EXERCISE PHYSIOLOGY: AN
EXERCISE PHYSIOLOGY: AN OVERVIEWOVERVIEW
What is Exercise Physiology? What is Exercise Physiology?
Exercise Physiology is the study of theExercise Physiology is the study of the effects of exercise on the bodyeffects of exercise on the body..
Specifically, Exercise Physiology is concerned with theSpecifically, Exercise Physiology is concerned with the body’s responses &body’s responses &
adaptations to the stress of exercise
adaptations to the stress of exercise, ranging from the system level (e.g.,, ranging from the system level (e.g., cardiovascular system) to the subcellular level (e.g., production of ATP for energy). cardiovascular system) to the subcellular level (e.g., production of ATP for energy).
These modifications can beThese modifications can be short termshort term – that is lasting only for the duration of the– that is lasting only for the duration of the
activity/exercise – or
activity/exercise – or long termlong term – present as long as the activity is continued on a regular– present as long as the activity is continued on a regular basis.
basis.
Exercise physiologists are interested in both theExercise physiologists are interested in both the acuteacute (immediate) &(immediate) & chronicchronic (long-term)(long-term)
effects & adaptations
effects & adaptations of exercise on all aspects of body functioning.of exercise on all aspects of body functioning.
Acute adaptationsAcute adaptations – the changes in – the changes in human physiology that occur during exercise.human physiology that occur during exercise.
Chronic adaptationsChronic adaptations – the alterations in the structure & functions of the body that – the alterations in the structure & functions of the body that occur inoccur in
response to the regular completion of
response to the regular completion of exercise or physical activity.exercise or physical activity.
Exercise training – the repeated use of Exercise training – the repeated use of exercise to improve physical fitness.exercise to improve physical fitness.
Exercise Physiology Exercise Physiology
The study of how
The study of how body structurebody structure && functionfunction is altered by exposure to physical activityis altered by exposure to physical activity and exercise.
and exercise.
Sport Physiology Sport Physiology
The application of the concepts of
The application of the concepts of exercise physiologyexercise physiology to training athletes & enhancingto training athletes & enhancing sports performance.
sports performance. (Sport Physiology i(Sport Physiology is derived or s derived or evolved from Exercise evolved from Exercise Physiology)Physiology)
The Importance of exercise physiology to the practitioner The Importance of exercise physiology to the practitioner
Knowledge from exercise physiology is used to design effective fitness programs for peopleKnowledge from exercise physiology is used to design effective fitness programs for people of all ages, to guide the development & implementations of cardiac rehabilitation programs, of all ages, to guide the development & implementations of cardiac rehabilitation programs, to plan programs to help children & youths to incorporate physical activity into their life, to plan programs to help children & youths to incorporate physical activity into their life,
BASIC ENERGY SYSTEMS BASIC ENERGY SYSTEMS A. Energy
A. Energy
All plants & animals depend on energy All plants & animals depend on energy to sustain life.to sustain life.
Humans derive this energy from food.Humans derive this energy from food.
Many forms: chemical, electrical, electromagnetic, thermal, mechanical & nuclear.Many forms: chemical, electrical, electromagnetic, thermal, mechanical & nuclear.
All energy forms are interchangeable; e.g. chemical energy All energy forms are interchangeable; e.g. chemical energy used to create electricalused to create electrical
energy stored in battery. energy stored in battery.
Never lost or newly created – it undergoes steady degradation from one form toNever lost or newly created – it undergoes steady degradation from one form to
another, ultimately becoming heat. another, ultimately becoming heat.
60%-70% of the total energy in 60%-70% of the total energy in humans is degraded to heat.humans is degraded to heat.
1. Energy for Cellular Activity 1. Energy for Cellular Activity
All energy originates from the sun as light energy.All energy originates from the sun as light energy.
Chemical reactions in plants convert light into stored chemical Chemical reactions in plants convert light into stored chemical energy.energy.
Humans obtain energy by Humans obtain energy by eating plants, or animals that feed on plants.eating plants, or animals that feed on plants.
Energy is stored in food in the form ofEnergy is stored in food in the form of carbohydrate, fats & proteinscarbohydrate, fats & proteins..
