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1. ENERGY FOR PHYSICALACTIVITY

2. ENERGY VALUE OF FOOD
• A calorie or kilocalorie is a measure of heat that express a
foods energy value.
• One calorie expresses the quantity of heat necessary to raise
the temperature of l kg of water by 1degree celsius
• An instrument for measuring heat output of the body or the
energy value of foods is called a Calorimeter.
Bomb calorimeter
• Measures total energy value of food.
• It is a type of direct calorimetry.
• Sealed chamber charged with oxygen. Increase in water
temperature directly reflects the heat released during a food’s
oxidation
• Heat of combustion.

3. Heat of combustion of a substance is defined as “the change in
enthalpy of a system when one mole of the substance is
completely burnt in excess of air or oxygen”.
• It is denoted by ( ΔH ∘ C)
• Heat of combustion for :
1g of Carbohydrate - 4.2 kcal
1g of fat - 9.45 kcal
1g of protein - 5.65 kcal.
NET ENERGY VALUE :
 Actual energy available to the body
 Coefficient of digestibility is affected by dietary fiber
 Atwater general factors

4. • The Atwater system is used in the food industry to determine
the total calorific value of food.
• Atwater 4-9-4 kcal rule generally proves useful to estimate
the intake of food energy and content of the daily diet.
 4kcal per gram for dietary carbohydrate
 9kcal per gram for dietary lipid
 4 kcal per gram for dietary protein

5. INTRODUCTION TO ENERGY TRANSFER
energy is defined as the ability to do work

6. • Bio energetics refers to the flow and exchange of energy
within a living system
• FIRST LAW OF THERMODYNAMICS :
It is also known as law of
conservation of energy . Energy can not be created or
destroyed, but is transformed from one form to another
without being depleted.
• SECOND LAW OF THERMODYNAMICS :
It is also known as law of
degradation of energy. The transfer of potential energy to
kinetic energy in any spontaneous process always proceeds in
a direction that decreases the capacity to do work

8. INTERCONVERSIONS OF ENERGY:
EXAMPLES OF ENERGY CONVERSIONS
 photosynthesis
captures energy to utilize as food and oxygen.
 Cellular respiration
part of the energy released becomes conserved
in compounds used for biologic process.

10. ENERGY TRANSFER IN THE BODY
• Energy transfer in human supports three forms of
biologic work :
• Mechanical work of muscle contraction
chemical energy → mechanical energy
• chemical work : neurotransmission and synthesize
cellular molecule
chemical energy → electrical energy
• Transport work:
 diffusion
 Active transport

11. THE RATE OF BIOENERGETICS :
• Enzymes act as biological catalysts
 Reduce required activation energy
 Accelerate the rate of chemical reactions
 Reaction rates depend on PH, temperature , availability of
substances
ENZYMES
 mode of action:
enzyme -substrate complex
COENZYMES:
 contains non protein, organic substances
 assist enzyme action by binding the substrate to the enzyme.
ENZYME INHIBITION:
 competitive inhibitors – bind to active site
 non competitive inhibitors- bind to a nonactive site

12. HYDROLYSIS AND CONDENSATION:
Hydrolysis reactions
 catabolism of complex organic molecules
 split chemical bonds by adding H+ and OH-
Condensation reactions
 anabolism of complex biomolecules.
 reverse of hydrolysis
OXIDATION AND REDOX REACTIONS:
OXIDATION – loss of electrons
transfer of oxygen, hydrogen,electrons
REDUCTION- gain of electrons
REDOX REACTIONS:
oxidation and reduction are coupled.

13. ENERGY RELEASED FROM FOOD

14.  Carbohydrates primary function -supplies energy for cellular
work.
 Maximal exercise - rapid energy release supplied by aerobic
metabolism.
 During light and moderate aerobic exercise, supplies
about one third of the body’s energy requirements.
 In prolonged aerobic exercise such as marathon running,
athletes often experience nutrient-related fatigue— muscle and
liver glycogen depletion.
 depleting glycogen reduces exercise power output.
ENERGY RELEASE FROM CARBOHYDRATES

15. ENERGY RELEASE FROM FAT
• Stored fat represents the source of potential energy. Adipocyte
is the Site of Fat Storage and Mobilization
• two sources:
triacylglycerol in fat cells (adipocytes)
intramuscular triacylglycerol
Three specific energy sources for fat catabolism include:
1. Triacylglycerols stored directly within the muscle fiber
2. Circulating in lipoprotein complexes become hydrolyzed
3. Mobilization
 utilizing fatty acids is lipolysis
 triacylglycerol splits into fatty acids and glycerol
 hormone sensitive lipase drives lipolysis.

