Introduction to Exercise Physiology

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Introduction to Exercise Physiology

• Hippocrates (460 -377 BC)
• Father of Preventative Medicine
• Galen (131 - 201 AD)
• most well-known influential physician
• Laws of Health

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Galen

• Wrote about
• benefits of exercise
• deleterious effects of sedentary living

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Galen

• Surgically repaired torn tendons muscle
• Recommended rehabilitation therapies
• Recommended exercise regimes

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Laws of Health (circa 140 AD)

• 1. Breathe fresh air
• 2. Eat proper foods
• 3. Drink the right beverages
• 4. Exercise
• 5. Get adequate sleep
• 6. Have a daily bowel movement
• 7. Control ones emotions

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Exercise Physiology History

• Harvard (late 19th century)
• Department of Anatomy, Physiology, and Physical
  Training
• B.S Degree (1891 - 1898)

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This Course in Exercise Physiology

• Designed to heighten your awareness of
• General Health and Wellness
• Preventative Medicine

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Nutrition I

• Galen
• Eat proper foods
• Drink the right beverages

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Macronutrients

• Carbohydrates (CHO)
• Lipids
• Proteins

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Function of Macronutrients

• Structural
• Functional

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Common Element

• Carbon (C)

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Carbohydrates (CHO)

• Carbon (C)
• Hydrogen (H)
• Oxygen (O)
• (CH2O)n

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Monosaccharides

• single sugar molecule
• basic unit of CHO
• categorized by of carbons
• - trioses
• - tetroses
• - pentoses
• - hexoses

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Monosaccharides

• glucose (dextrose) - blood sugar
• fructose - fruit sugar
• galactose - milk sugar

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Glucose

• main energy source
• produced
• - thru digestion of complex CHO
• - in liver via gluconeogenesis

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Glucose

• absorbed in small intestine

Cells
Lipids
Glycogen
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Oligosaccharides

• disaccharides

GLUCOSE
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Polysaccharides
Polysaccaharides
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Plant Polysaccharides
Plant Polysaccaharides
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Starch

• storage form of CHO
• complex CHO
• most impt. dietary source of CHO
• grain ? bread, cereal, pasta

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Fiber

• Nonstarch polysaccharide
• resistant to human digestion
• make up structural components of plants
• cellulose

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Fiber

• Linked w/ lower obesity, DM, intestinal
  disorders, HD, serum cholesterol
• aid in gastrointestinal function (bulk)
• - scraping gut wall
• - dilute harmful chemicals
• - ? transit time
• ? rate of digestion of CHO

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Animal Polysaccharides
Stored Glucose
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CHO in the body
375 - 475 grams
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Glycogen Utilization

• directly by muscle
• liver ? blood glucose (glyogenolysis) ? muscle

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Glycogen Regulation

• ? blood glucose ? ? insulin (pancreas?)
• ? cellular uptake of blood glucose

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Glycogen Regulation

• ? blood glucose ? ? glucagon (pancreas?)
• ? break-down of glycogen ? blood glucose

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Glycogen Regulation

• very sensitive to changes in diet
• - depleted quickly
• - reserved quickly
• upper limit 15g /1 kg
• excess is stored as lipids

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CHO intake

• 40 - 60
• sucrose (table sugar) vs. fructose (plant sugar)
• fructose
• - fewer calories
• - does not stimulate insulin secretion
• - taken up by muscle w/o insulin ? stable
  blood glucose

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Role of CHO

• energy source
• preserve tissue proteins (structure)
• CHO starvation ? gluconeogenesis
• - protein ? glucose
• - glycerol (lipids) ? glucose

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Role of CHO

• allows for efficient lipid metabolism
• ? blood glucose ? lipid mobilization ?
• incomplete lipid catabolism ? ketone bodies
  (ketosis / acidosis)
• seen w/
• - CHO starvation
• - DM

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Role of CHO

• proper function of CNS
• efficient nerve tissue metabolism

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CHO and Exercise

• ? activity
• - ? use of muscle glycogen (anaerobic)
• - ? release of glucose (liver)

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CHO and Exercise

• Intense exercise
• - BG supplies 30 energy
• - muscle glycogen is majority
• 1 hour of intense exercise
• 55 ? glycogen
• 2 hours
• 100 ?
• use of BG ?

