Chapter 16 nutrition and fitness
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Chapter 16: Nutrition and Fitness. What Is Physical Fitness and Why Is It Important?. Physical fitness is good health or physical condition as a result of exercise and proper nutrition Physical activity is body movement that expends energy (kilocalories)

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Chapter 16: Nutrition and Fitness

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Chapter 16 nutrition and fitness

Chapter 16: Nutrition and Fitness


What is physical fitness and why is it important

What Is Physical Fitness and Why Is It Important?

  • Physical fitness is good health or physical condition as a result of exercise and proper nutrition

  • Physical activity is body movement that expends energy (kilocalories)

  • Exercise is formalized training or structured physical activity


What is physical fitness and why is it important1

What Is Physical Fitness and Why Is It Important?

  • Five basic components of physical fitness which must be considered to achieve optimal fitness

    • Cardiorespiratory endurance – ability to sustain cardiorespiratory exercise for an extended period of time

    • Muscular strength – ability to produce force for a brief period of time

    • Muscular endurance – ability to exert force over a long period of time without fatigue

    • Flexibility – range of motion around a joint, improved with stretching

    • Body composition – the proportion of muscle, fat, water, and other tissues in the body


What does a successful physical fitness program look like

What Does a Successful Physical Fitness Program Look Like?

  • Incorporates activities based on the five components of fitness

  • Tailored to meet needs of individual


Cardiorespiratory exercise

Cardiorespiratory Exercise

  • Can improve cardiorespiratory endurance and body composition

  • Cardiorespiratory fitness is measured by VO2max, the maximum amount of oxygen muscles can consume during exercise

    • Gradual increases in exercise intensity will help increase VO2max

  • Cardiorespiratory exercise also helps to maintain a healthy body weight, improves body composition, reduces stress, and reduces risk of heart disease


Strength training and stretching

Strength Training and Stretching

  • Improve muscle strength, muscle endurance, and body composition

    • A low number of repetitions using heavy weights will increase muscle strength

    • To increase muscle endurance, perform a high number of repetitions with lighter weights

    • Rest between sets of exercises and between workouts to avoid overworking muscles and decrease risk of injury

  • Stretching can improve flexibility; reduce muscle soreness and risk of injury; and improve balance, posture, and circulation


What does a successful physical fitness program look like1

What Does a Successful Physical Fitness Program Look Like?

  • The progressive overload principle can help improve fitness over time

    • A gradual increase in exercise demands from modifications to the frequency, intensity, time, or type of exercise

    • Prevents a plateau of fitness level due to the body adapting to an exercise regimen


Quick review

Quick Review

  • A successful fitness program incorporates the five components of fitness

  • Cardiorespiratory exercise improves cardiorespiratory endurance and body composition

  • Strength training improves muscle strength and endurance

  • Stretching increases flexibility and reduces risk of injury

  • An effective fitness program can be designed using the FITT principle

  • The 2008 Physical Activity Guidelines provide recommendations for duration and intensity of exercise based on individual health goals such as weight management or improved physical fitness

  • Applying the progressive overload principle helps individuals achieve optimal fitness levels


How are carbohydrate fat and protein used during exercise

How Are Carbohydrate, Fat, and Protein Used During Exercise?

  • Most energy production during cardiorespiratory exercise is aerobic

  • Anaerobic energy is generated for quick, intense activities that require strength, agility and speed, or a sudden burst of energy.


How are carbohydrate fat and protein used during exercise1

How Are Carbohydrate, Fat, and Protein Used During Exercise?

  • During the first few minutes of physical activity, the body relies heavily on anaerobic energy production from ATP and creatine phosphate (PCr)

  • PCr stored in muscles is depleted after 10 seconds of maximum intensity exercise; stored ATP can only support a few seconds of intense exercise

  • Once stores are depleted, the body relies on aerobic production of ATP


Anaerobic energy metabolism

Anaerobic Energy Metabolism

Figure 16.2


Carbohydrate and exercise

Carbohydrate and Exercise

  • Carbohydrate is the primary energy source during high-intensity exercise

    • Obtained from blood glucose and from stored glycogen in muscles and liver

    • ~2,000 kcals of energy as carbohydrate is available; enough to perform 2 hours of moderate-intensity exercise

    • As intensity of exercise increases, lactate is formed and can begin to accumulate in muscle tissue

      • New research suggests it can be an important fuel during exercise

  • Eat simple carbohydrates during and/or immediately after exercise

    • Athletes use carbohydrate loading before competition


Fat and exercise

Fat and Exercise

  • Fat (as fatty acids) is the primary energy source during low- to moderate-intensity exercise

    • Derived from fatty acids stored in muscle tissue and free fatty acids in the blood from adipose stores

