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Chapter 11. Nutrition, Physical Activity, and Fitness. Ask Yourself. True or False? Regular exercise can help people increase their lean body mass and reduce their fat tissue. Less than 25% of U.S. adults exercise adequately.
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Chapter 11 Nutrition, Physical Activity, and Fitness
Ask Yourself True or False? Regular exercise can help people increase their lean body mass and reduce their fat tissue. Less than 25% of U.S. adults exercise adequately. People who fail to exercise regularly are more likely to fall prey to degenerative diseases such as heart disease, osteoporosis, and diabetes. Essentially, to be fit means to be at desirable weight and to have strong muscles. People should never push themselves to exercise longer or harder than they can easily manage to do.
Of all the components of fitness, cardiovascular endurance has the most impact on health and longevity. If you run out of breath, it is a sign that your heart and lungs are not strong enough to perform the desired tasks. When a muscular athlete stops exercising, much of his or her muscle tissue turns to fat. The use of steroid hormones can cause a disfiguring disease. Athletes can lose 2 or more quarts of fluid during every hour of heavy exercise and must rehydrate before, during, and after exercising. Ask Yourself
Lifetime Fitness • Being fit is more than being free of disease; it is feeling full of vitality and enthusiasm for life. • Fitness: The body’s ability to meet physical demands, composed of four components: • Strength • Flexibility • Muscle endurance • Cardiovascular endurance Fitness, like good nutrition, is an essential component of good health.
Lifetime Fitness The Physical Activity Guidelines for Americans report that health benefits occur with at least 2 hours and 30 minutes a week of moderate-intensity physical activity, such as brisk walking, or any one of numerous others Additional benefits occur with more Can benefit with periods as short as 10 minutes. Alternatively, a minimum of 1 hour and 15 minutes a week of vigorous-intensity aerobic physical activity by doing activities like jogging, aerobic dancing, and jumping rope.
Lifetime Fitness The new guidelines stress the value of moderate activity and suggest that the total amount of activity is more important than the manner in which it is carried out. For total fitness include aerobic activity, strength training, and stretching. Fitness builds slowly—increase gradually. Establish a regular pattern of activity and then aim to increase over time.
Benefits of Physical Activity Increased self-confidence Easier weight control More energy Less stress and anxiety Improved sleep Enhanced immunity Lowered risk of heart disease Lowered risk of certain cancers Stronger bones Lowered risk of diabetes Lowered risk of high blood pressure Increased quality of life Increased independence in life’s later years
Components of Fitness Physical Conditioning A planned program of exercise directed toward improving the function of a particular body system. Overload Placing regular, physical demand on the body and forcing the body to do more will cause it to adapt and function more efficiently. A principle of training is that for a body system to improve, its workload must be increased by increments over time.
Components of Fitness Physical Conditioning • Applying overload to increase strength and size: • Increase frequency (more often) • Increase intensity (more strenuous) • Increase time (exercise longer) • Hypertrophy: An increase in size in response to use. • Atrophy: A decrease in size in response to disuse.
Components of Fitness For Fitness, Remember the FIT Principle • F—frequency:number of exercise sessions per week; at least 3-5 sessions per week are recommended. • I—intensity:how hard you exercise; it is recommended that you exercise at 55%-90% percent of your maximum heart rate per minute, known as your target heart rate. • T—time:duration or length of time that you exercise with your heart rate elevated into your target heart rate zone (the minimum amount is thought to be 20-30 min per session).
Components of Fitness 1. Strength: The ability of muscles to work against resistance. • Purpose of strength training: • Build well-toned muscles to help accomplish work. • Strong muscles, tendons, and ligaments help to prevent injury both at work and play. • Helps with weight loss by increasing lean muscle mass, thereby increasing metabolic rate.
2. Flexibility:the ability to bend or extend without injury; flexibility depends on the elasticity of the muscles, tendons, and ligaments and on the condition of the joints. A flexible body can move as it was designed and will bend rather than tear or break in response to stress. Static stretches:stretches that lengthen tissues without injury; characterized by long-lasting, painless, pleasurable stretches. After a light warm-up, stretch muscles that will be used in your main activity. Stretch at the end of your activity to gradually slow down the activity and lengthen the muscles. Components of Fitness
Components of Fitness 3. Endurance: The ability to sustain an effort for a long time. Two types are: • Muscle endurance: • The ability of a muscle to contract repeatedly within a given time without becoming exhausted. • Cardiovascular endurance: • The ability of the cardiovascular system to sustain effort over a period of time.
