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

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 2

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 3

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 5

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 6

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 8

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 10

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 14

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 15

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 17

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: muscle glycogen and blood glucose Glycogen stores are limited 20

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 21

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

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 24

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 25

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 27

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 29

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 32

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 35

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 36

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 37

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 39

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 40

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

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 44

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 45

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

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