1. Jamie Pope, Steven Nizielski, and Alison McCook
NUTRITION
for a Changing World
FIRST EDITION
Chapter 16
Nutrition and Fitness
Eating to Win
© 2016 by W. H. Freeman and Company & Scientific American

2. Chapter 16
Objectives
Identify five health-related benefits of regular physical activity
Describe the four components of physical fitness
Identify the components of the anaerobic and aerobic energy systems, and rank these four components according to the rate at which they produce adenosine triphosphate (ATP)
Describe how exercise intensity and duration affect the use of carbohydrates and fat as fuel
Define carbohydrate loading, and describe when the practice may be beneficial
Explain why adequate dietary carbohydrates are necessary for endurance training to be effective
Identify factors that affect fluid needs of athletes, and discuss strategies to optimize hydration during and after exercise

3. Components of Physical Fitness
Physical activity
Exercise

4. Benefits of Exercise Short term Long term Helps people lose body fat
Builds muscle mass
Helps people become physically fit
Long term
Reduces the risk of heart disease, stroke, type 2 diabetes, osteoporosis, and certain cancers
Lowers risk of premature death
Manages stress
Reduces anxiety and depression

6. Types of Exercise

7. Types of Exercise

8. Types of Exercise

9. Types of Exercise

10. Fueling the Body Energy substrates Usable form Carbohydrates Fats
Glucose
Fats
Fatty acids
Usable form
Adenosine triphosphate (ATP)

11. Energy-Producing Systems in the Body

12. Anaerobic Energy Systems
Cytosol
Creatine phosphate
Glycolysis
Pyruvate to lactate

13. Aerobic Energy Systems
Mitochondria
Pyruvate
Fatty acids

14. Exercise Intensity and Energy Systems

15. Exercise Intensity and Fuel Utilization

16. Measures of Exercise Intensity
Maximal oxygen consumption (VO2max)
Estimating maximum heart rate (MHR)
MHR = 208 – (age x 0.7)
Borg Rating of Perceived Exertion Scale

17. Diet for Endurance Exercise
Dietary carbohydrates
Glycogen

18. Carbohydrate Loading Increase glycogen stores
Consume 10 to 12 g/kg body weight/day

19. Daily Carbohydrate Intake
Objective
Carbohydrate Intake
Comments
Moderate Intensity about 1 hour per day
5 – 7 g per kg body weight (b.w.) per day
Moderate to High Intensity 1-3 hours per day
7-10 g per kg b.w. per day
Extreme Intensity 4-6 hours per day
10-12 g per kg b.w. per day
Carbohydrate Loading
Consume for 1-2 days prior to competition while reducing training volume and intensity
Pre-exercise Meals 1-4 hours prior to exercise
1-4 g per kg b.w. at 1-4 hours prior to exercise or competition
When eating 2 hours prior to exercise, consume 2 g per kg b.w.; at 3 hours, 3 g per kg b.w., etc.

20. Fuel During Intense Exercise
Objective
Carbohydrate Intake
Comments
Lasting 1-2 hours
30-60 g per hour
A sports drink should not be more concentrated than an 8% solution (80 g/L, or about 9.5 kcal/oz.) as this will slow gastric emptying when the carbohydrate source provides only glucose.
Lasting hours
60 g per hour
Lasting ≥2.5 hours
Up to 90 g per hour
Must consume a mix of glucose and fructose.
In the past the U.S. Gymnastics team did not eat during practice. They became grumpy and did not perform well about halfway through. When fruit and juice (sources of carbohydrates) were allowed during practice, they performed better. After this was introduced, they won the first gold medal ever awarded to a U.S. Women’s Gymnastics team.

21. Female Athlete Triad Interrelationships among Low-energy intake
Menstrual dysfunction (amenorrhea)
Bone loss (osteoporosis)

22. Body Building Resistance training Adequate, balanced, varied diet
Increases muscle mass and strength
Boosts growth of muscle fibers
Made of protein
Adequate, balanced, varied diet
Meet protein, vitamin, and mineral needs

23. Hydrating the Athlete Fluid losses Water Sports drinks Sweating
Limit to 2% body weight
Dehydration
Water
Hyponatremia
Sports drinks

25. Sports Supplements
Ergogenic aids
Caffeine
Creative monohydrate

26. Physical Fitness: Not Just for Athletes
U.S. Department of Health and Human Services recommends adults participate in
At least 2 hours and 30 minutes of moderate- intensity exercise per week or 75 minutes of high-intensity exercise per week
Muscle strengthening activities
Any exercise is better than none

27. Activity for Health
Moderate exercise for at least 30 minutes a day on most days of the week
Reduces risk of chronic disease
Reduces weight gain

28. Summary
Physical fitness is the ability to perform moderate to vigorous activity without undue fatigue and can be achieved through regular exercise or intentional physical exertion
The four types of exercise recommended by the American College of Sports Medicine for promoting maximal health and preventing diseases and injuries include resistance, cardiorespiratory, neuromata, and flexibility
The increased energy demands of exercise are fueled by energy substrates in the form of glucose and fats in the form of fatty acids
Both glucose and fatty acids are rich in chemical energy that must be converted into a form that cells can use, namely ATP (adenosine triphosphate)

29. Summary (Cont’d)
ATP, the primary energy currency of our cells, is produced in the body by three separate energy systems, two of which are anaerobic (not requiring oxygen) and occur in the cytosol of the cell, and one of which is aerobic (requiring oxygen) and occurs in the mitochondria
The energy contributions made through anaerobic and aerobic pathways combine to provide muscles with enough ATP to meet demands. The percentage or relative contribution of each depends on the intensity and duration of the activity
The anaerobic energy systems supply ATP quickly for high-intensity exercise, but only for a short time, and rely heavily on carbohydrates as fuel
Longer-lasting, lower-intensity activities rely almost entirely on the aerobic energy system, which produces ATP more slowly and utilizes a higher percentage of fat as a fuel source
Several methods can be used to estimate the intensity of aerobic activity. Two common methods are the Borg Rating of Perceived Exertion Scale and heart rate as a percentage of maximum heart rate

30. Summary (Cont’d)
The depletion of muscle glycogen during aerobic exercise is the most significant factor leading to exhaustion. Carbohydrate loading increases muscle glycogen stores, which can help athletes sustain and recover from high-intensity endurance exercise
Protein supplements are generally not warranted and alone do not cause muscle growth; protein intake must be combined with exercise—particularly strength training—and sufficient calorie intake to increase muscle mass
The goal of hydration during exercise is to limit fluid loss to less than 2% of body weight
Overhydrating through excess water consumption while exercising can be dangerous and lead to hyponatremia (low levels of sodium in the blood)
Individuals can reduce their risk of chronic disease and weight gain through moderate exercise for at least 30 minutes a day on most days of the week