The following mechanism has been proposed for | Ch 14 - 107AE

Nutrition Notes Week 13 Sports Nutrition A. Close relationship between nutrition and physical fitness B. Peak performance depends on a diet the supplies all the needed nutrients C. Physical activity, exercise, and physical fitness are not synonymous D. Physical activity refers to any movement of skeletal muscles that requires energy E. Exercise specifically refers to physical activities that are planned, repetitive, and intended to improve physical fitness An Intro to Physical Fitness A. Benefits of physical activity outweigh the risks for most Americans B. Guidelines 1. Adults should do 150 minutes per week of moderate-intensity 2. OR adults should do 75 minutes per week of vigorous-intensity aerobic physical activity 3. OR an equivalent combination of moderate and vigorous intensity aerobic activity 4. Episodes of at least 10 minutes, spread through the week C. The more you do, the better. There are more extensive health benefits D. Adults should also include muscle-strengthening activity that involved all major muscle groups on 2 or more days a week E. 80% of American adults fail to achieve levels of physical activity set forth in Physical Activity Guidelines Types of Exercise A. Anaerobic B. Aerobic- “with oxygen” 1. Moderate intensity a. Elevates heart rate and breathing (5-6 on RPE scale) b. Brisk walking, dancing, swimming, bicycling (level terrain) 2. Vigorous intensity a. Aerobic activity that greatly increases heart rate and breathing (7-8 on RPE scale) b. Jogging, tennis, swimming continuously, biking (mountainous) 3. Muscle-strengthening a. Increases skeletal muscle strength/power/endurance/mass b. Weight-lifting, etc. Muscular Fitness A. Strength is a maximal force a muscle can exert against a load at one time B. Endurance is the ability of the muscle to perform repeated, sub maximal contractions over time without becoming fatigued C. Power combines strength with speed for explosive movements such as jumping or throwing D. Flexibility is the ability to move a joint through its full range of motion. Poor flexibility is often linked to chronic pain, especially lower back Intensity Levels for Exercise A. Heart rate 1. Estimated maximal heart rate (MHR) = 220 - age 2. Rating of Perceived Exercise (PRE) is relative B. It’s all relative. Everyone has a different pain tolerance Energy for Muscle Work A. ATP- chemical energy 1. Generated from carbs, fat, proteins 2. Used by cells for muscle contractions 3. Only small amount is stored in resting cells (2-4 seconds worth of work) B. Other sources of energy are needed Ways to Generate ATP A. Phosphocreatine (PCr) 1. Anaerobic metabolism mechanism 2. High-energy compound formed and stored in muscle cells 3. PCr + ADP —> Cr + ATP 4. Activated instantly to replenish ATP 5. Sustains ATP B. Anaerobic Glycolysis 1. Has a limited amount of oxygen (intense physical activity- sprinting) 2. Produces 2 ATP per glucose 3. 5% of the potential energy from glucose 4. Replenishes ATP quickly 5. Cannot sustain ATP production 6. 30 seconds to make for 2 minutes of work C. Aerobic Glycolysis 1. Plenty of oxygen available 2. Low to moderate intensity 3. 28-30 ATP per glucose 4. about 95% of energy potential 5. Complete breakdown of glucose 6. Replenished slowly 7. Sustained ATP production 8. 2 minutes to make for 30 minutes of work 7. Generates lactate buildup by changing acidity that inhibits glycolytic enzymes Fuel mixture use depends on the intensity and duration of exercise A. High Intensity 1. Sprinting 2. Weight lifting 3. 30 seconds-2 minutes 4. Oxygen supply is limited (anaerobic) 5. Primarily use carbohydrate (glucose) as the source of energy 6. Glucose is coverted to 2 pyruvate (gain 2 ATP) which are converted to lactic acids, which can be converted back to glucose through the liver B. Low Intensity 1. Oxygen supply is sufficient to meet demand 2. Oxygen is used by mitochondria to produce more ATP from pyruvate 3. Can also use fat and protein (minor extent) to produce ATP C. Resting 1. More than half of energy comes from fat 2. Most of rest from glucose Metabolism of Fat for Food A. Majority of stored energy in the body B. Triglyceride —> 3 fatty acids + 1 glycerol C. Fatty acids are covered to ATP in the mitochondria of muscle cells D. Can generate 108 ATP for each 16 C fatty acid chain E. Trained muscles 1. Have more mitochondria 2. Have greater ability to use fat as fuel Fat Fuel A. Rate of fat use- dependent of concentration of fatty acids in the bloodstream B. Prolonged exercise-fat becomes main food source C. Intense activity- fat is not a major source of furor requires more oxygen Protein- Minor Source of Fuel A. During rest and low/moderate exercise (proved maybe 5% i energy needs) B. During endurance exercise (10-15% energy needs) C. Branched chain amino acids provide most of the energy Dietary Advice for Athletes A. Performance depends on athletic training and genetic makeup. However, diet can help maximize their potential B. A poor diet can seriously reduce performance Carbohydrates A. Before exercise 1. Especially important for 90-120 minutes events 2. 1-2 hour before exercise, low glycemic foods B. After exercise, lots of protein Carbohydrate Loading A. Beneficial for athletes who compete in continuous, intense, aerobic vexerce lasting more than 60-90 minutes B. The week before the event, taper down on exercise time and taper up on carbohydrate in diet C. Potential problem- water is added along with glycogen D. Can get similar benefits from consuming carbs in the event Protein A. Recommendation: 1-1.6 grams/kg B. Problems with high protein diets 1. Can increase calcium in urine 2. Increased urine production 3. Increased chance of kidney stones 4. It takes the place of carbs, could lead to early fatigue Vitamin and minerals A. For the most part, the needs for athletes are the same or slightly greater to sedentary adults B. Need for antioxidant maybe greater (vitamin C and E) Calcium A. Strenuous Exercise- loss through sweat B. Especially important to female athletes C. Female athletes who do not menstruate regularly are more at risk for bone fractures and osteoporosis later in life Iron A. Women are more susceptible to low iron B. Distance runner are at risk- some iron is lost in sweat, feet pounds on the ground can break red blood, intense training can lead to GI bleeding C. Sports anemia- inverse in blood volume Fluids A. Lose no more than 2% of body weight during exercise B. 2.5-3 cups for every 1 pound lost during or immediately exercise Glycogen- glucose storage A. Muscle glycogen (used only by that muscle) B. Liver glycogen is released into the blood stream C. During low to moderate intensity- can sustain work for up to 2 hours Glycogen Depletion A. “Hitting the wall”- depleted muscle glycogen B. “Bonking”- depleted liver glycogen Sports Drinks A. Sports drinks that require less than 60 minutes od exertion or toal weight loss is less than 5-6 pounds, the primary concern is replacing water B. Exercise beyond 60 minutes replacing carbohydrates and electrolytes become important Energy Bars A. Carbs or proteins or both B. Both seems to work better C. Tips for choosing a good energy bar D. 40 g CHO is less than/equal to 10 g protein and 4 g fat and 5 g fiber