fat Use During Activity Degree of training affects fat use –Repeated aerobic activity produces adaptations Allows body to draw more heavily on fat for fuel Aerobically trained muscles burn fat more readily than untrained muscle Heart & lungs better able to deliver oxygen to muscles during high-intensity activity— enabling muscles to burn more fat

27. Nutrition & Diet Therapy (7 th Edition) Protein Use During Activity Protein for building muscle tissue –In hours of rest after physical activity Muscles increase rate of protein synthesis Build more of proteins needed for activity –Protein synthesis stimulated by eating high- quality protein immediately after activity –Dietary protein provides needed amino acids –However, physical activity itself is true director of muscle protein synthesis Repeated activity signals production of more proteins Protein dismantling & protein synthesis work to remodel muscles

28. Nutrition & Diet Therapy (7 th Edition) Protein Use During Activity Protein for fuel –Protein is retained; also needed for fuel –Muscles increase use of amino acids during activity –But contribute no more than 10% of total fuel used Diet affects protein use during activity –Diet is factor that regulates how much protein is used –Proteins spared from use for glucose production by diet adequate in energy & rich in carbohydrates

29. Nutrition & Diet Therapy (7 th Edition) Protein Use During Activity Intensity & duration affect protein use –Moderate-intensity & long-duration aerobic activity depletes glycogen stores Resort to use of body protein for energy –Anaerobic strength training does not use more protein for energy Demands more protein to build muscle Degree of training affects protein use –Higher degree of training, the less protein used for energy

30. Nutrition & Diet Therapy (7 th Edition) Protein Use During Activity Protein recommendations for active people –Athletes require more protein than sedentary individuals –Average protein intakes usually adequate to meet needs –Protein intake should be backed with adequate carbohydrate intake –However, different protein intakes specified for different activities

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32. Vitamins & Minerals to Support Activity

33. Nutrition & Diet Therapy (7 th Edition) Supplements Vitamins & minerals assist with release of energy from nutrients— do not provide energy About half of all athletes use supplements to improve performance –Used to greater extent by elite athletes –Use by women exceeds that of men –Supplements do not improve performance of well-nourished athletes –Deficiencies do impede performance Consumption of adequate amounts of nutrient-dense foods meets energy needs & vitamin & mineral needs Stringent weight requirements may result in poor food consumption & deficiencies –Poses risk of development of eating disorders

34. Nutrition & Diet Therapy (7 th Edition) Nutrients of Special Concern Vitamin E –Oxygen consumption by muscles increases during prolonged, high-intensity activity Enhances production of free radicals Vitamin E is antioxidant that defends cell membranes from oxidative damage –Mega doses used by some athletes to prevent oxidative damage to muscles Some evidence there may be some protection from supplementation Can receive adequate benefit from use of vegetable oils & generous servings of antioxidant-rich fruits & vegetables –Tolerable Upper Intake Level of vitamin E: 1000 mg/day

35. Nutrition & Diet Therapy (7 th Edition) Nutrients of Special Concern Iron & performance –Physically-active young women are prone to iron deficiency Engaging in endurance activities (e.g. distance running) puts athlete at greater risk Habitually low intakes of iron-rich foods, high iron losses through menstruation, high demands of muscles contribute Adolescent female athletes consuming vegetarian diet also vulnerable

36. Nutrition & Diet Therapy (7 th Edition) Nutrients of Special Concern Iron & performance (con’t) –Vegetarian diets usually rich in vitamin C Enhances iron absorption Intake of good dietary sources of iron & vitamin C-rich foods should be consumed at each meal –Iron deficiency impairs performance due to inadequate oxygen delivery, reducing aerobic work capacity (early tiring) –Sports anemia: development of low hemoglobin levels by athletes early in training Not true iron-deficiency Strenuous activity promotes destruction of fragile, older red blood cells Adaptive, temporary response to endurance training Iron-rich Foods for Vegetarians Fortified cereals Legumes, nuts, seeds

37. Nutrition & Diet Therapy (7 th Edition) Fluids & Electrolytes during Physical Activity

38. Nutrition & Diet Therapy (7 th Edition) Body’s need for water surpasses need for any other nutrient Water losses during exercise & activity –Primarily from sweating –Secondary losses from exhalation of water vapor –Losses can be significant from both routes Dehydration major threat –Loss of >2% of body weight reduces person’s capacity to do muscular work –Loss of about 7% likely to cause collapse –Fatigue is 1 st symptom For an athlete, starting a competition even slightly dehydrated presents competitive disadvantage

39. Nutrition & Diet Therapy (7 th Edition) Temperature Regulation Hyperthermia –Build up of body heat, triggering maximum sweating –In hot, humid weather, sweat may fail to evaporate; little cooling of body takes place –Heat stroke: acute & life- threatening reaction to heat build-up in body, accompanied by fluid loss Hypothermia –Loss of body heat poses as serious a threat in cold weather –Activity on cold, wet, chilly days adds to vulnerability of athlete Inadequate clothing Slow runner who produce too little heat to maintain warmth –Early symptoms Feeling cold, shivering Apathy Social withdrawal –Later signs Shivering stops Disorientation Slurred speech Change in behavior or appearance

40. Nutrition & Diet Therapy (7 th Edition) Heat Stroke Symptoms of heat stroke –Clumsiness, stumbling –Confusion, mental changes, loss of consciousness –Dizziness –Headache –Internal (rectal) temperature >104°F –Nausea –Sudden cessation of sweating (hot, dry skin) Reducing risk of heat stroke –Drink adequate fluid prior to & during activity –Rest in shade when tired –Wear lightweight clothing that allows evaporation of sweat

