Energy production, Expenditure and Transfer

1. Energy Production,
Expenditure and Transfer
Presented by Moderator:
Arsha Raj P R Dr. V. Krishna Reddy, Ph.D.
Mini Uniyal Associate Professor,
MPT 1st year (Sports medicine) Galgotias University

2. Content
• Energy transfer in cells during exercise
• Oxygen metabolism and transfer during metabolism
• Oxygen transport in blood
• Oxygen deficit, oxygen debt
• Oxygen measurement, oxygen during exercise , oxygen during recovery
• Energy release from carbohydrates, lipids and protein
• BMR- during rest, at activity
• Energy expenditure during activity
• Short term and long term energy systems

3. Energy transfer in cells during exercise
• The continual supply of ATP to the fundamental cellular processes that
underpin skeletal muscle contraction during exercise is essential for sports
performance in events lasting seconds to several hours. Because the muscle
stores of ATP are small, metabolic pathways must be activated to maintain
the required rates of ATP resynthesize.

5. • Adenosine Triphosphate (ATP):
• ATP is a high-energy compound crucial for both rest and exercise.
• It consists of adenine, ribose (adenosine), and three phosphate groups.
• Cells don’t directly obtain energy from food; instead, it must be broken
down into ATP.
• Hydrolysis of ATP (cleavage of a phosphate bond) releases energy:
• ATP + H₂O → ADP + Pi + energy

6. Energy Stores:
• Carbohydrates:
• Rapidly available energy source.
• Converted to glucose, which serves various purposes:
• Direct energy for cells.
• Stored as glycogen in muscles and liver.
• Converted to fat for storage.
• Provides carbon skeletons for non-essential amino acid synthesis.
• Key conversions:
• Glucogenesis: Glucose → Glycogen.
• Gluconeogenesis: Protein → Glucose.
• Glycogenolysis: Glycogen → Glucose.

7. • Fats:
• Predominantly stored as adipose tissue.
• Supplies about 50% of energy during light and moderate exercise.
• Becomes the primary energy source (over 70%) during prolonged
exercise.
• Requires more oxygen for aerobic breakdown.
• Fatty acids are released from triacylglycerol in fat storage sites and
delivered to muscle tissue via the circulation.
• Proteins:
• Can only provide 5% to 10% of energy during sustained exercise.
• Amino acids (AA) are protein subunits.
• Protein is broken down into AA, which can then be converted into
glucose for energy.

8. Energy Systems:
• Phosphagen System (Immediate):
• Relies on stored ATP and creatine phosphate.
• Provides immediate energy during transitions (rest to exercise, intensity
changes).
• Glycolysis (Anaerobic):
• Preferred system for exercise work.
• Fast process occurring within the cell’s sarcoplasm.
• Utilizes glucose.
• Oxidative System (Aerobic):
• Predominant ATP generation during most movements.
• Occurs in mitochondria using oxygen, ADP, Pi, and reducing equivalents from
food.
• Known as oxidative phosphorylation.

9. Oxygen metabolism and transfer during
metabolism
• Oxygen plays a crucial role in metabolism, particularly in the process
of cellular respiration.
Electron Transport Chain (ETC): Within the mitochondrial inner
membrane, oxygen acts as the terminal electron acceptor at the end of the
ETC. This chain of events is part of cellular respiration, where electrons are
transferred step by step. The final step occurs when these electrons are
delivered to oxygen molecules in the mitochondrial matrix.

10. • Oxidative Phosphorylation: As electrons move through the ETC, they
create a flow of protons across the mitochondrial membrane. This proton
gradient generates energy. Oxygen’s role is pivotal here: it combines with
these electrons to form water (H₂O). Simultaneously, the excess protons
drive the enzyme ATP synthase, resulting in the synthesis of adenosine
triphosphate (ATP)—the energy currency for all active metabolic processes.

11. • Anaerobic Metabolism: While oxygen is essential for efficient energy
production, some eukaryotes can perform catabolic processes without
oxygen (aerobic metabolism). This alternative process, known
as fermentation, occurs in the absence of oxygen.
• Oxygen’s involvement in metabolism is multifaceted: it facilitates the
transfer of electrons, drives ATP synthesis, and ensures the continuation of
life-sustaining energy cycles. Without oxygen, these processes would come
to a halt, emphasizing its critical role in our existence.

