Transcript - SlideBoom
Fitness & Nutrition Chapter 10 Nutrition & Diet Therapy (7th 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 Nutrition & Diet Therapy (7th Edition) •Training: •Regular practice of activity •Leads to physical adaptations of body •Improves flexibility, strength, endurance Fitness Nutrition & Diet Therapy (7th 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 Nutrition & Diet Therapy (7th Edition) • Physical activity exerts a significant & pervasive influence on everyone’s nutrition & overall health Benefits of Fitness • • • • • More restful sleep • Lower risks of Better nutritional health cardiovascular disease Improved body composition • Lower risks of type 2 Improved bone density diabetes Enhanced resistance to • Reduced risk of gallbladder colds & other infectious disease (women) diseases • Less anxiety & depression • Lower risks of some types • Stronger self-image of cancers • Stronger circulation & lung • Longer life & higher quality of life function Dietary Guidelines 2005 Spend an accumulated minimum of 30 minutes in some sort of physical activity most days of week Nutrition & Diet Therapy (7th Edition) Nutrition & Diet Therapy (7th Edition) • Guidelines for physical fitness - Table 10-1 – Type of activity - cardiorespiratory, strength, flexibility – Frequency – Intensity – Duration Nutrition & Diet Therapy (7th 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 Nutrition & Diet Therapy (7th Edition) Nutrition & Diet Therapy (7th Edition) Nutrition & Diet Therapy (7th Edition) 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 Nutrition & Diet Therapy (7th 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 Nutrition & Diet Therapy (7th Edition) Nutrition & Diet Therapy (7th Edition) The Body’s Active Use of Fuels Nutrition & Diet Therapy (7th 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 Nutrition & Diet Therapy (7th Edition) • 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 Nutrition & Diet Therapy (7th Edition) 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 Nutrition & Diet Therapy (7th Edition) Aerobic activity • Requires oxygen • Strengthens heart & lungs – Work harder to deliver oxygen to tissues Nutrition & Diet Therapy (7th Edition) Anaerobic activity • Does not require oxygen • May require strength – Does not work heart & lungs very hard or for sustained period 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 Nutrition & Diet Therapy (7th Edition) • 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” 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 Nutrition & Diet Therapy (7th Edition) Carbohydrate loading: • Regimen of moderate exercise • Followed by highcarbohydrate diet • Enables muscles to store glycogen above normal capacity • Prepares for more intense exercise or competition Nutrition & Diet Therapy (7th 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 Nutrition & Diet Therapy (7th Edition) • 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” Glucose Use & Storage • Degree of training affects glycogen use – Factors influencing glucose use during activity • • • – Muscles that deplete glycogen stores through work • – Carbohydrate intake Intensity & duration of activity Degree of training 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 Nutrition & Diet Therapy (7th Edition) Fat Use During Activity • “Fat loading” impairs performance – Glycogen stores depleted quickly – Athletes adhering to highfat, 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 Nutrition & Diet Therapy (7th Edition) • Over-restriction of fat not recommended either – Endurance athletes require 2030% 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 lowfat diets inhibit performance” 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 Nutrition & Diet Therapy (7th 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 Nutrition & Diet Therapy (7th 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 highquality 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 Nutrition & Diet Therapy (7th 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 Nutrition & Diet Therapy (7th 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 Nutrition & Diet Therapy (7th 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 Nutrition & Diet Therapy (7th Edition) Nutrition & Diet Therapy (7th Edition) Vitamins & Minerals to Support Activity Nutrition & Diet Therapy (7th 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 Nutrition & Diet Therapy (7th 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 Nutrition & Diet Therapy (7th 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 Nutrition & Diet Therapy (7th 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 Nutrition & Diet Therapy (7th Edition) Fluids & Electrolytes during Physical Activity Nutrition & Diet Therapy (7th 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 1st symptom • For an athlete, starting a competition even slightly dehydrated presents competitive disadvantage Nutrition & Diet Therapy (7th 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 & lifethreatening reaction to heat build-up in body, accompanied by fluid loss Nutrition & Diet Therapy (7th Edition) • 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 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) Nutrition & Diet Therapy (7th Edition) 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 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 Nutrition & Diet Therapy (7th Edition) Nutrition & Diet Therapy (7th Edition) 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 1st priority to prevent heat stroke • Carbohydrates also needed to supplement limited glycogen stores Nutrition & Diet Therapy (7th 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 Nutrition & Diet Therapy (7th 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 Nutrition & Diet Therapy (7th Edition) Diets for Physically Active People Nutrition & Diet Therapy (7th 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 Nutrition & Diet Therapy (7th 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 30005000 kcalories/day – Strategy is to make sure fruit & vegetable choices are as nutrient- & energy-dense as possible Nutrition & Diet Therapy (7th Edition) Nutrition & Diet Therapy (7th Edition) 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 (300800 kcalories) • Easy to digest • Contain fluids Nutrition & Diet Therapy (7th Edition) – High-carbohydrate liquid meal ideas • Apple juice, frozen banana & cinnamon • Papaya juice, frozen strawberries & mint • Fat-free milk, frozen banana & vanilla Nutrition & Diet Therapy (7th Edition) Nutrition in Practice— Supplements & Ergogenic Aids Nutrition & Diet Therapy (7th 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 Nutrition & Diet Therapy (7th 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 Nutrition & Diet Therapy (7th 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 Nutrition & Diet Therapy (7th 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 Nutrition & Diet Therapy (7th Edition) • DHEA & androstenedione – Alternatives to anabolic steroids – Short-term side effects • • • • Oily skin, acne Body hair growth Liver enlargement Aggressive behavior – Long-term effects unknown Nutrition & Diet Therapy (7th Edition) Nutrition & Diet Therapy (7th Edition) Nutrition & Diet Therapy (7th Edition)