Introduction to Exercise Physiology
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Transcript of Introduction to Exercise Physiology
Introduction to Exercise Physiology
Hippocrates (460 -377 BC) “Father of Preventative Medicine”
Galen (131 - 201 AD) most well-known & influential
physician “Laws of Health”
Galen Surgically repaired torn tendons &
muscle
Recommended rehabilitation therapies
Recommended exercise regimes
Laws of Health (circa 140 AD)
1. Breathe fresh air2. Eat proper foods3. Drink the right beverages4. Exercise5. Get adequate sleep6. Have a daily bowel movement7. Control one’s emotions
Exercise Physiology History
Harvard (late 19th century)
Department of Anatomy, Physiology, and Physical Training
B.S Degree (1891 - 1898)
This Course in Exercise Physiology
Designed to heighten your awareness of:
General Health and Wellness
Preventative Medicine
This Course in Exercise Physiology
Identify strengths & weaknesses of the latest fitness “crazes” and diets
Monosaccharides single sugar molecule basic unit of CHO categorized by # of carbons:
- trioses- tetroses- pentoses- hexoses
Glucose main energy source produced :
- thru digestion of complex CHO
- in liver via gluconeogenesis
Fiber Nonstarch polysaccharide resistant to human digestion make up structural components of
plants cellulose
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
Glycogen Regulation very sensitive to changes in diet
- depleted quickly- reserved quickly
upper limit = 15g /1 kg
excess is stored as lipids
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
Role of CHO energy source
preserve tissue proteins (structure)
CHO starvation gluconeogenesis- protein glucose- glycerol (lipids) glucose
Role of CHO allows for efficient lipid metabolism blood glucose lipid mobilization incomplete lipid catabolism ketone
bodies (ketosis / acidosis) seen w/:
- CHO starvation- DM
CHO and Exercise
Intense exercise (> 80% HRmax): Initially (5-10 min.) mm. glycogen via
anaerobic means 1 hour of intense exercise
55% glycogen 2 hours
100% use of BG
CHO and Exercise
Moderate exercise (60-79% HRMax) initially all glycogen later 40-50% of energy is glycogen
/ lipid (aerobic) later - glycogen BG and lipid
CHO and Exercise
Continued exercise: depletion of glycogen and BG
systemic fatigue (“bonking”, “hitting the wall”)
CHO and Exercise
In general, w/ an activity : use of muscle glycogen (anaerobic
glycolysis) as initial energy concurrent release of glucose (liver)
Effect of Diet on Muscle Glycogen diet low in CHO quicker time to
fatigue
high fat/low CHO diets energy endurance
Effect of Diet on Muscle Glycogen
Initial muscle glycogen (g/100 g muscle)
Tim
e to
exh
aust
ion
(min
utes
)
1 4
50
200
Low CHO
Normal Diet
High CHO
Bergstrom J. et. al. Diet, muscle glycogen and physical performance. Acta Physiol. Scand., 71: 140, 1967.
CHO and Exercise
What nutrient to use is determined by:1. Exercise intensity2. Exercise duration3. Fitness status4. Nutritional status
CHO Balance & Exercise
Fuel
Exercise
sympatheticresponse
LiverGlycogenoly
sisAnaerobic
Glucose
BG
glycogenphosphorylase
Muscle Glycogenolysi
sAnaerobic
Glucose
LipidsGlucose BG
CHO and Exercise
Exercise Time (minutes)
Leg
Glu
cose
Upt
ake
(mM
/min
)
10 40
1.0
4.0Heavy Exercise
Moderate Exercise
Mild Exercise
Felig P, Wahren J. Fuel Homeostasis in exercise. N. Engl. J Med., 293: 1078, 1975.