13. Oxygen transport in blood
• Oxygen, a vital molecule in the human body, plays a crucial role in energy production
through the electron transport chain.
• Hemoglobin: The primary carrier of oxygen in blood is hemoglobin, a protein found in
red blood cells. Each hemoglobin molecule can bind up to four oxygen molecules. When
blood passes through the lungs, oxygen molecules attach to hemoglobin,
forming oxyhemoglobin.
• Dissolved Oxygen: A small portion of oxygen (approximately 2%) directly dissolves in
the plasma. This dissolved oxygen contributes to the overall oxygen content in the blood.

14. • Hemoglobin Structure: Hemoglobin consists of four subunits—two
alpha and two beta subunits. Each subunit contains a heme group with an
iron atom at its center. Oxygen binds reversibly to these iron atoms.
• Binding Mechanism: As oxygen molecules bind to hemoglobin, a
conformational change occurs in the globin chain structure. This change
affects the affinity of the remaining subunits for oxygen. Deoxygenated
hemoglobin exists in a tense (T) conformation, with low oxygen affinity. As
oxygen binds, hemoglobin transitions to a relaxed state, allowing further
oxygen molecules to bind more easily.

15. Clinical Measurements:
• Partial Pressure of Oxygen (PO₂): Reflects the amount of oxygen
dissolved directly in the plasma.
• Oxygen Saturation (SO₂): Indicates the proportion of hemoglobin with
oxygen bound to it.

17. Oxygen deficit, Oxygen debt
• Oxygen debt refers to extra oxygen (compared with its usual oxygen intake
at rest) an organism consumes after a period of strenuous physical activity,
while oxygen deficit refers to the difference between oxygen uptake in the
early stages of exercise and the oxygen uptake in a similar duration in a
steady state of exercise.

18. Oxygen Debt
• Definition: Oxygen debt refers to the extra volume of oxygen needed by
the body after exercise to restore it to a normal state.
• Cause: During strenuous physical activity, the body experiences an oxygen
deficiency. This deficiency occurs because anaerobic conditions lead to the
formation of lactic acid in muscles from glucose.
• Also Known As: Excess post-exercise oxygen consumption (EPOC).

19. • Purpose: The extra oxygen consumed after exercise helps:
• Reconvert lactic acid buildup in muscles.
• Restore hormonal balance.
• Facilitate cellular repair.
• Replenish fuel stores.
• Support innervation and anabolism.
• Replenish the phosphagen system.
• Enable aerobic respiration and ATP production.

20. Oxygen Deficit
• Definition: Oxygen deficit represents the difference between the
body’s oxygen intake during the early stages of exercise and the oxygen
intake during the steady state of exercise.
• Scenario: Oxygen deficit occurs when the body’s oxygen
consumption exceeds the intake of oxygen.
• Replenishment: The body works to replenish the oxygen deficiency
during the recovery period. As a result, oxygen consumption increases
during this phase.

21. • Example: Suppose a person requires 1.5 liters of oxygen to perform a
physical function. However, the actual intake during an hour of exercise is
only 1.0 liter. In this case, the oxygen deficit is 0.5 liters per hour. If the total
exercise lasts for four hours, the cumulative oxygen deficit would be 2 liters.

22. Oxygen measurement, oxygen during
exercise , oxygen during recovery
• Oxygen Measurement:
• Pulse Oximeters: These devices are ideal for measuring oxygen levels
and pulse rate both before and after exercise. While measuring during
active movement is not recommended (since pulse oximeters are less
accurate while the user is moving), they can provide valuable insights
during recovery and even continuous monitoring during sleep, which is
crucial for optimal recovery1.

23. • Oxygen During Exercise:
• EPOC (Excess Post-Exercise Oxygen Consumption): EPOC is the
physiological measure of training load. Essentially, it quantifies the excess
oxygen consumed during post-exercise recovery compared to resting oxygen
consumption. The amount of EPOC achieved during exercise is proportionate
to the training load and recovery required2.
• Oxygen Deficit: During strenuous exercise, the body experiences an oxygen
deficit. This deficit triggers a subsequent recovery period during which the
body works to replenish oxygen levels. The recovery time does not necessarily
depend on the intensity of the maximum load.

24. • Oxygen During Recovery:
• After exercise, the breathing rate and tidal volume remain elevated during the
recovery period. This elevation serves several purposes:
• Remove Excess Carbon Dioxide: Elevated breathing helps remove excess
carbon dioxide.
• Repay Oxygen Debt: The body repays its oxygen debt incurred during exercise.
• Cool Down: Elevated breathing also aids in cooling down the body.
• Gradually, as the body’s need for oxygen returns to resting levels, both respiratory
rate and tidal volume slowly return to their resting values

25. Energy Release From Carbohydrates
• Carbohydrates, or carbs, are sugar molecules. Along with proteins and fats, carbohydrates
are one of three main nutrients found in foods and drinks.
• Your body breaks down carbohydrates into glucose. Glucose, or blood sugar, is the main
source of energy for your body’s cells, tissues, and organs
• Simple carbs are easily digested while complex carbs take time • produce 4kcal/G energy
approximately
• Glycolysis - the process of breaking down A glucose molecule into two pyruvate
molecules, while storing energy released during this process as adenosine triphosphate
(ATP) and nicotinamide adenine dinucleotide (NADH).