16. ENERGY RELEASE FROM PROTEIN
DEAMINATION:
• nitrogen removal from amino acid
• occurs in liver and muscles
• enter citric acid cycle for oxidation.
TRANSAMINATION
• amine group transferred
Proteins as a fuel source :
 glucogenic may be used to form( pyruvate,oxaloacetate,
malate )
 ketogenic may be used to form (acetyl-CoA , Acetoacetate)

17. ENERGY TRANSFER DURING
EXERCISE

18. Immediate Energy
• The ATP-PCr System
• 5-8 seconds of maximum intensity exercise.
• Sprinting, football, weight lifting, baseball, volleyball,etc.
Short-Term Energy
• Lactic Acid System
• Maximal exercise between 60-180 seconds.
• high lactate concentration in maximal exercise
increases with specific sprint and power training.
• 400 m run,100 m swim, Multiple sprint sports ice
hockey, field hockey and soccer.

19. Lactate Accumulation
• Onset of blood lactate accumulation (OBLA)
• Blood lactate threshold (blood lactate is an Energy
Substrate for Gluconeogenesis in liver)
• Anaerobic threshold
Long Term Energy
• the Aerobic System
• Oxygen uptake (VO2).
• during the first minute of exercise.- Oxygen uptake
rises rapidly
• Between 3rd and 4th minute - a plateau is reached
and oxygen uptake remains stable.
• Functional capacities - to deliver adequate oxygen to
muscles

20. OXYGEN DEFICIT:
• The difference between oxygen uptake of the body during
early stages of exercise and during a similar duration in a
steady state of exercise aerobic metabolism occurs at onset of
exercise.
OXYGEN DEFICIT IN TRAINED AND UNTRAINED
• oxygen uptake during light and moderate intensity exercise
• trained reaches steady rate quicker
• Higher total energy consumption
• Less reliance on anaerobic gylcolysis
• Lower deficit in trained individual due to :
– Earlier aerobic ATP production
– Less lactate formation

21. Oxygen Debt
• The amount of extra oxygen the body needs
after exercise to react with the build up of
lactic acid and remove it from the cells.
Lactic acid + oxygen→ carbon dioxide +water
Lactic acid is poisonous (it also causes
muscle soreness) and needs to be removed.
• Breathing rate and heart rate remain high
after stopping exercise to “pay back” the
oxygen debt.

22. Maximum Oxygen Uptake
• The point when VO2 plateaus with additional workloads.
• Maximum VO2 indicates -aerobic resynthesis of ATP.
• above the max VO2 - accomplished by anaerobic
glycolysis.
Fast- and Slow-Twitch Fibers
Fast twitch fibers (ii) Slow twitch fibers (i)
Fast contraction speed Half as fast as fast twitch
High anaerobic capacity High aerobic capacity

23. Energy Spectrum
• Relative contribution of aerobic and anaerobic
energy during maximal physical effort.
• Intensity and duration determine the blend.
• Nutrient-related Fatigue : severe depletion
glycogen.
Oxygen consumption during Recovery
• Light aerobic exercise: steady-rate and small oxygen
deficit.
• Moderate to heavy: steady-rate and large oxygen deficit.

24. EXCESS POST- EXERCISE OXYGEN CONSUMPTION (EPOC)
• excess oxygen above the resting level is recovery.
• Oxygen deficit is smaller in moderate exercise
• Lactic acid accumulates in strenuous exercise
• Body temperature increased
Traditional Oxygen Debt Theory
• Alactacid oxygen debt: restoration of ATP& PCr
depleted during exercise, small portion to reload
muscle myoglobin and hemoglobin (fast).
• Lactacid oxygen debt: restoration of glycogen by
resynthesizing 80% HLa through gluconeogenesis (Cori
cycle) and to catabolize through pyruvic acid (Krebs cycle)
slower phase.

25. Lactate removal post – exercise
• mass action effect
• passive recovery (steady rate)
• active recovery( non steady rate)
Exercise Recovery Ratio
• 1:3 ratio overloads immediate energy system
• 1:2 ratio to train short-term glycolytic system
• 11 ratio to train long-term aerobic system

26. MEASUREMENT OF HUMAN ENERGY
EXPENDITURE

27. Direct calorimetry
 Airflow calorimeter
 Water flow calorimeter
 Gradient layer calorimeter
 Storage calorimetry
Indirect calorimetry
 closed circuit spirometry
 Open circuit spirometry
 Bag technique
 Computerized instrumentation
 Doubly layered water technique
 Respiratory exchange ratio
 Respiratory quotient

28. DIRECT CALORIMETRY :
• When body used energy to do work, heat is liberated
• Foodstuffs +O2 →ATP + Heat
↓cell work
Heat
• commonly heat production is measured in calories
1kcal=1000 calories
• This heat production can be measured directly in the Bomb
calorimeter.
• In this technique place human in air tight insulated chamber
with cold water flowing at constant rate , difference water
temperature in & out of chamber equals heat production.
•40% of the energy liberated from CHO/fat metabolism is used to
produce ATP & 60% is dissipated as heat

29.  Changes in water temperature relate directly to an individual’s
energy
 An increase of one degree Celsius by each kg (liter) of water
flowing equals one Kcal.
 CO2 is removed by chemical absorbents.

