2. Energy
Energy is the capacity to
perform work
Energy can come from a
number of different forms
- Chemical
- Electrical
- Electromagnetic
- Thermal
- Mechanical
- Nuclear
3. Energy
Law of “Thermodynamics”
states that all forms of energy
are interchangeable.
Energy is never lost or newly
created but always changing.
Energy originates from the sun
as light energy and is converted.
- Ultimately stored in plants
» Carbohydrates
» Fats
» Proteins
4. Energy for Cellular
Activity
Energy sources
- carbohydrates - glucose =
(C6H12O6)
- fats - fatty acids = (C16H18O2)
- proteins - amino acids + nitrogen
The amount of energy released
in a biological reaction is
calculated from the amount of
heat produced.
1 Kilocalorie = the amount of
heat energy needed to raise 1kg
of water 1 degree Celcius.
5. Energy Sources
The energy in food moleculear
bonds is chemically released
within our cells then stored in
the form of ATP bonds.
The formation of ATP provides
the cells with a high-energy
compound for storing and
conserving energy.
6. Carhohydrates
Come in many kinds of foods.
Are converted to glucose, a
monosacharide (one-unit sugar)
and transported by the blood to
all body tissues.
One gram yields about 4 kcal.
Are stored as glycogen in your
muscles (cytoplasm) and liver
(up to 2,000 kcal)
Without adequate carbohydrate
intake, the muscles and liver
stores can be depleted very
quickly.
7. Fat
Comes in many foods
Broken down into free fatty acids
which can be used to form ATP.
A gram of fat yields about 9 kcal.
Fat provides a sizable amount of
energy (70,000 kcal) during
prolonged, less intense exercise.
Fat is stored intramuscularly or
subcutaneously
Fat is more difficult to break down
and therefore it is less accessible for
cellular metabolism.
8. Protein
Can only supply up to 5% to
10% of the energy needed to
sustain prolonged exercise
Amino acids are broken down
into glucose (gluconeogenesis).
A gram of protein yields about
4 kcal.
9. Bioenergetics: ATP
Production
By the ATP-PCr system
- anaerobic (fig. 5.3, 5.4)
- simplest energy system
- 1 mole PCr = 1 mole of ATP
- 1 ATP = 7.6 kcal
By the glycolytic system
- anaerobic (fig. 5.6)
- 1mole glycogen = 3moles of ATP
By the oxidative system
- aerobic (fig. 5.7, 5.8)
- energy yield = 39 moles of ATP
10. ATP-PCr System
The simplest of the energy
systems
Energy released by the break-
down of Creatine Phosphate
(PCr), facilitated by the enzyme
creatine kinase (CK), rebuilds
ATP from ADP.
This process is rapid
Does not require oxygen (O2)
and is therefore anaerobic.
Can only sustain maximum
muscle work for 3-15 seconds.
11. The Glycolytic System
Involves the breakdown (lysis)
of glucose via special glycolytic
enzymes.
Glucose accounts for about 99%
of all sugars circulating in the
blood.
Glucose comes from the
digestion of carbohydrates and
the breakdown of glycogen
during glycogenolysis.
Glycogen is synthesized from
glucose during glycogenisis.
12. The Glycolytic System
Glucose and glycogen needs to
be converted to glucose-6-
phosphate before it can be used
for energy. For glucose this
process takes 1 ATP.
Glycolysis ultimately produces
pyruvic acid which is then
converted to lactic acid in the
absence of oxygen.
Gycolysis requires 12
enzymatic reactions to form
lactic acid which occur within
the cells cytoplasm
13. The Glycolytic System
1 glycogen = 3 ATP
1 glucose = 2 ATP
Causes lactic acid accumulation
in the muscles
- This acidification discourages
glycolysis
- Decreases the muscle fibers’
calcium binding capacity and
therefore impedes muscle
contraction.