41. Nutrition & Diet Therapy (7 th Edition) Fluid Needs during Physical Activity Endurance athletes can lose 1.5+ quarts of fluid each hour of activity –Prepare for losses by hydration before activity –Replace losses during & after activity –In hot weather, GI absorption may not be fast enough to replace losses from sweat—some dehydration is inevitable –Hourly sweat rate: amount of weight lost plus fluid consumed per hour during exercise Preparing for competition –Drink extra fluids in last few days of training before event –Maintain hydration throughout activity Thirst is unreliable indicator of fluid balance: may become detectable only after fluid stores deplete

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43. Fluid Needs during Physical Activity Water –Plain cool water provides best drink for most individuals Rapidly leaves digestive tract to enter tissues Cools body from inside out –Endurance athletes are exception Need more from fluids than water alone Fluid replacement is 1 st priority to prevent heat stroke Carbohydrates also needed to supplement limited glycogen stores

44. Nutrition & Diet Therapy (7 th Edition) Fluid Needs during Physical Activity Electrolyte losses & replacement –Lost in sweat during physical activity Including sodium, potassium, chloride Beginners lose electrolytes to greater extent than trained athletes Regular diet usually sufficient to meet energy & nutrient needs & to replace electrolytes Activities lasting >45 minutes may require additional supplies Sodium depletion (hyponatremia) –Replenishing electrolytes critical in endurance events lasting more than 3 hours –Profuse sweating & sodium loss may cause debilitating heat cramps –Symptoms Severe headache Vomiting Bloating, puffiness from water retention Confusion, seizure –Replace sodium during prolonged events Sports drinks with higher sodium concentrations Pretzels

45. Nutrition & Diet Therapy (7 th Edition) Other Beverages Beverages to avoid during activity –Carbonated beverages Increase air in stomach, adding to feeling of fullness May result in limited fluid intake –Caffeinated beverages –Alcohol Acts as diuretic, causing further fluid, electrolyte, vitamin & mineral loss Impairs temperature regulation Alters perceptions & slows reaction time Depletes strength & endurance Impairs judgment, compromising safety

46. Nutrition & Diet Therapy (7 th Edition) Diets for Physically Active People

47. Nutrition & Diet Therapy (7 th Edition) Diets for Active People Nutrient-dense foods supply a maximum of vitamins & minerals for the energy provided Carbohydrate –Energy needs for athletes can be immense –Recommendation High carbohydrate intake (60-70% of total kcalories) Moderate in unsaturated fats (20-30%) Adequate in protein (10-20%) –Commercial high-carbohydrate liquid supplements Provide carbohydrate & energy needed for heavy training & top performance Not intended to replace regular foods Intended to be used in addition to regular diet

48. Nutrition & Diet Therapy (7 th Edition) Diets for Active People Protein –Meats & milk products are protein-rich foods –Legumes, whole grains & vegetables provide some protein along with abundance of carbohydrate Performance diet –Individual (weighing 70 kg/154 lb) engaging in vigorous activity every day may require 3000- 5000 kcalories/day –Strategy is to make sure fruit & vegetable choices are as nutrient- & energy-dense as possible

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50. Diets for Active People Pre-competition meals –Athletes may consume particular foods or practice rituals that convey psychological advantages –Specific recommendations for pregame meal Carbohydrate-rich; low in fat, protein, fiber Light in kcalories (300- 800 kcalories) Easy to digest Contain fluids –High-carbohydrate liquid meal ideas Apple juice, frozen banana & cinnamon Papaya juice, frozen strawberries & mint Fat-free milk, frozen banana & vanilla

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52. Nutrition in Practice— Supplements & Ergogenic Aids

53. Nutrition & Diet Therapy (7 th Edition) Supplements & Ergogenic Aids Athletes often receive well-intended, but unsubstantiated advice –Nutrient supplements –Drugs –Procedures that deliver results with little effort Ergogenic aids –Work enhancing or work producing –Substances or treatments that purportedly improve performance above & beyond what training can do –Research generally does not support claims of ergogenic aids

54. Nutrition & Diet Therapy (7 th Edition) Supplements & Ergogenic Aids Carnitine supplements –Carnitine is nonessential nutrient –Promoted as “fat burner” by enhancing oxidation of fatty acids –Research does not support this claim –Does produce diarrhea in about half of those using supplements –Milk & meat products provide good source Other supplements –Chromium picolinate –Creatine –Conjugated linoleic acid

55. Nutrition & Diet Therapy (7 th Edition) Supplements & Ergogenic Aids Caffeine –Some research to support use Enhances endurance Enhances short-term, high-intensity exercise performance (to some extent) May stimulate fatty acid release during endurance activity; does not slow muscle glycogen use –Other effects Stimulant that elicits physiological & psychological effects –Enhances alertness & reduces fatigue –Stomach upset, nervousness, irritability, headaches, diarrhea –Should be used in moderation In addition to other beverages Not as substitute

56. Nutrition & Diet Therapy (7 th Edition) Supplements & Ergogenic Aids Anabolic steroids (androgenic-anabolic steroid drugs) –Not safe for use by athletes Dangerous side effects Illegal to use to enhance performance –Dangers of use cannot be overemphasized Cancerous liver tumors Testicular shrinkage in men Masculinization in women Cardiovascular problems Sterility DHEA & androstenedione –Alternatives to anabolic steroids –Short-term side effects Oily skin, acne Body hair growth Liver enlargement Aggressive behavior –Long-term effects unknown

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