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

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

Components of Physical Fitness Physical activity Exercise

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

Types of Exercise

Types of Exercise

Types of Exercise

Types of Exercise

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

Energy-Producing Systems in the Body

Anaerobic Energy Systems Cytosol Creatine phosphate Glycolysis Pyruvate to lactate

Aerobic Energy Systems Mitochondria Pyruvate Fatty acids

Exercise Intensity and Energy Systems

Exercise Intensity and Fuel Utilization

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

Diet for Endurance Exercise Dietary carbohydrates Glycogen

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

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.

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 2-2.5 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.

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

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

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

Sports Supplements Ergogenic aids Caffeine Creative monohydrate

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

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

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)

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

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