32. INDIRECT CALORIMETRY
It is a technique used to measure the metabolic rate of
an individual by indirectly measuring their oxygen
consumption (vo2) and carbon dioxide production
(vco2).
Foodstuffs + O2 & Heat + CO2 + H₂O
(indirect) (direct)
 body consumes oxygen to produce energy in the form
of ATP and this process results in the production of
carbon dioxide as a byproduct.
 Measurement of oxygen consumption is indirect, heat
not measured directly.

33. Closed circuit spirometry :
• spirometer filled with oxygen is used, Patient
breathes in and out
• Soda lime is used to absorb carbon dioxide.
Open circuit spirometry
• portable spirometry
• Spirometer is small, air volume is metered.
• It is used to measure concentrations of gases.
• Volume of carbon dioxide consumed per minute is
calculated as volume CO2 expired – volume CO2
inspired.

34. Doubly Labeled Water Technique
 Isotope-based method
 Doubly labeled water contains
Oxygen-18
Deuterium
 Isotopes consumed in a known volume of water
 Isotopes distribute throughout body fluids
 Hydrogen leaves body as 2H2O in sweat and urine .
 Oxygen leaves body as C18O2 orH2
18O
 Estimates total daily energy expenditure

35. Respiratory Exchange Ratio (RER)
• Ratio of CO2 produced to O2 consumed
• Calculation of RER is the same as RQ
Metabolic calculations
• Calculating energy expenditure during exercise
• Volume of air
• Concentration of O2 and CO2
Respiratory quotient
(RQ) is ratio of volume of carbon dioxide produced to volume
of oxygen consumed.
RQ = CO2 produced / O2 consumed

36. HUMAN ENERGY EXPENDITURE
DURING REST AND PHYSICAL ACTIVITY

37. BASAL METABOLIC RATE:
 BMR is the minimum amount of energy needed by the
body at rest in the fasting state
 measurements are taken by waking after 8 hours of sleep
and 12 hours of fasting
 Basal energy expenditure BEE or BMR is determined
largely by body size, body composition, Gender and age.
 Lower in females compared to males
 BMR is typically measured by indirect calorimetry
 Reflected in heat production
 Determined by oxygen consumption
Normalcy of BMR Value
 Δ BMR = (measured BMR - standard BMR) x100 ÷
standard BMR

38. RESTING METABOLIC RATE:
• The amount of energy used by a person in 24 hours when at
rest 3_4 hrs after a meal
• active metabolic processes & regulatory balance at rest
• accounts for 60-75% of TDEE
• physical activity 15-30%
• percent of the total daily calorie expenditure
Harris-Benedict equation : formula used to calculate BEE:
• Adult males: • BEE (kcal/day) = 66 + (13.7 x wt in kg) + (5 x ht in
cm) - (6.8 x age).
• Adult females: • BEE (kcal/kcal) = 655 + (9.6 x wt in kg) + (1.7 x
ht in cm) - (4.7 x age).

39. The thermic effect of food (TEF) :
• estimation from eating food, increase in energy expended
above RMR or BMR that results from digestion, absorption,
and storage of the food.
• It is also called the specific dynamic effect (SDE) of food
or the specific dynamic activity (SDA) of food
• The sum of the TEF and any increase in the metabolic rate due
to overeating is known as diet-induced thermogenesis
• 5-10 percent of the total calories burn in a day
effect of foods:
• Carbohydrate: 5–10%
• Fat: 0–5% is very easy to process &very little thermic effect
• Protein: 20–30% is hard to process & much larger thermic
effect
• Alcohol: 15–20%

40. FACTORS THAT AFFECT ENERGY
EXPENDITURE:
• physical activity
• dietary- induced thermogenesis
obligatory- digestive process
facultative- sympathetic process
• climate
hot or cold climate increase energy
expenditure
• pregnancy
increase BMR due to weight gain

41. ENERGY EXPENDITURE DURING
PHYSICALACTIVITY
CLASSIFICATION OF PHYSICAL ACTIVITIES BY ENERGY
EXPENDITURE
intensity
duration
physical activity ratio (PAR)
light work – 1-3xBMR
heavy work – 6-8 xBMR
maximal work – > 9 timesXBMR
THE MET:
MET = metabolic equivalent
• the amount of energy expended during exercise relative to
theenergy expenditure during rest
1 MET= 3.5 mL x Kg-1 x min -1

46. References
• McArdle, William D., Frank I. Katch, and Victor
L. Katch. 2000. Essentials of Exercise
Physiology 2nd ed. Image Collection. Lippincott
Williams Wilkins.
• Plowman, Sharon A. and Denise L. Smith. 1998.
Digital Image Archive for Exercise Physiology.
Allyn Bacon.