Physical Activity and Nutrition

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Physical Activity and Nutrition

• Readings Chapter 14, pages 466 and 467, 471 -
  487
• Next Lecture Chapter 10, pages 307 - 335

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• an estimated 57 of Canadians are not physically
  active enough to benefit their health (2001 data)
• physical inactivity declined from 62 in 1994 to
  55 in 1998
• British Columbia has the lowest inactivity rate
  of Canadian provinces at 46
• its estimated that reducing the percent of the
  population that is physically inactive to 10
  would save approximately 5 billion in lifetime
  costs for medical care, sick leave, and lost tax
  revenues
• sedentary individuals have 50 more health
  problems than active individuals
• over one half of Canadians aged 5 - 17 are not
  active enough for healthy growth and development
• Canadian Fitness and Lifestyle Research
  Institute www.cflri.ca

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What is Physical Fitness?

• Definition
• the characteristics that enable the body to
  perform physical activity
• the ability to meet routine physical demands with
  enough reserve energy to rise to a physical
  challenge

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Benefits of physical fitness

• improved sleep
• nutritional health
• healthy body composition
• healthy bone mineral density
• improved immune function
• reduced risk of cardiovascular disease, Type II
  diabetes, and some cancers
• reduced stress and anxiety
• improved self-esteem and lowered risk of
  depression
• improved cognitive functioning, alertness and
  memory
• injury reduction and low back pain
• greater longevity and quality of life

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Sources of Energy During Physical Activity

• Physical activity increases the energy needs of
  working tissues including the muscles and the
  heartwhere does this energy come from?
• Quick Energy
  Compounds
• very small pool of ATP available in cells
• CP (creatine phosphate) can release phosphate
  which combines with ADP to form ATP but supplies
  are limited
• anaerobic

creatine phosphate ADP
creatine ATP
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Sources of Energy During Physical Activity

• 2. Carbohydrate
• derived from muscle and liver glycogen stores
• in activities of extreme intensity (20s to 3
  minutes)
• oxygen needs of muscle exceed the ability of
  cardiovascular system to supply oxygen
• glucose is used
  to produce ATP
• by product is
• in activities of high intensity (3 to 20
  minutes)
• glucose is used AEROBICALLY to produce ATP
• in activities of moderate intensity (gt 20
  minutes)
• glucose oxidation is supplemented with

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Sources of Energy During Physical Activity

• 3. Fat
• initially during exercise blood fatty acid
  decreases
• after 20 minutes there is an increase in release
  of fatty acids from stores
• due to actions of hormone
  (adrenalin)
• endurance training produces adaptations that
• increased size and number of
  is muscles
• increased number of capillaries to supply oxygen
  and nutrients to muscles

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Sources of Energy During Physical Activity

• 4. Protein
• contributes about 10 to energy expenditure both
  during activity and at rest
• Factors that influence protein use during
  activity
• high dietary protein use of
  protein as a fuel
• increased duration of activity
  protein use as a fuel
• increased intensity of activity
  protein use as fuel
• increased training (especially strength training)
  use of protein as fuel

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Influence of Intensity and Duration on Fuel Use
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Effect of Diet on Physical Endurance

• Maximum Endurance Time
• fat and protein diet
• normal mixed diet
• high carbohydrate diet

Figure 14-3, page 473
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Diet to Support Physical Activity

• Water
• nutrient required in largest amounts by the body
• needs increase during physical activity
• Body can lose water in four ways
• urine
• feces
• sweat
• respiration

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Diet to Support Physical Activity

• Water and Temperature Regulation
• heat production increases 15-20x during exercise
  compared to rest
• body cools itself by sweating
• 1 L of sweat dissipates about 600 kcal of heat
• prevents an increase in body temperature of about
  10C
• of sweat cools
  the body
• blood is rerouted through capillary beds that lie
  just beneath surface of skin to cool the blood
• endurance athletes can lose of
  water or more during each hour of activity

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Diet to Support Physical Activity

• Water and Temperature Regulation cont.
• in hot humid weather, need for water increases
  even more
• dehydration not only decreases performance but
  can cause dizziness, cardiac arrhythmias, muscle
  spasms, delirium, and death
• Hydration Schedule

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Diet to Support Physical Activity

• Electrolytes
• in addition to contributing to water loss, sweat
  also results in loss of ELECTROLYTES
• electrically charged minerals
• sodium, potassium, chloride, and magnesium
• minerals are important for water balance
• losses normally replaced through regular
• for exercises lasting longer than one hour,
  replacement of fluids with water AND electrolytes
  may provide a slight performance advantage
• more important for athletes in competitions
  lasting 4 hours with heavy sweating

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Diet to Support Physical Activity

• Energy Bars and Drinks
• during endurance activities lasting longer than
  one hour, glycogen supplies risk
• maintaining blood glucose levels can prolong time
  to exhaustion
• Replenishing Energy DURING activity
• glucose replacement (200 g) useful in activities
  lasting longer than 2 hours
• sports drinks with 6 - 10 carbohydrates (50 -
  100 kcal per cup)

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Diet to Support Physical Activity

• Replenishing Energy AFTER activity
• a high carbohydrate meal eaten within 15 minutes
  accelerates rate of glycogen storage by 300,
  called glycogen window
• Are energy bars or drinks necessary?

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Diet to Support Physical Activity

• Protein
• discuss previously in Lectures 8 and 9
• athletes have increased need for protein
• due to need to repair and build muscles after
  activity
• see Table 14-4 for recommended intakes
• Too much protein?
• supplements may result in
• dehydration
• displacement of carbohydrates from diet, may
  result in insufficient replenishment of glycogen
  stores
• kidney problems

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Diet to Support Physical Activity

• Vitamins and Minerals
• many vitamins and minerals are important for
  energy metabolism
• supplements DO NOT enhance physical performance
• impair
  performance
• Iron
• physically active young women prone to iron
  deficiency
• multiple contributing factors
• supplementation should be based on blood tests,
  not self-assessment