Human cells can break down these 3 Human cells can break down these 3 basic food components to release the storedbasic food components to release the stored
energy. energy.
Energy Sources Energy Sources
Foods are composed of carbon, hydrogen, oxygen, & nitrogen (protein).Foods are composed of carbon, hydrogen, oxygen, & nitrogen (protein).
Molecular bonds in foods are weak & Molecular bonds in foods are weak & provide little energy when broken.provide little energy when broken.
Food is NOT used directly for cellular activity.Food is NOT used directly for cellular activity.
Energy in food molecules’ bonds chemically released within cells, Energy in food molecules’ bonds chemically released within cells, then stored in thethen stored in the
form of a
form of a high-energy compound calledhigh-energy compound called adenosine triphosphate (ATP).adenosine triphosphate (ATP).
At rest, energy that body needs is derived almost equally from the breakdown ofAt rest, energy that body needs is derived almost equally from the breakdown of
CHO & fats. CHO & fats.
Proteins provide little energy for cellular Proteins provide little energy for cellular function/activity.function/activity.
During mild to During mild to severe exercise, more CHO is used.severe exercise, more CHO is used.
In maximal, short-duration exercise, CHO is used exclusively to In maximal, short-duration exercise, CHO is used exclusively to produce ATP.produce ATP.
Carbohydrate (CHO) Carbohydrate (CHO)
Fats Fats
Fat provides 2 times more energy than CHO but less accessible for cellularFat provides 2 times more energy than CHO but less accessible for cellular
metabolism because it must first be reduced from its complex form (triglyceride) metabolism because it must first be reduced from its complex form (triglyceride) to its basic components: glycerol & free fatty acids (FFA).
to its basic components: glycerol & free fatty acids (FFA).
Only FFA are used to form ATP.Only FFA are used to form ATP.
Fat is a Fat is a good source of energy, can be good source of energy, can be stored exceeding 70,000 kcal of energy.stored exceeding 70,000 kcal of energy.
Protein Protein
Protein can be used as Protein can be used as energy source if convert into glucose.energy source if convert into glucose.
Protein converted into glucose Protein converted into glucose through gluconeogenesis.through gluconeogenesis.
In severe energy depletion (starvation), protein can be converted to FFA forIn severe energy depletion (starvation), protein can be converted to FFA for
cellular energy through lipogenesis. cellular energy through lipogenesis.
Protein can supply up to Protein can supply up to 5-10% of the energy needed to sustain prolonged exercise.5-10% of the energy needed to sustain prolonged exercise.
Protein can be used as energy source in basic form of amino acids.Protein can be used as energy source in basic form of amino acids.
Energy Yield Energy Yield
1 g of1 g of CHOCHO (C(C66HH1212OO66) yields) yields 44 kcal of energy.kcal of energy.
1 g of1 g of fatfat (C(C1616HH1818OO22) yields) yields 99 kcal of energy.kcal of energy.
1 g of1 g of proteinprotein(NH(NH22+ CO+ CO22H) yieldsH) yields 4.14.1kcal of energy.kcal of energy.
(Though 1 g of fat can generate 2.25 times as much as a similar amount of CHO,
(Though 1 g of fat can generate 2.25 times as much as a similar amount of CHO, it alsoit also takes substantially more oxygen to metabolize fat than CHO)
takes substantially more oxygen to metabolize fat than CHO)
B.
B. BioenergeticBioenergeticss
The chemical processes involved with the production of cellular ATP The chemical processes involved with the production of cellular ATP by convertingby converting
foodstuffs (i.e., carbohydrates, fats, proteins) into a biologically usable
foodstuffs (i.e., carbohydrates, fats, proteins) into a biologically usable form ofform of energy.
energy.
ATP Production ATP Production
An ATP molecule consists of An ATP molecule consists of adenosine (adenadenosine (adenine joined to ribose) combined with 3ine joined to ribose) combined with 3
inorganic phosphate (P
inorganic phosphate (Pii) groups.) groups.