    • Use of fat for energy increases throughout the duration of low- to moderate-intensity exercise

    • Endurance training increases muscle fatty acid stores which can increase amount of fat used for energy


Protein and exercise

Protein and Exercise

  • Protein is primarily needed to build and repair muscle

    • Exercise increases cortisol which stimulates protein turnover

    • All active people use small amounts of protein for energy

    • When kilocalorie intake and carbohydrate stores are insufficient, the body relies on protein

    • If protein breakdown exceeds protein synthesis, muscle atrophy can occur

    • Most recreational exercisers can easily meet protein needs (0.8 g/kg) with a balanced diet

      • Endurance athletes and those doing significant resistance/strength training may need more protein


Energy use during various intensities of exercise

Energy Use During Various Intensities of Exercise

Figure 16.3


Food intake and exercise

Food Intake and Exercise

  • The timing of meals affects fitness and athletic performance

    • Important to allow sufficient time for food to digest before exercise

      • Large meals3–4 hours

      • Smaller meals2–3 hours

      • Liquid supplement or small snack30 min–1 hour

    • Food intake is important to maintain blood glucose supply in exercise lasting greater than 1 hour

      • Carbohydrate intake recommended at 15–20 min intervals

      • 30–60 g of carbohydrate should be consumed per hour

    • Food eaten after exercise will affect how the body recovers


Food intake and exercise1

Food Intake and Exercise

  • Optimal foods before exercise

    • 1–4.5 g/kg carbohydrate 1–4 hours prior to exercise

    • Consumption of protein and carbohydrate recommended

    • High-fat foods should be avoided several hours before exercise

  • Optimal foods during exercise

    • Sports drinks, bars, and gels

    • Fructose (fruit sugar) may cause GI distress

    • Consuming carbohydrate and protein improves net protein balance for endurance athletes


Food intake and exercise2

Food Intake and Exercise

  • Optimal foods after exercise

    • Consuming carbohydrate after exercise helps to replenish muscle and liver glycogen. It is most effective 30–45 minutes after exercise.

    • Consuming protein and carbohydrate after exercise increases muscle protein synthesis

      • Low-fat chocolate milk is a low-cost option to provide whey protein and carbohydrate to assist in recovery

    • A high-carbohydrate, moderate-protein, low-fat meal should be consumed within 2 hours


Quick review1

Quick Review

  • Carbohydrate from blood glucose and muscle and liver glycogen are the main source of energy during high-intensity exercise

  • Fat is the main energy source for low- to moderate-intensity exercise

  • Protein promotes muscle growth and repair of muscle breakdown caused by exercise

  • Both the timing of meals and the foods eaten can affect exercise performance and recovery time


Vitamins and minerals in fitness

Vitamins and Minerals in Fitness

  • Intense, prolonged exercise increases production of free radicals

    • Antioxidants such as vitamins E and C protect cells from the damage of free radicals

    • Research has not shown that supplementation above the RDA improves athletic performance or decreases oxidative stress

  • Unless the body is deficient in a nutrient, vitamin and mineral supplements will not improve athletic performance


Vitamins and minerals in fitness1

Vitamins and Minerals in Fitness

  • Certain minerals may be a concern in highly active people

    • Iron

      • Necessary for energy metabolism and oxygen transport

      • Levels may be low due to menstruation in women, intravascular hemolysis, or sports anemia

    • Calcium

      • Lost in sweat, thus losses may be high in athletes

      • Supplementation not recommended unless intake from food and beverage is inadequate to meet the RDA


Quick review2

Quick Review

  • Antioxidants such as vitamins E and C are thought to protect cells from free radical damage though research has not shown that supplementation is beneficial to athletes

  • Certain minerals may be a concern to athletes including calcium and iron

  • Adequate amounts of nutrients can be consumed in foods, so supplementation is usually not necessary

  • Anyone should consult a physician or Registered Dietitian before taking dietary supplements


How does fluid intake affect fitness

How Does Fluid Intake Affect Fitness?

  • Consuming adequate fluid during exercise is essential for preventing dehydration and promoting optimal performance

  • During exercise, the body loses water and electrolytes (sodium, chloride, and potassium) in sweat

    • In hot, humid weather sweat may not evaporate and risk of hyperthermia increases

    • Cold weather, especially if wet, can contribute to hypothermia

    • The body sweats when exercising both in hot and cold weather, so meeting fluid needs is always a concern


How does fluid intake affect fitness1

How Does Fluid Intake Affect Fitness?

  • Fluids are needed before, during, and after exercise

    • Healthy adult women require 9 cups water/day

    • Healthy adult men require 13 cups water/day

    • To determine fluid needs for exercise

      • Weigh yourself before and after exercise

      • Consume 16–24 ounces of fluid for every pound of body weight lost during exercise


How does fluid intake affect fitness2

How Does Fluid Intake Affect Fitness?

