Understanding Nutrition

1. Understanding Nutrition Chapter 14 Fitness: Physical Activity, Nutrients, and Body Adaptation By A. Fellah, Ph.D.

2. Physical Activity and Fitness Is this person physically fit? You can’t tell by looking. Fitness involves more than muscles. It includes a person’s ability to sustain physical activity over time.

3. Fitness • Fitness is the characteristics that enable the body to perform physical activity. • The ability to meet routine physical demands with enough reserve energy to rise to a physical challenge. • The body’s ability to withstand stress of all kinds. • Sedentary: physically inactive (setting down a lot). • Fosters the development of several chronic diseases. • Body composition: the proportions of muscle, bone, fat, and other tissue that make up a person’s total body weight.

4. Benefits of Fitness • Activities that promote fitness are themselves enjoyable: • Restful sleep. Rest and sleep occur naturally after periods of physical activity. During rest, the body repairs injuries, disposes of wastes, and builds new physical structures. • Nutritional health. Physical activity spends energy and thus allows people to eat more food. • Optimal body composition. A balanced program of physical activity limits body fat and maintains lean tissue. • Optimal bone density. Weight-bearing physical activity builds bone strength and protects against osteoporosis. • Resistance to colds and other infectious diseases. Fitness enhances immunity.

5. Reducing Risks of Certain Diseases Benefits of regular physical activity.

6. Benefits of Fitness • Low risks of some types of cancers. Lifelong physical activity may help to protect against colon cancer, and breast cancer. • Strong circulation and lung function. challenges the heart and lungs slows the aging of the circulatory system. • Low risk of cardiovascular disease. lowers blood pressure, slows resting pulse rate, and lowers blood cholesterol, thus reducing the risks of heart attack and strokes. • Low risk of type 2 diabetes. normalizes glucose tolerance, especially via the secretion of insulin. • Reduced risk of gallbladder disease in women. reduces women's risk of gallbladder disease-perhaps by facilitating weight control and lowering blood lipid levels.

7. Benefits of Fitness • Low incidence and severity of anxiety and depression. Active people deal with better with psychological stress. • Strong self-image. The sense of achievement that comes from meeting physical challenges promotes self-confidence. • Long life and high quality of life in the later years. Active people have a lower mortality rate than sedentary people. • As a person becomes physically fit, the health of the entire body improves.

8. Checking Heart Rate To find out if you’re exercising at the right level, take your pulse during a break or right after you finish exercising.

9. Components of Fitness • Flexibility:the capacity of the joints to move through a full range of motion; the ability to bend and recover without injury. • Muscle strength: the ability of muscles to work against resistance. • Muscle endurance: the ability of a muscle to contract repeatedly without becoming exhausted. • Cardiorespiratory endurance: the ability to perform dynamic exercise of moderate-to-high intensity for prolonged periods. • Conditioning: the physical effect of training; improved flexibility, strength, and endurance. • Training: practicing an activity regularly, which leads to conditioning. (Training is what you do; conditioning is what you get.)

10. Components of Fitness • Progressive overload principle: the training principle that a body system, in order to improve, must be worked at frequencies, durations, or intensities that gradually increase physical demands. • Frequency: the number of occurrences per unit of time (for example, the number of activity sessions per week). • Intensity: the degree of exertion while exercising (the amount of weight lifted or the speed of running). • Duration: length of time (the time spent in each activity session).

11. People’s bodies are shaped by the activities they perform.

12. Warming Up and Cooling Down It’s always a good idea to S–T–R–E–T–C–H before exercise.

13. Conditioning by Training • Warm-up:5 to 10 minutes of light activity, such as easy jogging or cycling, prior to a workout to prepare the body for more vigorous activity. • Cool-down: 5 to 10 minutes of light activity, such as walking or stretching, following a vigorous workout to return the body's core gradually to near-normal temperature. • Moderate exercise: activity that can be sustained comfortably for 60 minutes or so. • Hypertrophy: of muscles, growing larger; an increase in size in response to use. • Atrophy: of muscles, becoming smaller; a decrease in size because of disuse, undernutrition, or wasting diseases.

14. Percentage of Adults Who Exercise The percentage of adults aged 18 and over who engaged in physical activity five or more times per week in 1990.

