CHAPTER 11

NUTRITION, EXERCISE AND SPORTS

LEARNING OUTCOMES

• Explain the benefits of physical activity• Discuss the energy sources for muscles and

human performance• Describe how the body responds to physical

activity• Describe main nutrition concepts used when

designing diet plans for athletes

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LEARNING OUTCOMES

• Describe the fluid needs of athletes and how to avoid dehydration and hyponatremia• Describe how the composition of food eaten

before, during and after exercise training sessions can effect performance• Explain the role of ergogenic aids and describe

their effect on athletic performance

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TRUE OR FALSE?

• Most people in the US are physically fit.• Athletes should eat immediately after training.• Vitamin and mineral supplements improve

athletic performance.• Everyone who exercises should consume sports

drinks.

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WHAT ARE THE BENEFITS OF EXERCISE?

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CHARACTERISTICS OF A GOOD FITNESS PROGRAM

• Mode• Duration• Frequency• Intensity• Progression• Consistency• Variety

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MODE

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DURATION AND FREQUENCY

• Dietary Guidelines• 30 minutes moderate physical activity for

disease prevention• 60 minutes moderate to vigorous activity for

weight control• 90 minutes moderate activity to maintain a

weight loss

• Frequency:• Most days of the week• Continuous or broken up?

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INTENSITY

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INTENSITY

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PROGRESSION, CONSISTENCY AND VARIETY

• Progression• Initiation (3-6 weeks): body adapts• Improvement (takes 5-6 months): maximize intensity and

duration• Maintain

• 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 is 5 times greater than ATP

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CARBOHYDRATE

• Major fuel for short-term, high-intensity and medium-term exercise• Anaerobic (short-term, high-intensity)• Glycolysis provides energy for 30 seconds to 2

minutes• Carbohydrate is only fuel that is used in this

process• Lactate is byproduct

• Aerobic (medium to high term)• ATP supply is slower but greater

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CARBOHYDRATE

• Glycogen: storage form on carbohydrate• Breaks down to glucose- used for anaerobic and

aerobic

• Muscle glycogen used for short events (<30 minutes)• Liver glycogen used for long events-will

start to use blood sugar for fuel• Exhaustion of glycogen stores: “Hitting the

wall”

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FAT

• Main fuel for prolonged low-intensity exercise (accounts for 50-90% of fuel in this type of activity)• Fat provides more

energy, but is less efficient

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FAT AS FUEL

• Training affects muscle use of fatty acids

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PROTEIN

• A minor fuel source during exercise (gluconeogenesis)• Eating more protein than what the body

needs will not build more muscle

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AMDR

• Acceptable Macronutrient Distribution Ranges for Adults (as a percentage of Calories) for “regular” adults.

• Protein: 10-35%• Fat: 20-35%• Carbohydrate: 45-65%

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DIETARY ADVICE FOR ATHLETES

• Protein Needs• 1-1.7 g/kg body weight• If an athletes needs are 2000kcals and she weighs 70kg, this

means she needs 70-120 grams (14- 24% of total kcal intake).

AMDR for Protein: 10-35%

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DIETARY ADVICE FOR ATHLETES

• Energy Needs vary widely• Carbohydrate Needs• 5-10 g/kg body weight depending on time/type of

exercise. If an athletes needs are 2000kcals and she weighs 70kg, this means she needs 380-680g.

Boosting Glycogen Stores• Carbohydrate Loading (What? Who? How?)

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DIETARY ADVICE FOR ATHLETES

• Fat Needs• 15-25%, emphasis on unsaturated fats

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FLUID NEEDS

• Need to replace fluids lost through sweat• Heat exhaustion• Heat cramps• Heat stroke

• Fluid Intake• Goal is to lose no more than 2% body weight• Before, during and after exercise• Drink 3 cups for every pound lost during

exercise

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HYDRATION

• Hyponatremia• Sports Drinks• Carbohydrates and

electrolytes (when needed?)

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FOOD INTAKE

• Pre-exercise meal• High carbohydrate, low fat

• Fueling during exercise• Carbohydrate replenishment for events longer than 60

minutes

• Recovery meals• 30 minutes and 2 hours after exercise 1-2 g of

carbohydrate per kg/body weight

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EXAMPLES

• Pre workout• Goal: keep up blood

sugar but don’t upset stomach

• Breakfast drinks• Cereal and milk, juice• Bread with peanut

butter• Pasta and milk• Baked potato w/sour

cream

• Post workout• Goal: Replace

glycogen stores to help recover

• Early simple carbs like juice, soda, sports drink, chocolate milk

• Later complex carbs like bread, potatoes, rice, pasta

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ERGOGENIC AIDS

• Substances taken to improve exercise performance• Useful in some situations• Creatine: increases phosphocreatine so may

improve performance in sports that require short bursts of energy, muscle gain is partially from increased water• Risks: kidneys

• Sodium bicarbonate: counter lactic acid buildup for activities where lactate is rapidly made (wrestling)• Risks: nausea and diarrhea

• Caffeine: stimulant, useful is some athletes who don’t regularly drink coffee- NCAA does test

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