NSC 170C1 1st Edition Lecture 25 Outline of Last Lecture I. Focus on fitnessOutline of Current Lecture I. CarbohydratesII. Fat as FuelIII. Foods to eat before, during, and after exercise A. effectsCurrent LectureEat to Compete- 25 I. Carbohydrates A. Carbohydrate is the primary energy source during high-intensity exercise i. Obtained from blood glucose and from stored glycogen in musclesand liverii. Athletic training increases the amount of glycogen that muscles can hold; well-trained muscles can store 20 to 50 percent moreiii. 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 lactatea) Lactate has been thought to negatively impact exercise performance; however, new research suggests it can bean important fuel during exerciseB. Fat is the primary energy source during low to moderate intensity exercise i. Intensity and training affect how much fat you useii. 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 secondaryII. How are carbohydrates, fat and protein used during exercise?A. Eating and drinking supports physical activity byi. Supplying the energy your body needs for the activityii. Providing the nutrients that help you recover properlyB. 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 phosphatesa) Energy is released when phosphate is removed, forms ADPb) Supply supports only a few seconds of exerciseii. Creatine phosphate: creatine molecule attached to a single phosphatea) Energy produced when phosphate is split offb) Indirect energy produced when phosphate donated to ADP to regenerate ATPc) Supply depleted after 10 seconds of intense exerciseIII. Exercise duration affects how much glucose and glycogen you useA. Carbohydrate loading: a training strategy used to build up muscle glycogen storesbefore 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 glycogenC. Complex carbohydrates (oatmeal, pasta, rice, corn) best to eat a couple of hours before exercisei. Carbohydrate content enters bloodstream more slowly, becoming a sustained source of energyD. Fat Is the Primary Energy Source during Low- to Moderate-Intensity Exercisei. Even at rest, the body uses fat as its main energy sourceii. Fat does not contain water, so a greater amount can be storediii. Endurance training increases the body’s utilization of fat for energy, which spares glycogenIV. Fat as FuelA. Fat as fuel must be accompanied by some glucoseB. Fatty acids come from 2 sourcesi. fat stored within the working muscleii. fat stored under the skinC. Intensity of exercisei. fatty acids can only be broken down aerobicallyD. Duration of exercisei. cells begin to release fatty acids approximately 20 minutes into exerciseii. Untrained musclea) rely mostly on glycogen stores for energy and have greater lactic acid built up due to oxygen debtiii. Trained musclea) burn fat more readily than untrained muscles because they develop more fat-burning enzymes, and heart and lungs more efficient in oxygen deliveryE. The Truth About the Fat-Burning Zonei. 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 intensitiesb) 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 deficitF. How Much Fat Do You Need for Exercise?i. Dietary recommendations for fat are 25 to 30 percent of total caloriesii. To promote heart health, everyone should limit saturated fat to 10 percent of total caloriesa) 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 performanceV. Protein Is needed primarily to build and repair muscleA. Muscle damage is one of the most significant physiological effects of exerciseB. Protein stimulates remodeling of muscle cells, increases strength and massi. Amino acids from proteins are the main nutrients necessary for muscle growth and recoveryii. Carbohydrate helps promote muscle growth and recoveryiii. Glucose causes insulin response, insulin an anabolic hormoneC. The body can use protein for energyi. The body prefers to use carbohydrate and fat as its main energy sources during exercisea) 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 tobuild and repair tissue and loss of muscle mass can occur.ii. Muscle protein is broken down into amino acids, which arereleased into the bloodstream, carried to the liver, and converted to glucose for energy.D. How Much Protein Do You Need for Exercise?i. Protein needs for athletes are not significantly higher than those for non-exercisersii. Most recreational exercisers can easily meet the RDA for protein (0.8 g/kg) with a balanced dietiii. Endurance athletes should consume 1.2 to 1.4 g/kg proteiniv. Those doing significant resistance/strength training may need 1.6 to 1.7 g/kg proteinE. Total Calorie Needs Depend on the Type and Schedule of Exercisei. Examples:a) 1 hour of Frisbee = 200 calories burnedb) 1 hour of downhill skiing = 500 calories burnedc) Training schedule of Olympicathlete Michael Phelps = 10,000calories burnedii. The best way to determine if youare consuming enough calories isto monitor your weightF. Timing of food intake affects fitness and athletic performancei. Impacts energy levels and recovery timeii. During exercise, muscles are under a great deal of stress.iii. After exercise, the body is in a catabolic