15. Conditioning by Training • Weight training (also called resistance training): • The use of free weights or weight machines to provide resistance for developing muscle strength and endurance. • A person's own body weight may also be used to provide resistance as when a person does push-ups, pull-ups, or abdominal crunches.

16. Americans and Exercise The proportion of people aged six and older who engage in no leisure-time physical activity.

17. Cardiorespiratory Endurance • VCLmax: the maximum rate of oxygen consumption by an individual at sea level. • Cardiorespiratory conditioning: improvements in heart and lung function and increased blood volume, brought about by aerobic training. • Cardiac output: the volume of blood discharged by the heart each minute; determined by multiplying the stroke volume by the heart rate. • The stroke volume is the amount of oxygenated blood the heart ejects toward the tissues at each beat. • Cardiac output (volume/minute) = stroke volume (volume/beat) x heart rate (beats/minute).

18. Physical Activity Guidelines

19. Delivery of O2 by Heart and Lungs to the Muscles • The more fit a muscle is, the more oxygen it draws from the blood. • This oxygen comes from the lungs, so the person with more fit muscles extracts oxygen from inhaled air more efficiently than a person with less fit muscles. • The cardiovascular system responds to increased demand for oxygen by building up its capacity to deliver oxygen. • Researchers can measure cardiovascular fitness by measuring the amount of oxygen a person consumes per minute while working out. This measure of fitness is called VO2 max.

20. Delivery of O2 by Heart and Lungs to the Muscles

21. Determining VO2 Max • This man is running on a treadmill. His nose is plugged, so he must breathe through a tube in his mouth. • The tube is attached to an apparatus that measures the total amount of air breathed in and out, and the difference between the amount of oxygen inhaled and exhaled. • Every few minutes the slope or speed of the treadmill is increased, making the exercise more intense. • The amount of oxygen he utilizes at the point when his exercise intensity can go no higher is considered “maximal oxygen consumption,” or VO2 max.

22. Energy Systems, Fuels, and Nutrients to Support Activity • ATP: in the muscle, ATP provides the chemical driving force for contraction. When ATP is split, its energy is released and muscle cells channel some of the energy into mechanical movement. • CP, creatine phosphate: a high-energy compound in muscle cells that acts as a reservoir of energy that can maintain a steady supply of ATP, CP provides the energy for short bursts of activity. • During rest: ATP + creatine → CP • During activity: CP → ATP + creatine

23. Glucose Use during Physical Activity • Diet Affects Glycogen Storage and Use: • The body constantly uses and replenishes its glycogen. • To fill glycogen stores, eat plenty of carbohydrate-rich food. • Intensity of Activity Affects Glycogen Use: • Intense activity: exercises at a rate that exceeds the capacity of the heart and lungs to supply oxygen to the muscle. • The glucose is the source of energy (anaerobic activity). • Moderate activity: the individual breaths easily, the heart beats steadily (aerobic activity). • Energy derived from both glucose and fatty acids.

24. The effect of diet on physical endurance A high-carbohydrate diet can triple an athlete’s endurance

25. Exercise Intensity and Heart Rate Schematic representation showing the proportionate use of sources of energy for physical activities of various intensities. Most activities are fueled by both fat and glucose.

26. Glucose and Fatty Acids in Their Energy-Releasing Pathways

27. Glucose as an aerobic fuel

28. Recycling of Glucose Glucose use during physical activity.

29. Glucose Depletion • To maximize glucose supply, endurance athlete: • • Eat a high-carbohydrate diet regularly. • (approximately 8 grams of carbohydrate per kilogram of body weight or about 70 percent of energy intake) • • Take glucose periodically during activity that lasts for an hour or more. (usually in sports drinks, diluted fruit juice, or other beverages). • • Eat carbohydrate-rich foods following activity. • (approximately 60 grams of carbohydrate) • • Train the muscles to store as much glycogen as possible.

30. Glycogen Depletion in Cyclists.

31. Fat Use during Physical Activity • Duration of Activity Affects Fat Use • When blood fatty acids level fall, the hormone epinephrine is released and the fat cells begin breaking down stored triglycerides and librating fatty acids into the blood. • After 20 minutes of activities, the blood fatty acid concentration surpasses the normal resting level. • Intensity of Activity: • As intensity increases, fat makes less contribution. • Fat can be broken down for energy only by aerobic metabolism. • This process requires oxygen.