14. The Oxidative System
(Carbohydrate)
Glycolysis:
- pyruvic acid is oxidized into
acetyl coenzyme A
- 2 or 3 ATP are formed
Krebs Cycle:
- acetyl CoA = (2ATP + H + C)
- H accepted by NAD & FAD
Electron Transport Chain:
- the splitting of H electrons and
protons provides energy to perform
oxidative phosphorylation
- (ADP+P=ATP) + H2O + CO2
- glycogen = 39 moles of ATP
15. The Oxidative System
(Carbohydrate)
Cellular Respiration: energy
production in the presence of
oxygen.
Occurs in the mitochondria
adjacent to the myofibrils and
within the sarcoplasm.
High energy yields (39 ATP)
which are used during aerobic
events.
16. The Oxidative System
(Fat)
Lipolysis: Triglycerides are
broken down into glycerol and
fatty acids by lipases.
Beta Oxidation: fatty acids are
broken down into units of acetic
acid and converted to acetyl-
CoA
Krebs Cycle:
Electron Transport Chain:
1mole of palmitic acid = 129
moles of ATP
17. Protein Metabolism
Gluconeogenesis: some amino
acids can be converted into
glucose, pyruvate acid, or
acetyl CoA
ATP is spent in this process
Biproducts include other amino
acids or nitrogen which is
excreted in urine.
Energy from protein
metabolism is ignored
18. The Oxidative Capacity
of Muscle
Enzyme Activity
Muscle Fiber Types
- slow twitch (type 1)
» Greater oxidative capacity
- fast twitch A (type 2a)
- fast twitch B (type 2b)
Endurance Training
- enhances mitochondria density
- enhances enzymes for B oxidation
Cardiovascular Function
- improved rate/depth of respiration
- increased gas exchange & H.R.
- Max VO2
19. Measuring Energy Use
During Exercise
Direct Calorimetry
- Measures body heat production
Indirect Calorimetry
- amount of O2 & CO2 exchanged
- respiratory exchange ratio (RER)
» measures food source
Isotopic Measurements
- Isotopes are elements with an
atypical atomic weight
- Isotopes are traced to determine
metabolism
- measures CO2 produced which is
converted to energy expended
Daily Caloric Computation
- is a highly estimated computation
20. Estimates of Anaerobic
Effort
Post-Exercise O2 Consumption
- oxygen deficit
- steady state
- EPOC
Lactate Threshold
- The point at which the blood
lactate appears to increase above
resting levels.
- A clear break point when the
onset of blood lactate accumulates
(OBLA)
- when expressed as a % of VO2
max is a good indication of
tolerance (pace).
21. Energy Expenditure
Basal Metabolic Rate: measured
in O2 use per min. at rest
- how is it affected?
» Fat free mass
» Body surface area = heat loss
» Age
» Body temperature
» Stress
» Hormone levels
VO2 Max (aerobic capacity)
- how is it affected?
» Oxygen consumption increases with
increased intensity of exercise
» VO2 Max plateaus
» To perform at a higher % of VO2
Max reflects a higher lactate
threshold
22. Energy Expenditure
Economy Of Effort
Factors of Endurance Success
- high VO2 max
- high lactate threshold or OBLA
- high economy of effort
- high percentage of ST muscle
Range of Total Daily Caloric
Expenditure is Variable With
- Activity level
- Age
- Sex
- Size
- Weight
- Body Composition
23. Causes of Fatigue
Decreased Energy
- ATP-PCr
» Phosphocreatine depletion
» warm-up & pacing decreases fatigue
» “hitting the wall” = no energy
- glycolysis
» Glycogen depletion in used muscles
» depletion in certain muscle fiber types
» depletion of blood glucose
- oxidation
» a lack of O2 increases lactic acidlactic acid
bicarbonate & cool down
» a causitive factor of muscle strains
Accumulation of Metabolic Bi-
products (acidosis).
24. Causes of Fatigue
Neuromoscular Fatigue
- decreased nerve transmission
» Depleted acetyl Co A
» Sarcolemma membrane threshold
might increase
» Decreased potassium needed for
nerve transmission along the
sarcolemma
» Calcium rentention within the
sarcoplasmic reticulum.
