NUTR.2060 Lecture 11: Ch. 11: Nutrition, Exercise and Sports

6 Pages

Clinical Labratory & Nutritional Sciences
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Thomas Wilson

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Monday, April 10, 2017 Nutrition, Exercise and Sports Nutrition - Benefits of Fitness • Cardiovascular health, improved body composition, blood glucose control, better sleep, and more… • Healthy People 2020 objectives include: - Reduce the number of adults engaging in no leisure-time physical activity - Increase the proportion of adults who meet current federal physical activity guidelines for aerobic and muscle-strengthening activity • 2008 Physical Activity Guidelines for Americans - Engage in 150 min of moderate or 75 min of vigorous aerobic activity, or some combination per week - Perform muscle-strengthening activities 2+ days per week - Characteristics of a Good Fitness Program • Perform various type of exercise • Duration >30 min • Frequency depends on type (2-3 times vs 3-5 times per week) • Intensity: low, moderate, high - Measured by: heart rate, perceived exertion rate, oxygen consumption Progression • - Initiation phase (first 3-6 weeks) - Improvement phase • Make it a daily routine - Achievement and Maintenance of Fitness • If you have been sedentary for many years, discuss fitness program with a health- care provider first 1 Monday, April 10, 2017 • Assess and record baseline fitness scores • New program should start slowly with shorter intervals • Include warm up and cool down periods - Energy Sources for Muscle Use • ATP: Immediate usable energy - Lasts 2-4 seconds Phosphocreatine (creatine phosphate): initially resupply of muscle ATP • - Re-forms ATP - Concentration in muscle in 5 times greater than ATP - Made from amino acids from the diet; some people take creatine supplements - Carbohydrate • Major fuel for short-term, high-intensity, and medium-term exercise • Glycogenolysis first then glycolysis • Anaerobic activities (short/intense) - Glycolysis provides energy for 3 sec to 2 min - Lactate produced • Aerobic activities (medium/less intense) - ATP supply is produced slower but in greater amounts - Muscle Glycogen vs. Blood Glucose as Muscle Fuel • Muscle glycogen fuels muscle cells - Important in all exercises especially short-term exercise (<30 min) • Higher % of energy in anaerobic activities; decreases overtime in aerobic activities • Liver glycogen maintains blood glucose - Provides fuel for muscle cells in longer duration exercises • Depletion of glycogen stores: 2 Monday, April 10, 2017 - In muscles: fatigue - In liver: hypoglycemia - In both: “Hitting the wall” - Fat • Main fuel for at rest or prolonged low-moderate intensity exercises • Fat metabolism provides more energy than carbohydrates but is less efficient - Only aerobic activities (longer/less intense) • Training affects muscle use of fatty acids - The more trained, the greater efficiency a muscle has to use fatty acids as a fuel - Training increases • Size and number of mitochondria • Levels of enzymes for aerobic metabolism • Muscle myoglobin (Stores O ) 2 - Protein • A minor fuel source during most exercises (5%) - More in endurance long-term exercises (up to 15%) • Energy comes from the branched chain amino acids mostly - Directly or via gluconeogenesis (liver) to make glucose Eating more protein than what the body needs alone will not increase muscle
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