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Chapter 9:

Chapter 9 Energy Supply and Fitness Copyright © 2012, 2007 Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 1


Energy As bodies function, chemical energy from food converted to mechanical energy and heat Kilocalorie (kcal): unit of energy measurement Methods to determine food energy Proximate composition Energy pathways ATP: fuel for all energy-requiring processes 2

Energy, cont’d:

Energy, cont’d Carbohydrate as Source of Energy Converted to carbon dioxide and water via metabolic pathways of Glycolysis, tricarboxylic acid (TCA) cycle Glycolysis: produces ATP and pyruvic acid Metabolism of glucose Anaerobic(no o2) breakdown glucose to yield 2ATP molecules Lactic acid produced Short term, high-intensity (sprinting) Aerobic (o2) breakdown…yeilds 36-38 molecules of ATP Co2 and H2o produced Mod. Intensity (hiking) 3

Energy, cont’d:

Energy, cont’d Fat can be metabolized to generate ATP Hydrolysis of fats into glycerol and 3 fatty acids Glycerol changed to pyruvic acid; used for energy Fatty acids enter the TCA cycle as two-carbon acetyl CoA units (beta oxidation) Protein as source of energy Amino acids: deamination Some amino acids converted to pyruvate or TCA cycle intermediates 4

Energy Balance:

Energy Balance Estimating daily needs To maintain a healthy weight our energy intake = energy expended Formulas Mult. Wt. by numbers on table 9-2 Ex 77 kg (170 lbs) man with mod exercise , needs 3160 kcal 5

Energy Balance, cont’d:

Energy Balance, cont’d Basal metabolism/basal metabolic rate (BMR) The amt of energy required to maintain life-sustaining activities Largest contributor to energy expenditure Factors affecting BMR: age, body size, sex, body temperature, fasting/starvation stress, menstruation, thyroid function, lean body mass Resting energy expenditure Physical activity Second largest contributor of energy expenditure Varies most: depends on intensity, duration, body size 6


Fitness Physical activity compared to physical fitness Physical activity: actions or movements made Physical fitness: limits on actions body is capable of making 7

Components of physical fitness :

Components of physical fitness Flexibility ability to move the muscles to full extent Muscular strength and endurance Ability of muscles to perform hard or prolonged work Cardiovascular endurance Ability of the body to take in and deliver o2 for physical work 8

Fitness, cont’d:

Fitness, cont’d Health benefits of physical exercise Regular exercise can: Improve cardiovascular fitness; inactivity major risk factor for CAD Decrease blood pressure Help lose and maintain weight Alter blood lipid and lipoprotein levels Reduce risk of colon cancer, stroke, Delay or treat type 2 DM, depression, osteoporosis 9

Fitness, cont’d:

Fitness, cont’d 2008 Physical Activity Guidelines for Americans Frequency and duration of exercise To reduce chronic disease risk To assist adult body weight management and avoid excessive body weight gain To maintain adult weight loss Intensity of exercise Type of activity 10

Fitness, cont’d:

Fitness, cont’d Sedentary people Physical activity as part of lifestyle activities (e.g., walking) Moderately active people Participate in 30-minute physical activity with minimum fatigue Cardiovascular and resistance exercise 11

Fitness, cont’d:

Fitness, cont’d Vigorously active people Recreational, competitive, elite, Olympic-level athletes For cardiovascular fitness, and to enhance performance Special populations Pregnant women and individuals with physical disabilities and health problems Strength training and Bodybuilding 12

Food and Athletic Performance:

Food and Athletic Performance Recommendations Dietary intake pattern: 45% to 65% of kcal CHO; 20% to 35% of kcal fat; 10% to 35% of kcal protein Some may need to adjust CHO to 60-70% Kcal requirements: balance energy expended Negative consequences with inadequate intake: weakness, iron deficiency, stress fractures, amenorrhea, osteoporosis Small meals and snacks provide needed kcal 13

Food and Athletic Performance, cont’d:

Food and Athletic Performance, cont’d Water: most critical for athletic performance Loss of 2% to 3% of body weight can impair ability Recommendations for adequate fluid replacement Tests for adequate hydration Sports drinks CHO: energy food Delays onset of fatigue Requirements for maintaining glycogen stores 14

Food and Athletic Performance, cont’d:

Food and Athletic Performance, cont’d Protein Protein requirements for athletes: 1.5 to 2 g/kg body weight (based on animal protein) Protein and amino acid supplements If protein needs are met by food, supplements treated as excess protein Protein (amino acids) does not increase muscle mass; need resistance strength training program and diet rich in complex carbohydrates 15

Food and Athletic Performance, cont’d:

Food and Athletic Performance, cont’d Fat Fat amount used depends on duration/ intensity of exercise, prior training, diet composition Aerobic activity promotes fat use as energy source Increases ability to burn fat as fuel; spares muscle glycogen Vitamins and minerals Excessive intake common among athletes “Thin-build” athletes at-risk for vitamin/mineral deficiencies; supplementation may be indicated (100% DRI) 16

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