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CHO and Exercise

• Moderate exercise
• - initially all glycogen
• - later 40-50 glycogen / lipid breakdown
• - later - ? glycogen ? ?lipid breakdown

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CHO and Exercise

• Continued exercise
• - depletion of glycogen and BG ? fatigue
  (bonking)

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CHO and Exercise
Heavy Exercise
Moderate Exercise
Mild Exercise
Felig P, Wahren J. Fuel Homeostasis in exercise.
N. Engl. J Med., 293 1078, 1975.
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Effect of Diet on Muscle Glycogen

• diet low in CHO ? quicker time to fatigue
• high fat/low CHO diets ? ? energy ? ? endurance

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Effect of Diet on Muscle Glycogen
Bergstrom J. et. al. Diet, muscle glycogen and
physical performance. Acta Physiol. Scand., 71
140, 1967.
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Lipids (Fats)

• same elements as CHO
• different linking and gt HO ratio

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Lipids
Lipids
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Simple Lipids

• triglycerides - most plentiful
• gt 95 of body fat

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Triglycerides

• glycerol
• fatty acids

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Fatty Acids

• saturated
• - holds many H atoms
• - animal products

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Fatty Acids

• unsaturated
• - usually plant sources
• - mono- canola, olive peanut
• - poly- safflower, sunflower, soybean, corn
• - hydrogenation - saturated-like (margarine,
  lard)

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Compound Lipids

• triglyceride other chemicals
• phospholipids (phosphate nitrogenous base)
• - help control movement across cell membrane
• - structural integrity
• - blood clotting
• - myelin sheaths

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Compound Lipids

• Glycoproteins (CHO N)
• Lipoproteins (protein triglycerides /
  phosolipids)
• - main form of lipid transport

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Lipoproteins

• Chylomicrons - transports lipid-soluble vitamins
  (A, D, E, K)
• HDL - 50 protein / 20 lipid / 20 cholesterol
• LDL
• VLDL - 95 lipid - transports triglycerides

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HDL vs. LDL

• LDL
• - deliver cholesterol to arterial walls
• - structural changes in walls
• HDL
• - reverse transport of cholesterol ? liver

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HDL vs. LDL

• Total cholesterol is not the issue
• ratio of HDL to LDL
• ? HDLLDL ? ? risk of CAD
• ? exercise ? smoking ? ? HDL

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Derived Lipids

• from simple compound lipids
• cholesterol - only in animals

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Cholesterol

• found in plasma membrane
• exogenous - obtained thru diet
• endogenous - synthesized by cells

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Cholesterol

• endogenous - produced by
• - liver (70)
• - arterial walls
• - intestinal walls

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Functions of Cholesterol

• building of plasma membranes
• precursor for
• vitamin D
• adrenal gland hormones
• estrogen, androgen, progesterone
• impt. in formation of bile
• egg yolk, red meat, organ meat, shellfish, dairy
  products

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Cholesterol and CAD

• ? serum cholesterol ? LDL ? ?CAD
• other risk factors genetics, HBP, smoking,
• reduce cholesterol thru
• - diet (? saturated fat / ? unsaturated fat)
• - exercise and weight control
• - medication
• 12 (cholesterol reductionCAD risk)

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Dietary Intake of Lipids

• ? 30 of total energy content
• - 70-80 unsaturated fats
• - (mono poly)

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Role of Lipids

• largest store of energy
• protection
• thermal insulation

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Lipids as an Energy Source

• 1 gram yields 9 calories
• at rest can yield 80-90 of energy
• concentrated energy source
• - high in H
• - relatively low H2O
• 50x gt caloric reserve in fat than CHO
• spares use of protein as energy