When acted on by enzymeWhen acted on by enzyme ATPaseATPase (adenosine triphosphatase)(adenosine triphosphatase), the , the last phosphatelast phosphate
group splits away from the ATP molecule, rapidly releasing a large amount of energy group splits away from the ATP molecule, rapidly releasing a large amount of energy (7.6 kcal per mole of ATP). This reduces the ATP to ADP
(7.6 kcal per mole of ATP). This reduces the ATP to ADP & P& Pii.. ATPase
ATPase ATP
The process of storing energy by forming ATP from other chemical sources isThe process of storing energy by forming ATP from other chemical sources is
called
called phosphorylationphosphorylation..
Through various chemical reactions, a phosphate (PThrough various chemical reactions, a phosphate (Pii) groups is added to a ) groups is added to a relativelyrelatively
low-energy compound, ADP, converting it to ATP. low-energy compound, ADP, converting it to ATP.
ADP + P
ADP + Pii ATPATP
When these reactions occur without oxygen, the process is calledWhen these reactions occur without oxygen, the process is called anaerobicanaerobic
metabolism metabolism..
With the aid of OWith the aid of O22, the overall process is called, the overall process is called aerobic metabolismaerobic metabolism& the aerobic& the aerobic
conversion of ADP to ATP is
conversion of ADP to ATP is oxidativeoxidative phosphorylation.phosphorylation.
Cells generate ATP by 3 methods:Cells generate ATP by 3 methods:
1.
1. ATP-PC systemATP-PC system 2.
2. Glycolytic systemGlycolytic system 3.
3. Oxidative systemOxidative system
1. ATP-PC system
1. ATP-PC system: : (Anaerobic (Anaerobic ATP ATP Production)Production)
Formation of ATP by PC breakdown.Formation of ATP by PC breakdown.
The simplest of the energy system.The simplest of the energy system.
PhosphocreatinePhosphocreatine (PC) is a(PC) is a high-energy phosphate moleculehigh-energy phosphate molecule that store in the musclethat store in the muscle
cells. cells.
EnergyEnergy is released when PC isis released when PC is breakdown / separatebreakdown / separate toto PPii andand creatinecreatine by enzymeby enzyme
creatine kinase
creatine kinase (CK).(CK).
This energy is not used directly to accomplish cellular work.This energy is not used directly to accomplish cellular work.
EnergyEnergy released from the breakdown of PC is used to combinereleased from the breakdown of PC is used to combine PPii withwith ADPADP to formto form
ATP ATP..
This system isThis system is anaerobicanaerobic that functions tothat functions to maintainmaintain thethe ATPATP levels.levels.
1 mole of PC1 mole of PC will yieldwill yield 1 mole of ATP.1 mole of ATP.
Provides energy forProvides energy for short-termshort-termandandhigh-intensityhigh-intensityexercise that lasting aboutexercise that lasting about 3-
3-15 seconds 15 seconds..
2. Glycolytic system 2. Glycolytic system
Occurs in theOccurs in the sarcoplasmsarcoplasm of the muscle cells.of the muscle cells.
Use onlyUse only carbohydratecarbohydrateas the main source of fuel.as the main source of fuel.
InvolvesInvolves glycolysisglycolysisthethe breakdownbreakdown (lysis) of(lysis) of glucoseglucose or liveror liver glycogenglycogen totopyruvicpyruvic
acid
acid viavia glycolytic enzymesglycolytic enzymes..
Glycogen is synthesized from glucose by Glycogen is synthesized from glucose by a process called glycogenesis & stored ina process called glycogenesis & stored in
the liver or in muscle until needed. the liver or in muscle until needed.
Before either glucose 0r glycogen can be used to generate energy, they must beBefore either glucose 0r glycogen can be used to generate energy, they must be
converted to a compound called
converted to a compound called glucose-6-phosphate.glucose-6-phosphate.
Conversion of a molecule of glucose requires 1 mole of ATP.Conversion of a molecule of glucose requires 1 mole of ATP.
1 mole of1 mole of glucoseglucose producesproduces 2 ATPs2 ATPs or 1 mole ofor 1 mole of glycogenglycogen producesproduces3 ATPs3 ATPs..
Provides energy forProvides energy for high-intensityhigh-intensityexercise (80-90% max) up toexercise (80-90% max) up to 2 minutes2 minutes..
