Transcript Document 7268592

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Benefits of Fitness
• Cardiovascular, body composition, blood glucose
control, sleep habits and more…
• Healthy People 2020
– Objectives
• 2008 Physical Activity Guidelines for Americans
– Adults should be physically active
– Engage in 150 min of moderate-intensity or 75 min
vigorous aerobic activity, or combination
• Double the times for even more health benefits
– Perform muscle-strengthening activities 2+ days/wk
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Characteristics of a Good
Fitness Program
• Mode
– Aerobic, Resistance and Flexibility
• Duration
• Frequency
• Intensity
– Rating of Perceived Exertion (RPE)
– VO2max
– Metabolic equivalents (METs)
• Progression
• Consistency
• Variety
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Energy Sources for Muscle Use
• ATP: Immediately usable energy
– Lasts 2-4 seconds
• Phosphocreatine: Initial resupply of muscle
ATP
– Re-forms ATP from ADP
– Concentration in muscle is 5 times greater than ATP
– Made from amino acids from the diet; some take
supplements
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Carbohydrate
• Major fuel for short-term, high-intensity,
and medium-term exercise
• Anaerobic pathway
– Glycolysis provides energy for 30sec to 2min
• Aerobic pathway
– ATP supply is slower but greater
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Muscle Glycogen vs. Blood
Glucose as Muscle Fuel
• Muscle glycogen fuels muscle cells
– Important in short-term exercise (<30min)
• Liver glycogen maintains blood glucose
– Provides fuel for muscle cells in longer-term
exercise
• Depletion of glycogen stores:
– In muscles: fatigue
– In liver: hypoglycemia
– In both: “Hitting the wall”
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Fat
• Main fuel for prolonged low-intensity
exercise
• Fat metabolism provides more energy than
carbohydrates but is less efficient
• Training affects muscle use of fatty acids
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Protein
• A minor fuel source during exercise (5%)
– More in endurance exercise (up to 15%)
• Energy comes from the branched chain
amino acids
– Directly or via gluconeogenesis
• Eating more protein than what the body
needs will not increase muscle mass
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The Body’s Response to
Physical Activity
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Specialized Functions of
Skeletal Muscle Fiber Types
• Type I
• Type IIA
• Type IIX
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Adaptation of Muscles and
Body Physiology to Exercise
• Hypertrophy
• Atrophy
• Increased blood
volume, capillary
number, bone
density, and
stronger heart
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Dietary Advice for Athletes
• Energy Needs
• Carbohydrate Needs
– 7-10g/kg body weight
• Boosting Glycogen Stores
– Carbohydrate (Glycogen) Loading
• Fat Needs
– 15-25% of kcal
• Protein Needs
– 1.2-1.7 g/kg body weight
• Vitamin and Mineral Needs
– Iron deficiency and impaired performance
– Calcium and the Female Athlete Triad
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Fluid Needs of Active
Individuals
• Fluids lost through sweat need to be replaced
– Dehydration
– Heat exhaustion, heat cramps, heatstroke
• Fluid Intake
– Goal is to lose no more than 2% body weight
– Thirst – a late sign of dehydration
– Replace fluid before, during and after exercise
• Water Intoxication
• Sports Drinks
– Carbohydrates and electrolytes
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Food Intake:
Before, During, and After Exercise
• Pre-exercise meal
– High carbohydrate, non-greasy, non-gas
producing, and easily digested
• Fueling during Exercise
– Carbohydrate replenishment during events
longer than 60 minutes improves performance
• Recovery meals
– Within 30 minutes and 2 hours after exercise
– 1-1.5g carbohydrate per kg/body weight
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