Chapter 14 Nutrition and Physical Activity Keys to Good Health What Fuels our Activities Carbohydrates fats and even small amounts of proteins ATP very limited keeps muscles active for only 1 3 seconds The ATP CP Energy System Uses Creatine Phosphate to Regenerate ATP When more energy is needed a high energy compound creatine phosphate can be broken down to support the regeneration of ATP o Anaerobic reaction without oxygen o Maximal physical effort for about 3 15 seconds The Breakdown of Carbohydrates Provides Energy for Both Brief and Long Term Exercise The most commons source of glucose during exercise comes from glycogen stored in the muscles and glucose found in the blood For every glucose molecule that goes through glycolysis two atp molecules are produced The primary end product of glycolysis is pyruvate The major advantage of glycolysis is that it is the fastest way to generate atp for exercise o Generally less than 3 minutes One glucose molecules going through aerobic metabolism yields 36 38 atp for energy whereas the anaerobic process yields only about 2 atp molecules The cori cycle the metabolic pathway by which excess lactic acid can be converted into glucose in the liver Aerobic Breakdown of Fats Supports Exercise of Low Intensity and Long Duration When we refer to fat as a fuel source we mean stored triglycerides o LONG TERM ACTIVITY Fat is an abundant source even in lean people Fat provides 9 kcal or energy per gram more than twice as much energy per gram as carbs o Disadvantage the process is relatively slow Primary source of energy during rest sitting and standing in place Amino Acids Are Not Major Sources of Fuel During Exercise Vigorous Exercise Increase Energy Needs Athletes generally have higher energy needs than moderately active or sedentary people The energy needs of male athletes are high than those of female athletes Carbohydrate Needs Increase for Many Active People Amdr for carbohydrates is 45 65 of total energy intake Muscle glycogen storage during the first 4 6 hours of recovery In general complex less processed carbohydrate foods such as whole grains and cereals fruits vegetables and juices are excellent sources that also supply fiber vitamins and minerals Carbohydrate Loading glycogen loading involves altering both exercise duration and carbohydrate intake such that it maximizes the amount of muscle glycogen o Do not always improve performance o Side effects diarrhea heavy bloated sluggish Moderate Fat Consumption Is Enough to Support Most Activities When reach a physical trained state able to use more fat for energy Better fat burners o Increase in the number and activity of various enzymes involved in fat metabolism improved ability of the muscles to store fat and improved ability to extract fat from the blood for use during exercise o Spare carbs to use during prolonged intense training or competition Many Athletes Have Increased Protein Needs Those who are already trained need less protein than those who are initiating training Zone diet o 40 30 30 diet 40 carb 30 fat 30 protein Not true People of all fitness levels can consume more than enough protein without the use of supplements or specifically formulated foods Regular Exercise Increases Our Need for Fluids Functions of water o Lubricant that bathes the tissues and cells o Transport medium for nutrients hormones and waste products o And important component of many chemical reactions energy production o Structural part of body tissues such as proteins and glycogen o Vital component in temperature regulation Heat sycope dizziness that occurs when people stand for too long in the heat and the blood pools in their lower extremities rather than fully supplying their brains Heat cramps muscle spasm that occur during exercise or even several hours after strenuous exercise concentrating Heat exhaustion excessive sweating weakness nausea dizziness headache and difficulty Heat stroke hot dry skin rapid heart rate vomiting diarrhea increase in body temperature Avoid losing more than 2 3 of body weight during exercise Longer than 1 hour in any weather sports beverages containing carbs and electrolytes are recommended Inadequate Intakes of Some Vitamins and Minerals Can Diminish Health and Performance When individuals train vigorously for athletic events their requirements for certain vitamins and minerals may be altered o B vitamins o Calcium and the female athlete triad o Iron Iron needs cannot be met through the diet and supplementation is necessary
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