IfIf OO22 is not availableis not available to accept the hydrogen ions in to accept the hydrogen ions in the mitochondria,the mitochondria, pyruvic acidpyruvic acid
can accept the hydrogen ions to form the
can accept the hydrogen ions to form the lactic acidlactic acid..
This accumulation of lactic acid This accumulation of lactic acid is a major limitation of is a major limitation of anaerobic glycolysis.anaerobic glycolysis.
This acidification of muscle fibers inhibits further This acidification of muscle fibers inhibits further glycogen breakdown because itglycogen breakdown because it
impairs glycolytic enzymes functions. impairs glycolytic enzymes functions.
In addition, the acid decreases the fibers’ calcium-binding capacity & thus mayIn addition, the acid decreases the fibers’ calcium-binding capacity & thus may
impede muscle contraction. impede muscle contraction.
Glucose
Glucose or or GlycogenGlycogen (Need 1 ATP) (Need 1 ATP) Glucose-6-phosphate Glucose-6-phosphate ATP ATP Pyruric acid Pyruric acid Lactic acid Lactic acid
Figure: Glycolytic system Figure: Glycolytic system
(Lactic acid is an acid with the chemical formula C
(Lactic acid is an acid with the chemical formula C33HH66OO88. Lactate is any salt of lactic. Lactate is any salt of lactic acid. When lactic acid releases H+, the remaining compound joins Na+
acid. When lactic acid releases H+, the remaining compound joins Na+ or K+ to or K+ to form aform a salt. Anaerobic glycolysis produces lactic acid, but it
salt. Anaerobic glycolysis produces lactic acid, but it quickly dissociates & the saltquickly dissociates & the salt (lactate) is form.)
(lactate) is form.)
3.
3. Oxidative systemOxidative system
The body’s most complex energy system, which The body’s most complex energy system, which generates energy by breakdown ofgenerates energy by breakdown of
fuels with the aid of O
fuels with the aid of O22(cellular respiration).(cellular respiration).
Because OBecause O22 is used, this is anis used, this is an aerobicaerobic process.process.
Has a very high-energy yield and yields more energy than the ATP-PC or glycolyticHas a very high-energy yield and yields more energy than the ATP-PC or glycolytic
system. system.
Oxidative production of ATP occurs within theOxidative production of ATP occurs within the mitochondriamitochondria..
Main energy production during endurance activities.Main energy production during endurance activities.
Oxidative production of ATP
Oxidative production of ATP involves:involves: i.
i. Oxidation Oxidation of of CHO CHO ii. ii. Oxidation Oxidation of of FatFat
i Oxidation of Carbohydrate i Oxidation of Carbohydrate
Involves 3 processes:Involves 3 processes:
a.
a. Aerobic glycolysisAerobic glycolysis b.
b. The Krebs cycleThe Krebs cycle c.
c. The electron transport chainThe electron transport chain
Aerobic glycolysis Aerobic glycolysis
In CHO metabolism, glucose or glIn CHO metabolism, glucose or glycogen is broken down to pyruvic acid ycogen is broken down to pyruvic acid viavia
glycolytic enzymes. glycolytic enzymes.
Hydrogen is released as glucose is metabolized to Hydrogen is released as glucose is metabolized to pyruvic acid.pyruvic acid.
In the presence of OIn the presence of O22, the pyruvic acid is , the pyruvic acid is converted intoconverted into acetyl coenzyme Aacetyl coenzyme A
(acetyl CoA). (acetyl CoA).
1 mole of glucose produces 2 moles of ATP or 1 mole of glycogen produces 3 moles1 mole of glucose produces 2 moles of ATP or 1 mole of glycogen produces 3 moles
of ATP. of ATP.
The Krebs cycle The Krebs cycle
The Electron Transport Chain The Electron Transport Chain
(Respiratory chain or cytochrome chain) (Respiratory chain or cytochrome chain)
The coenzymes carry the H atom (NADH & FADH) to the electron transport chain,The coenzymes carry the H atom (NADH & FADH) to the electron transport chain,
split into protons & electrons. split into protons & electrons.