Activities to develop cardiovascular fitness: • Aerobic dancing • Bench stepping • Bicycling • Cross-country skiing • Fast walking • Jogging • Roller blading • Roller skating • Rope jumping • Rowing • Running • Speed skating • Stair climbing • Swimming • Treadmill walking or running
Nutrition & Fitness: Forever Young Yesterday’s Genes, Today’s Lifestyle Nearly all of your biochemistry and physiology was fine-tuned to conditions of life that existed earlier than 10,000 years ago. What we eat has changed more in the last 40 years than in the previous 40,000 years.
Nutrition & Fitness: Forever Young Cross Section Comparisons of an Active Young Woman and a Sedentary Woman in Her Late 60s.
Nutrition & Fitness: Forever Young Choose Your Weapons against the life-threatening diseases associated with sedentary aging. • Include 60 minutes of moderate-intensity exercise on most days of the week. • Include resistance exercise to average three days per week.
Energy for Exercise Aerobic and Anaerobic Metabolism • Your body runs on water, oxygen, and food—primarily carbohydrate and fat. • The chemical reactions that use these substances to make energy are called metabolism. • Your body has two interrelated energy-producing systems: • Aerobic:requiring oxygen. • Anaerobic:not requiring oxygen.
Energy for Exercise Aerobic and Anaerobic Metabolism • At rest, muscles burn mostly fat and some carbohydrates for energy. • During exercise, energy use depends on the interplay between fuel and oxygen availability. • During moderate exercise (aerobic activity), your circulatory system has no trouble keeping up with the oxygen demand. The body is able to use both fat and carbohydrate for energy. • When muscle exertion outstrips the oxygen supply, the anaerobic pathway supplies energy. • This anaerobic pathway can only burn carbohydrate for fuel and produces lactic acid.
Energy for Exercise Aerobic and Anaerobic Metabolism • The aerobic and anaerobic metabolic pathways complement and support each other in an effort to supply energy to the body. • Carbohydrate is absolutely essential for exercise. The muscles cannot perform without it. • Aerobic exercise allows muscles to burn fat and extract energy from carbohydrate more efficiently in the presence of oxygen. This conserves the body’s limited store of carbohydrate.
CO2 O2 CO2 O2 CO2 O2 5. The lungs remove carbon dioxide, making the blood ready to be reloaded with oxygen. Air O2 Gas exchange in lungs 1. The lungs deliver oxygen to the blood. CO2 4. The blood carries the carbon dioxide back to the lungs. CO2 Circula- tory system O2 2. The circulatory system carries the oxygenated blood around the body. CO2 Metabolism in muscle 3. The muscles and other tissues remove oxygen from the blood and release carbon dioxide into it.
Energy for Exercise Aerobic Exercise—Exercise for the Heart • This type of exercise causes your heart to pump oxygen-rich blood at a faster pace. • This increased demand makes the heart stronger and increases its endurance. Cardiovascular conditioning or training effect: The effect of regular exercise on the cardiovascular system—including improvements in heart, lung, muscle function and increased blood volume.
Energy for Exercise Target heart rate: • The heartbeat rate that will achieve a cardiovascular conditioning effect for a given person—fast enough to push the heart but not so fast as to strain it. • To make gains in cardiovascular conditioning, you must elevate your heart rate (pulse). Lightly press your middle & index fingers on the radial artery as shown here
To calculate your target heart rate, take the following steps: • Estimate your maximum heart rate (MHR). Subtract your age from 220. Thisprovides an estimate of the absolute maximum heart rate possible for a person your age. 2. Determine your target heart rate range. Multiply your MHR by 55 percent and 90 percent to find your upper and lower limits. (see margin example on page 346) • When you can work out at your target heart rate for 20 to 60 minutes, you know that you have arrived at your cardiovascular fitness goal.
Use It and Lose It! Make exercise a habit. Choose an activity you enjoy. • Tips for Sustaining an Exercise Program: • First, check with your physician. • Find an exercise buddy • Set realistic goals • Experiment to find the right time of day for you • Don’t overdo it! • Don’t focus on weight loss • Focus on energy level and how much better you • feel when your clothes start to fit
Fuels for Exercise Your energy-producing pathways require oxygen and two muscle fuels—glucose and fatty acids. Your muscles and liver (to some extent) supply carbohydrate. The fatty acids come mostly from the fat inside the muscles but partly from the body’s fat stores.