Fatty Acids unsaturated
- usually plant sources- mono- canola, olive peanut- poly- safflower, sunflower,
soybean, corn- hydrogenation - saturated-
like (margarine, lard)
Compound Lipids triglyceride + other chemicals phospholipids (phosphate &
nitrogenous base)- help control movement
across cell membrane- structural integrity- blood clotting- myelin sheaths
Compound Lipids Glycolipids (FA + CHO + N) Lipoproteins (protein +
triglycerides / phosolipids)- main form of lipid transport
Lipoproteins Chylomicrons - transports lipid-
soluble vitamins (A, D, E, & K) HDL - 50% protein / 20% lipid /
20% cholesterol LDL VLDL - 95% lipid - transports
triglycerides
HDL vs. LDL LDL
- deliver cholesterol to arterial walls- structural changes in walls
HDL- “reverse transport of cholesterol” liver
HDL vs. LDL Total cholesterol is not the issue
ratio of HDL to LDL
cholesterol:HDL (HDL:LDL) risk of CAD
exercise & smoking HDL
Cholesterol found in plasma membrane
exogenous - obtained thru diet
endogenous - synthesized by cells
Functions of Cholesterol building of plasma membranes precursor for
vitamin Dadrenal gland hormonesestrogen, androgen, progesterone
impt. in formation of bile egg yolk, red meat, organ meat,
shellfish, dairy products
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
1:2 (cholesterol reduction:CAD risk)
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 > caloric reserve in fat than CHO spares use of protein as energy
Lipids and Exercise
Light to moderate exercise utilizes FFA
initiation of exercise:- initial in serum FFA- sympathetic hormones /
insulin- FFA release from adipose
Lipids and Exercise
moderate exercise for < 1 hour:CHO and lipid utilization is =
> 1 hour:> use of lipids as CHO deplete
continued moderate exercise:lipids may provide 80% of
energy
Lipids and Exercise Intensity
intensity- lipid utilization remains same- blood glucose & muscle
glycogen
@ 25% or 85% of max. exercise lipid utilization remains same
Lipids and Exercise Intensity
trained individuals - more efficient - mobilizing FFA- utilizing FFA
conserve glycogen reserves
Lipids and Exercise Intensity
0
50
100
150
200
250
Trained Untrained
Plasma FFA
Triglyceride
Glycogen
Blood Glucose
Tis
sue
O2 u
ptak
e (m
L/k
g. min
)
Lipid
Saltin B, Astrand PO. Free fatty acids and exercise. Am. J. Clin. Nutr., 57(suppl): 752S, 1993)
Training Effect
enzymes responsible for producing energy
improved transport of FFA thru membranes
altered transport of FFA ( proteins & enzymes)
proliferation of capillaries (vascularization)
Proteins
Sources:- eggs*, milk, meat, fish, poultry
- 67% from animals- cholesterol- saturated fat
- animal sources more complete- vary plant sources to achieve
variety
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
Amino Acid Supplementation
has NOT demonstrated:
increased muscle mass
improved muscular strength, power, or endurance
Protein in the Body
found in:- blood plasma- visceral tissue- muscle
important functional & structural roles no stores
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
Role of Amino Acids/Protein
blood plasma proteins-hemoglobin
genetic material (RNA/DNA) buffering muscle – actin, myosin
Protein Metabolism
catabolized @ rest for energy (2-5%)
deaminized first urea urine
excessive protein catabolism excessive H20 loss
Protein Utilization during Exercise
0
200
400
600
800
1000
1200
1400
1600
Rest High CHO Low CHO
Sw
eat u
rea
nitr
ogen
(m
g/h)
Lemon PWR, Nagel F. Effects of exercise on protein and amino acid metabolism. Med. Sci. Sports Exerc., 13: 141, 1981.
Protein Utilization during Exercise
Ala
nine
out
put f
rom
legs
(m
M/m
in.)
Felig P, Wahren J. Amino acid metabolism in exercising. J. Clin. Invest. 50: 2703, 1971.
0
20
40
60
80
100
120
140
160
180
Rest Mild Moderate Severe
Protein Metabolism
Nitrogen balance nitrogen (protein) in = nitrogen outPositive nitrogen balance nitrogen in > nitrogen out children pregnancy recovery 20 to resistance training
Protein Metabolism
Negative nitrogen balance- nitrogen in < nitrogen out- protein used as 10 energy
source - starvation – dietary
implications loss of LBM