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Lipids and Vitamins

• Transport medium for fat soluble vitamins (A, D,
  E, K)

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Lipids and Diets

• ? 3.5 hours to digest
• reduce hunger

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Lipids and Exercise

• Light to moderate exercise utilizes FFA
• initiation of exercise
• - initial ? in serum FFA
• - ? sympathetic hormones / ? insulin
• - FFA release from adipose

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Lipids and Exercise

• moderate exercise for lt 1 hour
• CHO and lipid utilization is
• gt 1 hour
• gt use of lipids as CHO deplete
• continued moderate exercise
• lipids may provide 80 of energy

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Lipids and Exercise Intensity

• ? intensity
• - lipid utilization remains same
• - blood glucose muscle glycogen ?
• _at_ 25 or 85 of max. exercise ? lipid utilization
  remains same

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Lipids and Exercise Intensity

• trained individuals - more efficient
• - mobilizing FFA
• - utilizing FFA
• conserve glycogen reserves

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Lipids and Exercise Intensity
Lipid
Tissue O2 uptake (mL/kg.min)
Saltin B, Astrand PO. Free fatty acids and
exercise. Am. J. Clin. Nutr., 57(suppl) 752S,
1993)
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Training Effect

• ? enzymes responsible for producing energy
• improved transport of FFA thru membranes
• altered transport of FFA (? proteins enzymes)
• proliferation of capillaries (vascularization)

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Cellular Phones
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Proteins

• C, H, O, N (16), S, P, Fe
• amino acids chains

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Amino Acids

• 8 essential (9 children)
• nonessential - synthesized

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Proteins

• Sources
• - eggs, milk, meat, fish, poultry
• - 67 from animals
• - cholesterol
• - saturated fat
• - animal sources more complete
• - vary plant sources to achieve variety

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Proteins

• Plant sources
• - often high in CHO / fiber, vitamins
• - low in cholesterol

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Protein Consumption

• excessive amounts not necessary
• 0.8 0.9 grams/kg BW
• 2-4 grams/kg of BW (infants/children)
• 20 grams pregnancy
• 10 grams - nursing

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Amino Acid Supplementation

• has NOT demonstrated
• - increased muscle mass
• - improved muscular strength, power, or
  endurance

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Protein in the Body

• found in
• - blood plasma
• - visceral tissue
• - muscle
• functional structural roles ? no stores

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Role of Amino Acids/Protein

• 12-15 of body mass
• building blocks of tissue (anabolism)
• cells plasma membrane, internally
• collagen in hair, skin, etc.
• enzymes

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Role of Amino Acids/Protein

• blood plasma proteins
• -hemoglobin
• genetic material (RNA/DNA)
• buffering
• muscle actin, myosin

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Protein Metabolism

• catabolized _at_ rest for energy (2-5)
• deaminized first ? urea ? urine
• excessive protein catabolism ? excessive H20 loss

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Protein Utilization during Exercise
Sweat urea nitrogen (mg/h)
Lemon PWR, Nagel F. Effects of exercise on
protein and amino acid metabolism. Med. Sci.
Sports Exerc., 13 141, 1981.
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Protein Utilization during Exercise
Alanine output from legs (mM/min.)
Felig P, Wahren J. Amino acid metabolism in
exercising. J. Clin. Invest. 50 2703, 1971.
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Protein Metabolism

• Nitrogen balance
• - nitrogen (protein) in nitrogen out
• Positive nitrogen balance
• - nitrogen in gt nitrogen out
• - children
• - pregnancy
• - recovery
• - 20 to resistance training

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Protein Metabolism

• Negative nitrogen balance
• - nitrogen in lt nitrogen out
• - protein used as 10 energy source
• - starvation dietary implications ? loss of
  LBM

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Protein Metabolism Summary

• occurs during endurance and resistance training
  exercise for energy utilization
• 20 CHO/Glycogen depletion
• additional quantities for heavy resistance
  training???
• additional food intake will probably provide
  enough CHO and protein