The science of nutrition 4th edition thompson manore vaughan chapter 14

Chapter 14 Lecture

Chapter 14:
Nutrition and Physical Activity:
Keys to Good Health

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Physical Activity vs. Fitness

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Physical activity: any movement produced by muscles that increases energy
expenditure

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Leisure-time physical activity: any activity unrelated to a person's occupation

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Competitive sports
Recreational: hiking, walking, biking
Exercise: purposeful, planned, and structured

Physical Activity vs. Fitness (cont.)

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Physical fitness: the ability to carry out daily tasks with vigor and alertness without
fatigue

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Four components of physical fitness include cardiorespiratory fitness,
musculoskeletal fitness, flexibility, and body composition

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These are achieved through:

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Aerobic exercise
Resistance training
Stretching


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Benefits of Physical Activity

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Reduces the risk of heart disease, stroke, high blood pressure
Reduces the risk for obesity and type 2 diabetes
Reduces the risk for osteoporosis
May reduce the risk of colon cancer
Reduces the risk for osteoporosis
Improves sleep patterns, immune function
Reduces anxiety, stress, and depression

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Benefits of Physical Activity

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Despite the clear benefits of regular physical activity:

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Less than half of American adults do not do enough are physical activity
Nearly 23% of U.S. adults experience no leisure-time physical activity
Only 24% of girls and 35% of boys participate in daily physical education


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How Much Physical Activity Is Enough?

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Inactivity should be avoided
For substantial health benefits, adults should do a minimum of 150 minutes per
week of moderate-intensity or 75 minutes of vigorous intensity activity, or a
combination

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For additional health benefits, adults should increase the aerobic activity to 300
minutes per week of moderate-intensity or 150 minutes of vigorous activity

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Adults should participate in muscle strengthening activities

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How to Improve Fitness

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Assess current fitness level
Identify personal goals

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Specificity principle: specific actions yield specific results
Training: activity leading to skilled behavior

Make exercise program varied, consistent, and fun

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Intrinsic and extrinsic factors
Variety is important


How to Improve Fitness (cont.)

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Appropriately overloads the body

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Overload principle
FITT principle

Includes a warm-up and a cool-down period

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The FITT Principle

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Frequency: number of activity sessions per week
Intensity: amount of effort expended or how difficult the activity is to perform

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Intensities are termed low, moderate, or vigorous
Estimating maximal heart rate

Time of activity: how long a session lasts
Type of activity: a range of options

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Warm-up Period

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Warm-up and cool-down activities help you properly prepare for and recover from
an exercise session

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Warm-up (also called preliminary exercise)

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Should be brief, gradual, and gentle
Prepares muscles for activity by increasing blood flow and temperature
Enhances flexibility
Can help prepare you psychologically


Cool-down Period

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Done after an exercise session
Should be gradual and slow
Should include exercises from session, but at low intensity
Should include stretching
Helps prevent injuries
May reduce muscle soreness

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Tips to Increase Physical Activity

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Walk as often and as far as possible
Take the stairs at every opportunity
Take computer breaks to stretch, walk, or refresh yourself
Exercise while watching TV
Move around for everyday activities, like talking in your phone
Dance

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Fuel for Physical Activity

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Adenosine triphosphate (ATP): the energy-carrying molecule in the body (see Ch. 7)
ATP must be generated continuously since muscles store only enough ATP for 1–3
seconds of activity

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ATP is generated from the breakdown of carbohydrate, fat, and protein

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Fuel for Physical Activity

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After depleting ATP stores, muscles turn to other sources:

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Creatine phosphate (CP) stores some energy that can be used to make ATP
CP stores enough energy for 3−15 seconds of maximal physical effort; hence,
CP is used for very intense, brief activity bursts

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Breakdown of carbohydrates fuels both brief and long-term exercise


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Fuel for Physical Activity

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After creatine phosphate, glucose is the next source of energy for ATP production
Glucose provides ATP through glycolysis
Glucose source during exercise: muscle glycogen and blood glucose
Glycogen stores are limited

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Fuel for Physical Activity (cont.)

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Primary glycolysis end product: pyruvate
With limited oxygen, pyruvate is converted to lactic acid: a fuel source for working
muscles, heart, and resting tissues.

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Excess lactic acid goes back to the liver to be converted back into glucose via the
Cori cycle.

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The Cori cycle

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Fuel for Physical Activity (cont.)

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Glucose metabolism

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Anaerobic breakdown of glucose yields 2 ATP molecules
Aerobic breakdown of glucose yields 36–38 molecules of ATP

Glycogen storage is limited

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