26. • Gluconeogenesis - is a metabolic pathway that results in the generation of
glucose from certain non-carbohydrate carbon substrates. It is A ubiquitous
process, present in plants, animals, fungi, bacteria, and other microorganisms
• Glycogenolysis - refers to the breakdown of glycogen . In the liver, muscles,
and the kidney, this process occurs to provide glucose when necessary . A single
glucose molecule is cleaved from A branch of glycogen, and is transformed into
glucose-1-phosphate during this process. This molecule can then be converted to
glucose-6-phosphate, an intermediate in the glycolysis pathway.
• Glycogenesis -glycogenesis refers to the process of synthesizing glycogen

27. • The cofactors NADH+ and fad are sometimes reduced during this process to
form NADH and FADH2, which drive the creation of ATP in other processes.
Amolecule of NADH can produce 1.5–2.5 molecules of ATP, whereas A
molecule of FADH2yields 1.5 molecules of ATP
• The complete breakdown of one molecule of glucose by aerobic respiration
(I.E. Involving glycolysis, the citric-acid cycle and oxidative phosphorylation,
the last providing the most energy) is usually about 30–32 molecules of ATP.
Oxidation of one gram of carbohydrate yields approximately 4 kcal of
energy

28. Energy Release From Lipids
• Lipid metabolism begins in the intestine where ingested triglycerides are broken
down into smaller chain fatty acids and subsequently into monoglyceride
molecules by pancreatic lipases, enzymes that break down fats after they are
emulsified by bile salts. When food reaches the small intestine in the form of
chyme, A digestive hormone called cholecystokinin (CCK) is released by intestinal
cells in the intestinal mucosa
• The pancreatic lipases and bile salts break down triglycerides into free fatty acids
• These triglycerides are packaged along with cholesterol molecules in phospholipid
vesicles called chylomicrons . Produce approximately 9kcal/G energy

29. Lipolysis
• To obtain energy from fat, triglycerides must first be broken down by
hydrolysis into their two principal components, fatty acids and glycerol. This
process, called lipolysis, takes place in the cytoplasm. The resulting fatty
acids are oxidized by β-oxidation into acetyl coa, which is used by the krebs
cycle one triglyceride molecule yields three fatty acid molecules with as
much as 16 or more carbons in each one, fat molecules yield more energy
than carbohydrates and are an important source of energy for the human
body.

30. • The breakdown of fatty acids, called fatty acid oxidation or beta (β)-
oxidation, begins in the cytoplasm, where fatty acids are converted into
fatty acyl COA molecules. This fatty acyl COA combines with carnitine to
create A fatty acyl carnitine molecule, which helps to transport the fatty
acid across the mitochondrial membrane.
• Once inside the mitochondrial matrix, the fatty acyl carnitine molecule is
converted back into fatty acyl COA and then into acetyl COA. The newly
formed acetyl COA enters the Krebs cycle and is used to produce ATP in the
same way as acetyl COA derived from pyruvate.

31. Lipogenesis
• When glucose levels are plentiful, the excess acetyl COA generated by
glycolysis can be converted into fatty acids, triglycerides, cholesterol,
steroids, and bile salts.

32. Energy Release From Proteins
• 4kcal/G
• Digestion begins in stomach where pepsin and HCL breaks it into peptides by
denaturing it
• Pancreas releases most of the digestive enzymes, including the proteases trypsin,
chymotrypsin, and elastase, which break complex proteins into smaller individual
amino acids, which are then transported across the intestinal mucosa to be used
to create new proteins, or to be converted into fats or acetyl COA and used in the
Krebs cycle.

33. • Trypsin and chymotrypsin break down large proteins into smaller peptides,
a process called proteolysis.
• If amino acids exist in excess, the body has no capacity or mechanism for
their storage; thus, they are converted into glucose or ketones, or they are
decomposed. Amino acid decomposition results in hydrocarbons and
nitrogenous waste.

