Nutrition and Physical Activity: Keys to Good Health

1. 14 Nutrition and Physical Activity: Keys to Good Health

2. Physical Activity vs. Fitness • Physical activity: any movement produced by muscles that increases energy expenditure • Leisure-time physical activity: any activity unrelated to a person’s occupation • Competitive sports • Recreational: hiking, walking, biking • Exercise: purposeful, planned, and structured

3. Physical Activity vs. Fitness • Physical fitness: state of being from interaction between nutrition and physical activity • Physical fitness includes cardiorespiratory fitness, musculoskeletal fitness, flexibility • Body composition is the amount of bone, muscle, and fat tissue in the body

5. Benefits of Physical Activity • Reduces the risk of heart disease, stroke, high blood pressure • Reduces the risk for obesity and type 2 diabetes • Reduces the risk for osteoporosis • May reduce the risk of colon cancer • Improves sleep patterns, immune function • Reduces anxiety and mental stress

6. Benefits of Physical Activity • Despite the clear benefits of regular physical activity: • Most Americans are physically inactive • 16% of U.S. adults experience no leisure-time physical activity • Less than 30% of high school students participate in daily physical education

8. Sound Fitness Program • Meets personal goals • Is varied, consistent, and fun • Physical Activity Pyramid recommends the type and amount of activity • Includes aerobic-type activities and resistance training • Appropriately overloads the body

10. The FIT Principle • Frequency—number of activity sessions per week • Intensity—amount of effort expended or how difficult the activity is to perform • Estimating maximal heart rate • Borg Scale of Perceived Exertion: rating of perceived exertion (or RPE) • Time of activity—how long session lasts

14. Warm-up and Cool-down Period • To properly prepare for and recover from an exercise session • Warm-up increases blood flow and temperature, and prepares a person for the activity (5 to 10 minutes) • Cool-down helps to prevent injuries and may reduce muscle soreness

15. Fuel for Physical Activity • Adenosine triphosphate (ATP): the energy-carrying molecule in the body • ATP must be generated continuously since muscles store only enough ATP for 1–3 seconds of activity

17. Fuel for Physical Activity • After depleting ATP stores, muscles turn to other sources: • Creatine phosphate (CP) stores some energy that can be used to make ATP • CP stores enough energy for 3−15 seconds of maximal physical effort

20. Fuel for Physical Activity • After creatine phosphate, glucose is the next source of energy for ATP production • Glucose provides ATP through glycolysis • Glucose source during exercise: muscleglycogen and blood glucose • Glycogen stores are limited

21. Fuel for Physical Activity • Primary glycolysis end product: pyruvate • With limited oxygen, pyruvate is converted to lactic acid, a by-product of intense activity • Excess lactic acid goes back to the liver to be converted back into glucose

23. Fuel for Physical Activity • Glucose metabolism • Anaerobic breakdown of glucose yields 2 ATP molecules • Aerobic breakdown of glucose yields 36–38 molecules of ATP

24. Fuel for Physical Activity • Triglycerides (fats) can be metabolized to generate ATP • For low-intensity exercise • For exercise of long duration (marathons) • Abundant energy source, even in lean people • 2x more energy per gram as carbohydrates • Slow in breaking down • Primary energy source during rest, sitting, and standing in place; also endurance events

25. Fuel for Physical Activity • Carbohydrates and fats can both be used as energy sources for ATP production • Carbohydrates are mostly used for high-intensity activity • Fats are used for low-intensity exercise • Proteins (amino acids) are not used as a fuel source for exercise

27. Energy Needs • Vigorous exercise increases energy needs • Higher for athletes • Different energy needs for males, females • Needs depend on body size • Needs depend on the type of physical activity

29. Carbohydrate Needs • Athletes should consume carbohydrate intakes: 45−65% of total energy • Following exercise: consuming carbs with protein enhances muscle protein synthesis • Optimize glycogen storage: first 4−6 hours of recovery • Complex, less-processed carbohydrates: whole grains, fruits, and vegetables supply fiber, vitamins, and minerals

32. Carbohydrate (Glycogen) Loading • Alter exercise duration and carbohydrate intake to maximize muscle glycogen • Does not always improve performance • Side effects: gastrointestinal distress; feeling heavy, bloated, and sluggish

35. Training Effects on Fat Metabolism • Increased number and activity of enzymes involved in fat metabolism • Improved ability of muscles to store fat • Improved ability to extract fat from the blood for use during exercise • Spares carbohydrate for prolonged, intense training or competition

36. Protein Needs • Increased protein needs for competitive, endurance, and resistance athletes • Individuals who are already trained need less protein than those who are initiating training • Recreational endurance athletes’ protein need is equal to or slightly higher than the RDA • Individuals with very low energy intakes • Vegetarians consuming low-protein foods • Young athletes who are growing

37. Protein Needs • High-protein, low-carbohydrate diet marketed for athletes: NOT recommended • Too low in energy and carbohydrates to support training and performance • People of all fitness levels can consume enough protein foods without using supplements or specially formulated foods

39. Fluid Needs • Functions of water • Lubricant that bathes tissues and cells • Transportation of nutrients, hormones, waste products • Component of chemical reactions • Part of body tissues (proteins and glycogen) • Temperature regulation: evaporative cooling

40. Water Balance • Heat syncope: dizziness • Heat cramps: muscle spasms • Heat exhaustion and heatstroke occur on a continuum; symptoms include: • Excessive sweating, weakness, nausea, dizziness, headache, difficulty concentrating

42. Proper Fluid Replacement • Drink fluids before, during, and after exercise • Thirst mechanism not reliable • Drink enough to maintain body weight

44. Vitamins and Minerals • Requirements for some vitamins and minerals may be altered in athletes • B-vitamins • Calcium and the female athlete triad • Iron • Iron supplementation may be required under proper medical supervision • Most nutrient needs can be met with a healthy diet

45. Ergonomic Aids • Substances used to improve exercise and athletic performance • Many are not effective • Some have harmful side effects • Most are very expensive • Many have not been adequately studied

46. Ergonomic Aids • Anabolic products promoted as muscle and strength enhancers • Anabolic steroids • Androstenedione (“andro”) and Dehydroepiandrosterone (DHEA) • Gamma-hydroxybutyric acid (GHB) • Creatine

47. Ergonomic Aids • Ergonomic aids used to increase energy levels and optimize fuel use include: • Caffeine • Ephedrine • Carnitine • Chromium • Ribose