Fuels for Exercise Glucose Use During Exercise Glucose comes from carbohydrate-rich foods. Your body stores glucose in your liver and muscles as glycogen. During exercise, the body supplies glucose to the muscles from the stores of glycogen in the liver and in the muscles themselves. The longer the exercise lasts or the more intense the exercise, more glucose will be used.
Fuels for Exercise Anaerobic exercse: Glucose is the principle energy source for high intensity exercise People who participate in endurance events know how to build up reserves of muscle glycogen so they don’t “hit the wall”
Fuels for Exercise For most people, fat isn’t used much as a fuel for exercise until you’ve been working out aerobically for at least 20 min, and it is not used as a primary fuel until after 2 hours. Fuel use and duration/intensity of exercise
Fuels for Exercise • When you exercise, the fat your muscles burn comes from the fatty deposits all over the body. • A person who is of desirable body weight may store 25 to 30 pounds of body fat but only about 1 pound of carbohydrate. • Although your supply of fat is almost unlimited, the ability of your muscles to use fat for energy is not.
A high-carbohydrate diet can increase an athlete’s endurance. The effect of diet on physical endurance
Protein Needs for Fitness Muscles grow in response to work, not to eating protein
Fluid Needs and Exercise • Water in your blood—known as plasma volume, or just plasma—continually circulates throughout your body. • Plasma picks up heat generated by muscles and transports it to skin. • Heat is expelled by the body primarily by evaporation of sweat. • As the body heats up due to the energy released during exercise, it loses water by sweating.
Fluid Needs and Exercise • The amount of fluid loss through sweating is related to intensity and duration of exercise. • If fluid is not replaced, the plasma volume will decrease. • The body will pull water from muscles and organs. • Cramping may occur. • Premature fatigue and a decline in performance may occur. • Ignoring body fluid needs can hinder performance and increase risk of heat-related injury.
Fluid Needs and Exercise Fluid Replacement Drinks A properly balanced sports drink consumed during endurance events of at least 60 minutes may do the following: • Enhance energy status • Enhance endurance • Help maintain plasma volume levels
Fluid Needs and Exercise Fluid Replacement Drinks • Sports drinks are designed to enhance the body’s use of carbohydrate and water. • The carbohydrate in a sports beverage serves three purposes during exercise: • Becomes an energy source for working muscles. • Helps maintain blood glucose at an optimum level. • Helps increase the rate of water absorption from the small intestine, helping maintain plasma volume.
Fluid Needs and Exercise • The choice between water and a sports drink is primarily a matter of personal taste and desired performance abilities. • Sports drinks may provide too many calories for those who are exercising to lose weight. • Sodium content may be a concern for many individuals, too. Plan to drink fluids before, during, & after exercise
Signs of dehydration and heat stroke: Heat Stroke: an acute and dangerous reaction to heat buildup in the body, requiring emergency medical attention; also called sun stroke. • Very high body temperature • 104°Fahrenheit or higher • Hot, dry, red skin • Sudden cessation of sweating • Deep breathing and fast pulse • Blurred vision • Confusion, delirium, hallucinations, convulsions • Loss of consciousness
To prevent heat stroke: • Drink plenty of fluid • before, during, and after physical activity; • avoid over exercising in hot weather • and stop exercising at any sign of heat exhaustion!
Signs of heat exhaustion include: Cool, clammy, pale skin Dizziness Dry mouth Fatigue/weakness Headache Muscle cramps Nausea Sweating Weak and rapid pulse
Vitamins & Minerals for Exercise Vitamins Minerals Iron is a core component of the body’s oxygen taxi service: hemoglobin and myoglobin. A lack of oxygen compromises the muscles’ ability to perform. Sports anemia: A temporary condition of low blood hemoglobin level, associated with the early stage of athletic training. • The links and regulators of energy-producing and muscle-building pathways. • Without them, your muscles’ ability to convert food energy to body energy is hindered and muscle protein formation is slowed. • The B vitamins are of special interest to athletes because they govern the energy-producing reactions of metabolism.
Food for Fitness • The best nutrition prescription for peak performance is a well-balanced diet. • Two critical nutrition periods for the athlete are the training diet and precompetition diet. • An eating plan should supply • 60% of calories from complex carbohydrate • 15% of calories from protein • 25% of calories from fat • Will enable both athletes and fitness enthusiasts to supply muscles with a proper fuel mix and maintain health.