34. BMR
• Basal metabolic rate (BMR) is the rate of energy expenditure per unit time.
• It is reported in energy units per unit time ranging from watt (joule/second) to ml o2 /min or
joule per hour per kg body mass j/(h·kg)
• You burn calories even when resting through basic life-sustaining functions like breathing,
circulation, nutrient processing, and cell production. This is known as basal metabolic rate
(BMR).
• Basal metabolic rate (BMR) vs resting metabolic rate (RMR)
• Basal metabolic rate (BMR) is often used interchangeably with resting metabolic rate (RMR).
• While BMR is the minimum number of calories required for basic functions at rest, RMR — also
called resting energy expenditure (REE) — is the number of calories that your body actually
burns while it’s at rest.

35. • Although BMR and RMR slightly differ, your RMR should be an accurate estimate
of your BMR. The two values tend to vary by about 10%
• How to estimate your BMR one popular way to estimate BMR is through the
Harris-benedict formula, which takes into account weight, height, age, and sex.
• Females assigned at birth (FAABS)
• BMR = 655 + (9.6 X weight in kg) + (1.8 X height in cm) – (4.7 X age in years)
• Males assigned at birth (MAABS)
• 66 + (13.7 X weight in kg) + (5 X height in cm) – (6.8 X age in years)

36. Factors determining BMR
• Sex
• Weight
• Height
• Age
• Ethnicity
• Weight history
• Body composition
• Genetic factors

37. • Helpful in determining the exercise and calorie intake by:-
• • sedentary: if you get minimal or no exercise, multiply your BMR by 1.2.
• Lightly active: if you exercise lightly one to three days a week, multiply your BMR by 1.375.
• Moderately active: if you exercise moderately three to five days a week, multiply your BMR
by 1.55.
• Very active: if you engage in hard exercise six to seven days a week, multiply your BMR by
1.725.
• Extra active: if you engage in very hard exercise six to seven days a week or have a physical
job, multiply your BMR by 1.9.

38. Energy Expenditure During Activity
• The food eaten by us is broken down into calories which is utilized for body functions or is
stored for later.
• Energy expenditure of activity (EEA) is the amount of energy needed to fuel body
movement as it occurs in activities of daily living, including exercise. Muscle tissue
consumes approximately 20% of this energy at rest, but during vigorous exercise, the rate
of energy consumption by muscle tissue may go up 50 times or more.
• Physical activity can have a dramatic impact on a person’s daily energy expenditure. During
heavy physical exertion (vigorous activity), the muscles may burn as many as 1200 cal per
hour in A very fit individual. An unfit person may only be able to expend 200 cal per hour.
Involuntary movements such as fidgeting and posture control (called neat: non-exercise
activity of thermogenesis) also contribute to EEA.

39. Short Term And Long Term Energy
Systems
• The human body needs energy to function, and food is the fuel source for energy. The
body has the ability to convert foods that are consumed into an important form of
chemical energy, called adenosine triphosphate (atp). ATP is used to power all manner of
cellular processes in the body, and only A small amount is stored within the body. In order
to keep the body's functions going all the time, ATP must be continually generated.
• Carbohydrates are used for short term energy needs whereas fats are used for long term
energy needs.
• Proteins are also a supplier of energy but that is used in muscle building

40. Types
• Immediate energy system/ creatine phosphate system-this system uses creatine
phosphate (cp) and has a very rapid rate of atp production. The creatine phosphate is used
to reconstitute atp after it’s broken down to release its energy. The total amount of cp and
atp stored in muscles is small, so there is limited energy available for muscular contraction.
It is, however, instantaneously available and is essential at the onset of activity, as well as
during short-term high-intensity activities lasting about 1 to 30 seconds in duration, such
as sprinting, weight-lifting or throwing A ball.
• Short term energy system/lactic acid system- anaerobic glycolysis does not require oxygen
and uses the energy contained in glucose for the formation of ATP.
• This pathway occurs within the cytoplasm and breaks glucose down into a simpler
component called pyruvate.

41. • As an intermediate pathway between the phosphagen and aerobic system, anaerobic
glycolysis can produce ATP quite rapidly for use during activities requiring large bursts of
energy over somewhat longer periods of time (30 seconds to three minutes max, or during
endurance activities prior to steady state being achieved).
• Long term energy system/aerobic energy system- this pathway requires oxygen to produce
ATP, because carbohydrates and fats are only burned in the presence of oxygen. This
pathway occurs in the mitochondria of the cell and is used for activities requiring sustained
energy production. Aerobic glycolysis has a slow rate of atp production and is
predominantly utilized during longer-duration, lower-intensity activities after the
phosphagen and anaerobic systems have fatigued.

42. THANK YOU