At the end of the chain, HAt the end of the chain, H++combines with Ocombines with O22to form Hto form H220 (O0 (O22–accepting electrons),–accepting electrons),
thus preventing acidification. thus preventing acidification.
The electrons that were split from the H pass through a series of reactions (ETC)The electrons that were split from the H pass through a series of reactions (ETC)
& ultimately provide energy for the phosphorylation of ADP, thus forming ATP. & ultimately provide energy for the phosphorylation of ADP, thus forming ATP.
This process relies on OThis process relies on O22, referred to as, referred to as oxidative phosphorylation oxidative phosphorylation ..
Energy yield from Carbohydrate Energy yield from Carbohydrate
-
- 1 1 mole mole of of glycogen glycogen generates generates up up to to 39 39 moles moles of of ATP.ATP. -
- If 1 If 1 mole of mole of glucose, the glucose, the net gain net gain is 38 is 38 ATP (1 ATP (1 mole of mole of ATP is ATP is used forused for conversion to glucose-6-phosphate before glycolysis).
conversion to glucose-6-phosphate before glycolysis).
ii Oxidation of Fat ii Oxidation of Fat
Muscle & liver glycogen Muscle & liver glycogen stores provide only 1,200 – 2,000 kcal of energy.stores provide only 1,200 – 2,000 kcal of energy.
Fat stored inside the muscle fFat stored inside the muscle fibers (fat cells) can supply about ibers (fat cells) can supply about 70,000 – 75,00070,000 – 75,000
kcal. kcal.
Triglycerides (major energy sources) stored in fat cells Triglycerides (major energy sources) stored in fat cells in the skeletal musclein the skeletal muscle
fibers. fibers.
Triglycerides break down to its basic units to be used for energy: 1 mol of glycerolTriglycerides break down to its basic units to be used for energy: 1 mol of glycerol
to 3 moles of free fatty acids/FFA (= process
to 3 moles of free fatty acids/FFA (= process lipolysis lipolysis with lipases enzymes).with lipases enzymes).
FFA can enter blood & be transported throughout the body, entering muscle fibersFFA can enter blood & be transported throughout the body, entering muscle fibers
by diffusion. by diffusion.
ß Oxidationß Oxidation
-- Upon entering the muscle fibers, FFA are Upon entering the muscle fibers, FFA are enzymatically activated with energyenzymatically activated with energy from ATP, preparing FFA for catabolism (breakdown) within the
from ATP, preparing FFA for catabolism (breakdown) within the mitochondria.mitochondria. -- This enzymatically catabolism of fat (FFA) by the mitochondria =This enzymatically catabolism of fat (FFA) by the mitochondria = beta oxidation beta oxidation
(ß oxidation). (ß oxidation).
-- The carbon chain of FFA The carbon chain of FFA is cleaved into separate 2-carbon units of acetic acid.is cleaved into separate 2-carbon units of acetic acid. eg. FFA with 16-carbon chain, ß
eg. FFA with 16-carbon chain, ß oxidation yields 8 moles of acetic acid. oxidation yields 8 moles of acetic acid. EachEach acetic acid converted to acetyl CoA.
The Krebs Cycle & the Electron The Krebs Cycle & the Electron Transport ChainTransport Chain
-- Fat metabolism follows the same path as CHO metabolism.Fat metabolism follows the same path as CHO metabolism. -- Acetyl CoA formed by ß oxidation enters the Krebs cycle,Acetyl CoA formed by ß oxidation enters the Krebs cycle,
-- Krebs cycle generates HKrebs cycle generates H++ that is transported to the that is transported to the electron transport chain,electron transport chain, along with H
along with H++ generated during ß oxidation, to undergo oxidativegenerated during ß oxidation, to undergo oxidative phosphorylation – produce ATP, H
phosphorylation – produce ATP, H22O & COO & CO22..
-- The complete combustion of FFA molecule requires more OThe complete combustion of FFA molecule requires more O22 because FFAbecause FFA contains more carbon (C) than a glucose molecule.
contains more carbon (C) than a glucose molecule.