- fatigue may be psychological and
therefore terminate exercise
before the muscles are
physiologically exhausted
» verbal encouragement
» fight or flight mechanism
» perceived discomfort preceeds
muscle physiological limitations
Delayed Onset Muscle Soreness
Editor's Notes
The “Law of Thermodynamics”: All forms of energy are interchangable, never lost or newly created,
ultimately becoming heat.
- 60%-70% of the total energy of the human body is degraded to heat
Energy Sources
Carbohydrates: are ultimately converted to glucose
Fats: the body stores much more fat (70,000 calories) than it does carbohydrates
Protein: gluconeogenesis is the conversion of protein or fat to glucose
ATP-PCr: is the simplest of the energy systems
- Creatine Kinase is a catalyst which facilitates the release of energy from PCr
- at exhaustion both ATP and PCr levels are quite low
- Your ATP and PCr stores can sustain your muscles energy for only 3-15 second sprint
- 1mole of PCr = 1mole of ATP
Glycolysis:
- glucose accounts for about 99% of all sugars in the blood
- glycogen is broken down to glucose-1-phosphate through glycogenolysis
- then it must be converted to glucose-6-phosphate
- glycolytic enzymes ultimately produces pyruvic acid
- 1mole of glycogen = 3moles of ATP 1mole of glucose = 2moles of ATP
- without oxygen lactic acid is formed
Glycolysis:
- oxygen only determines the fate of the by product (pyruvic acid)
Krebs Cycle::
- a complete series of chemical reactions (catalyzed by enzymes) that permits the complete
oxidation of acetyl CoA.
- 2ATP are formed
Electron Trasport System:
- Hydrogen combines with NAD and FAD which carries it to the electron transport chain
- Hydrogen atoms split into protons and electrons
Lipolysis::
- phospholipids and cholesterol are fats but are not considered major energy sources
- triglycerides are considered major energy sources
B Oxidation:
- energy is used to break down (catabolize) triglycerides within the mitochondria
- free fatty acids become 2-carbon units of acetic acid
Krebs Cycle:
- H is generated and is transported to the electron transport chain
Electron Transport Chain:
- a 16 carbon fatty acid produces18 moles of acetic acid which produces 129 moles of ATP
- biproducts include H2O, and CO2
Complete combustion of fatty acids requires more oxygen because it contains considerably more carbon
Enzyme Activity:
- increased enzyme activity equals increased oxygen consumption
- endurance athletes muscles have 2 to 4 times the oxydative activity than untrained men
Muscle Fiber Type:
- Type 1
- more mitochondria and oxidative enzymes
- red in color - high capillary density
- slow to react
- Type 2a
- produce some force
- pink in color - moderate capillary density (some aerobic capabilities)
- Type 2b
- produce great force
- white in color - fatigue easily
Direct Calorimetry:
- an insulated airtight chamber is used to measure body heat
Indirect Calorimetry:
- calorie expenditure can be estimated by measuring your respiratory gasses
- Respiratory Exchange Ratio = CO2 / O2
Daily Calorie Computations: performed in class
Post-Exercise Oxygen consumption:
- Oxygen Deficit: the difference between the oxygen required for a given rate of work
and teh oxygen actually consumed
- Steady State: is when the oxygen demand is equal to the oxygen consumed
- Excess Post-Exercise Oxygen Consumption: is the increased oxygen consumption over
resting levels
1.) required to rebuild ATP and PCr
2.) removal of lactate from the tissues ---- [cool down]
3.) replenish oxygen stores (hemoglogin)
4.) required to decrease CO2 levels in the tissues and blood
Lactate Threshold: the point at which blood lactate begins to accumulazte above resting levels during exercise of increasing intensity
- thought to reflect the interaction of the aerobic and anaerobic energy systems
- a lactate threshold at 80% of VO2 max suggests a greater tolerance than at 60% VO2 max
Basal Metabolic Rate: how is it affected?
- fat free mass, surface area, age, body temperature, stress, hormones
- average daily metabolic rate is 1,800 to 3,000 kcal.
VO2 max: how is it affected?
- type of exercise performed
- body composition
- blood hemoglobin
- training
Economy of Effort: this is the coaches job