  • Sports drinks contain 6–8% carbohydrate and sodium and potassium

    • Most beneficial for exercise lasting longer than 60 minutes

  • Certain beverages are suboptimal for hydration during physical activity

    • Juice and juice drinks

    • Carbonated drinks

    • Alcohol

    • Caffeine


Effects of dehydration on exercise performance

Effects of Dehydration on Exercise Performance

Figure 16.4


How does fluid intake affect fitness3

How Does Fluid Intake Affect Fitness?

  • Consuming too little or too much fluid can be harmful

  • Too little fluid

    • To prevent acute dehydration follow a regimented hydration schedule before, during, and after exercise

    • Chronic dehydration is due to inadequate fluid consumption over a long period of time and may be indicated by very dark urine and infrequent bathroom trips


How does fluid intake affect fitness4

How Does Fluid Intake Affect Fitness?

  • To much fluid

    • Taking in too much water without sufficient electrolytes can dilute the blood and cause hyponatremia

      • Symptoms of hyponatremia include rapid weight gain, nausea, vomiting, swollen hands and feet, headache, dizziness, and confusion


Quick review3

Quick Review

  • Adequate hydration before, during, and after exercise is important to sustain fluid and electrolyte balance and normal body temperature

  • Consuming too little or too much fluid can be harmful and impair performance

  • Water is the preferred beverage for hydration, but sports drinks can be beneficial during moderate- or vigorous-intensity exercise of a longer duration


Can dietary supplements contribute to fitness

Can Dietary Supplements Contribute to Fitness?

  • An ergogenic aid is any substance that is used to improve athletic performance

  • Most commonly used aids include

    • Creatine

    • Caffeine

    • Anabolic steroids

    • Growth hormone

    • Erythropoietin


Creatine

Creatine

  • Improves athletic performance in high-intensity, short-duration activities such as weight training

  • Shown to increase muscle strength and muscle mass

  • No negative effects on blood pressure, kidney, or liver function in healthy people


Caffeine

Caffeine

  • Stimulates the central nervous system and decreases perception of effort

    • May increase metabolism of fatty acids for energy and spare glycogen stores

  • Enhances athletic performance during endurance events

  • NCAA classifies as a banned substance when urine concentrations exceed 15 micrograms per milliliter


Anabolic steroids

Anabolic Steroids

  • Testosterone-based substances that promote muscle strength and development

  • Many negative side effects including

    • Impotence in men

    • Amenorrhea in women

    • Changes in hair growth

    • Extreme mood swings and aggressiveness

  • Use is prohibited by most professional agencies


Growth hormone

Growth Hormone

  • Increases protein synthesis, causing an increase in muscle mass but not strength

    • Could impair performance by reducing power, speed, and endurance

  • Decreases glycogen breakdown and increases the use of fatty acids for energy which can decrease body fat

  • Abuse of growth hormone can lead to development of diabetes, atherosclerosis, hypertension, or acromegaly


Erythropoietin

Erythropoietin

  • Hormone produced by the kidneys that stimulates synthesis of red blood cells

    • Synthetic versions used to increase oxygen carrying capacity of blood

  • Synthetic erythropoietin is a banned substance in most athletic organizations

    • Blood doping (red blood cell reinfusion) is an older method used to increase oxygen-carrying capacity of blood

    • Both blood doping and synthetic erythropoietin increase blood viscosity and could cause stroke or heart attack


Meal replacements

Meal Replacements

  • Sports bars and shakes are not defined as dietary supplements by the FDA

    • Main energy source is carbohydrate with some protein and fat

    • Offer convenience, but are often expensive

    • Should not replace whole, nutritious foods in the diet


Quick review4

Quick Review

  • Dietary supplement and ergogenic aids such as creatine, caffeine, anabolic steroids, growth hormone, erythropoietin and blood doping, may enhance performance, but can have serious side effects

  • Sports bars and shakes are convenient energy sources, but can be costly and should only be included as a minor part of an overall healthy diet


Putting it all together

Putting It All Together

  • Cardiorespiratory endurance, muscle strength, muscle endurance, flexibility, and body composition are the components of fitness

  • Effective conditioning programs can be designed using the FITT and progressive overload principles

  • Both the timing of meals and the foods eaten can affect exercise performance and recovery time

  • Certain vitamins and minerals are a concern to athletes; supplementation is not usually necessary as adequate amounts can generally be consumed in foods

  • Sports drinks may be beneficial for moderate to vigorous activities or endurance sports

  • Dietary supplements and ergogenic aids may enhance performance, but can have negative side effects


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