32. Training Affects Fat Use: • To burn more fat , train aerobically. • Training stimulate the muscle cells to make more and larger mitochondria, the cellular structures that conduct aerobic metabolism. • To lose weight, increase your physical activity enough to spend more energy than you consume from foods. • Select an activity and an intensity level that are challenging, but not overwhelming.

33. Fat as an aerobic fuel

34. Protein Use during Physical Activity • Protein Used in Muscle Building: • Synthesis of protein is suppressed during activity and for several hours. • Then it accelerates beyond normal resting levels. • The physical work of muscle cell acts as a signal to its DNA and RNA to produce proteins needed for that work. • During active muscle –building phases of training, an athlete may add between ¼ -1 ounce (7-28 g) of body protein to existing muscle mass each day. • Protein Used as Fuel: • Muscles speed up their use of amino acids for energy during physical activity. • Protein contributes at most ~10% of total fuel used.

35. Diet Affects Protein Use during Activity; • To conserve protein, eat a diet adequate in energy and rich in carbohydrate. • Intensity and Duration of Activity Affect Protein Use during Activity • Intensity and long duration, may deplete glycogen stores. • Training Affects Protein Use • The higher the degree of training, the less protein a person uses. • Protein Recommendations for Active People • All athletes in training should attend to protein needs, but should back up the protein that they wish to retain in muscle.

36. Vitamins and Minerals to Support Activity • Supplements: • Don’t enhance the performance of well-performance. • Active people who eat enough nutrient-dense foods to meet energy needs also meets their vitamin & minerals needs. • Iron: • Physically active young women are prone to iron deficiency. • Physical activity can affect iron status in: • Iron losses in sweat, destruction of red blood cells, poor iron absorption, and high demands of muscle myoglobin. • Sports anemia: • A transient condition of low hemoglobin in the blood, associated with the early stages of sports training

37. Fluids and Electrolytes to Support Activity • During physical activity, water losses from sweating and breathing are significant, and dehydration becomes threat. • First symptom of dehydration is fatigue: • 1-2% water loss of body weight can reduce a person’s capacity to do the work. • 7% water loss, a person is likely to collapse. • Hyperthermia: an above-normal body temperature. • Body heat builds up and triggers maximum sweating, bur without sweat evaporation, little cooling takes place. • Heat stroke: a dangerous accumulation of body heat with accompanying loss of body fluid. • Symptoms: headache, nausea, dizziness, clumsiness, stumbling

38. Active people need extra fluid, even in cold weather

39. Hydration Schedule Hydration schedule for physical activity.

40. An Athlete’s Meal Selections: 1 of 4 Breakfast

41. An Athlete’s Meal Selections: 2 of 4

42. An Athlete’s Meal Selections: 3 of 4

43. An Athlete’s Meal Selections: 4 of 4

44. Summary • Regular physical activity benefits a person physically, psychologically and socially and provides many health benefits. • Flexibility, strength, muscle endurance and cardiorespiratory endurance are components of fitness. • Training conditions the human body to be more fit. • Muscle cells adapt in size and work capacity in response to demands. • Cardiovascular conditioning A improves heart and lung functioning to bring more oxygen to the cells. • Both strength and endurance activities need to be included in a balanced fitness program.

45. Summary • A mixture of fuels is required for physical activity. • During intense activity, muscles use glucose primarily. • Low to moderate activity uses more fat. • Protein is needed to build and maintain lean body tissue. • Vitamins and minerals must be provided to support energy metabolism and tissue building. • Water helps to distribute the fuels and eliminate waste. • Water is especially important during training and competition.

46. Summary • The most common problems of female athletes include eating disorders, iron deficiency, amenorrhea and osteoporosis. • A suggested diet for physically active people must provide ample fluids, and a variety of nutrient-dense foods in quantities that meet energy needs. • A healthful diet surpasses the need for pills and powders to enhance athletic performance. • Highlight 14 addresses the issues of supplements as ergogenic aids.