NSC 170C1 1st Edition Lecture 25 Outline of Last Lecture I Focus on fitness Outline of Current Lecture I Carbohydrates II Fat as Fuel III Foods to eat before during and after exercise A effects Current Lecture Eat to Compete 25 I II Carbohydrates A Carbohydrate is the primary energy source during high intensity exercise i Obtained from blood glucose and from stored glycogen in muscles and liver ii Athletic training increases the amount of glycogen that muscles can hold well trained muscles can store 20 to 50 percent more iii Muscle glycogen is the preferred source of energy during exercise but liver glycogen is important for maintain blood glucose iv When glucose is broken down at a high rate muscles produce a by product called lactate a Lactate has been thought to negatively impact exercise performance however new research suggests it can be an important fuel during exercise B Fat is the primary energy source during low to moderate intensity exercise i Intensity and training affect how much fat you use ii In order to fully burn fat you must have a little glucose present C Protein is need primarily to build and repair muscle i The body can use protein for energy ii Very secondary How are carbohydrates fat and protein used during exercise A Eating and drinking supports physical activity by i Supplying the energy your body needs for the activity III IV ii Providing the nutrients that help you recover properly B Energy production during cardiorespiratory exercise is primarily aerobic because it uses oxygen C During the first few minutes of exercise energy production occurs under anaerobic conditions without oxygen D Anaerobic energy production relies on two high energy molecules in muscles cells i Adenosine triphosphate ATP adenosine molecule attached to a tail of three phosphates a Energy is released when phosphate is removed forms ADP b Supply supports only a few seconds of exercise ii Creatine phosphate creatine molecule attached to a single phosphate a Energy produced when phosphate is split off b Indirect energy produced when phosphate donated to ADP to regenerate ATP c Supply depleted after 10 seconds of intense exercise Exercise duration affects how much glucose and glycogen you use A Carbohydrate loading a training strategy used to build up muscle glycogen stores before a competition i Athletes in endurance events 90 minutes are likely to benefit the most B Simply carbohydrates bagel corn flakes baked potatoes best to eat before or immediately after exercise i Absorbed and enter bloodstream quickly for energy or to replenish glycogen C Complex carbohydrates oatmeal pasta rice corn best to eat a couple of hours before exercise i Carbohydrate content enters bloodstream more slowly becoming a sustained source of energy D Fat Is the Primary Energy Source during Low to Moderate Intensity Exercise i Even at rest the body uses fat as its main energy source ii Fat does not contain water so a greater amount can be stored iii Endurance training increases the body s utilization of fat for energy which spares glycogen Fat as Fuel A Fat as fuel must be accompanied by some glucose B Fatty acids come from 2 sources i fat stored within the working muscle ii fat stored under the skin V C Intensity of exercise i fatty acids can only be broken down aerobically D Duration of exercise i cells begin to release fatty acids approximately 20 minutes into exercise ii Untrained muscle a rely mostly on glycogen stores for energy and have greater lactic acid built up due to oxygen debt iii Trained muscle a burn fat more readily than untrained muscles because they develop more fat burning enzymes and heart and lungs more efficient in oxygen delivery E The Truth About the Fat Burning Zone i Should you reduce the intensity of your workout if you are trying to lose weight and body fat a The body burns a greater percentage of calories from fat when exercising at lower intensities b But you burn more total calories when exercising at a higher intensity which will help you meet weight loss goals c You don t need to stay in the fat burning zone to lose body fat you just need to burn enough calories for an overall calorie deficit F How Much Fat Do You Need for Exercise i Dietary recommendations for fat are 25 to 30 percent of total calories ii To promote heart health everyone should limit saturated fat to 10 percent of total calories a Limiting fat intake too much is undesirable and can lead to inadequate intake of calories essential fatty acids and fat soluble vitamins which can negatively affect athletic performance Protein Is needed primarily to build and repair muscle A Muscle damage is one of the most significant physiological effects of exercise B Protein stimulates remodeling of muscle cells increases strength and mass i Amino acids from proteins are the main nutrients necessary for muscle growth and recovery ii Carbohydrate helps promote muscle growth and recovery iii C D E F Glucose causes insulin response insulin an anabolic hormone The body can use protein for energy i The body prefers to use carbohydrate and fat as its main energy sources during exercise a Small amounts of protein are used only when calorie intake and carbohydrate stores are insufficient b If protein is used for energy it is not available to build and repair tissue and loss of muscle mass can occur ii Muscle protein is broken down into amino acids which are released into the bloodstream carried to the liver and converted to glucose for energy How Much Protein Do You Need for Exercise i Protein needs for athletes are not significantly higher than those for non exercisers ii Most recreational exercisers can easily meet the RDA for protein 0 8 g kg with a balanced diet iii Endurance athletes should consume 1 2 to 1 4 g kg protein iv Those doing significant resistance strength training may need 1 6 to 1 7 g kg protein Total Calorie Needs Depend on the Type and Schedule of Exercise i Examples a 1 hour of Frisbee 200 calories burned b 1 hour of downhill skiing 500 calories burned c Training schedule of Olympic athlete Michael Phelps 10 000 calories burned ii The best way to determine if you are consuming enough calories is to monitor your weight Timing of food intake affects fitness and athletic performance i Impacts energy levels and recovery time ii During exercise muscles are under a great deal of stress iii After exercise the body is in a catabolic breaking down state a Muscle and liver glycogen stores are low or depleted b Muscle