More carbon in FFA, more acetyl CoA is formed from the metabolism of fat, soMore carbon in FFA, more acetyl CoA is formed from the metabolism of fat, so
more enters the Krebs cycle & more electrons are sent to the e. t. chain.
more enters the Krebs cycle & more electrons are sent to the e. t. chain. (Fat(Fat metabolism generate more energy than glucose metabolism)
metabolism generate more energy than glucose metabolism)
Eg. Palmitic acid, 16-carbon FFA. The Eg. Palmitic acid, 16-carbon FFA. The combine reaction of oxidation, Krebs cycle, &combine reaction of oxidation, Krebs cycle, &
e. t. chain produce 129 molecules of ATP from 1 mole of palmitic acid.
e. t. chain produce 129 molecules of ATP from 1 mole of palmitic acid. (1 mol of(1 mol of glucose/glycogen = 38/39 moles of ATP)
glucose/glycogen = 38/39 moles of ATP)
40% of the energy released by metabolism is captured to form ATP, 60% is given40% of the energy released by metabolism is captured to form ATP, 60% is given
off as heat. off as heat.
4. Protein Metabolism 4. Protein Metabolism
Proteins (amino acids) are also used as body Proteins (amino acids) are also used as body fuels.fuels.
Some amino acids can be converted into glucose Some amino acids can be converted into glucose (gluconeogenesis)(gluconeogenesis)
Some can be converted into variousSome can be converted into various intermediates intermediates of oxidative metabolism (such asof oxidative metabolism (such as
pyruvate or acetyl CoA) to
pyruvate or acetyl CoA) to enter the oxidative process.enter the oxidative process.
Protein’s energy yield is not Protein’s energy yield is not easy because it contains nitrogen (N).easy because it contains nitrogen (N).
When amino acids are catabolized, some of the When amino acids are catabolized, some of the released N is used to form released N is used to form newnew
amino acids, but remaining N cannot be
amino acids, but remaining N cannot be oxidized by body.oxidized by body.
N is converted into urea & N is converted into urea & then excreted in the urine. This conversion use ATP, then excreted in the urine. This conversion use ATP, soso
some energy is spent in this
some energy is spent in this process.process.
In laboratory, 1 gram of protein = 5.65 kcal of energy.In laboratory, 1 gram of protein = 5.65 kcal of energy.
When metabolized in the body, energy used to convert N to urea, energy yield isWhen metabolized in the body, energy used to convert N to urea, energy yield is
only about 5.20 kcal per gram (8% less than the lab. Value). only about 5.20 kcal per gram (8% less than the lab. Value).
Healthy body utilizes little protein during rest & exercise (< 5-10% of total energyHealthy body utilizes little protein during rest & exercise (< 5-10% of total energy
expended). expended).
Enzyme Activity Enzyme Activity
Many enzymes are required for oxidation.Many enzymes are required for oxidation.
The enzyme activity of the The enzyme activity of the muscle fibers provides an indication of the oxidativemuscle fibers provides an indication of the oxidative
potential. potential.
The enzymes most frequently measured are SThe enzymes most frequently measured are SDH (succinate dehydrogenase), CSDH (succinate dehydrogenase), CS
(citrate synthase) & mitochondria enzymes in the Krebs cycle. (citrate synthase) & mitochondria enzymes in the Krebs cycle.
Endurance athletes’ muscles have oxidative enzyme activities 2-4 Endurance athletes’ muscles have oxidative enzyme activities 2-4 times greatertimes greater
than those untrained men & women. than those untrained men & women.
Fiber-type Composition Fiber-type Composition
Muscle’s fiber-type composition determines its oxidative capacity.Muscle’s fiber-type composition determines its oxidative capacity.
Slow-twitch (ST) fibers have a greater capacity for aerobic activity than the Fast-Slow-twitch (ST) fibers have a greater capacity for aerobic activity than the
Fast-twitch (FT) fibers because ST fibers have more mitochondria & higher twitch (FT) fibers because ST fibers have more mitochondria & higher concentrations of oxidative enzymes.
concentrations of oxidative enzymes.
More ST fibers, the More ST fibers, the greater oxidative capacity in the muscle.greater oxidative capacity in the muscle.
FT fibers are better suited for glycolytic energy production.FT fibers are better suited for glycolytic energy production.
Elite distance runners have reported to process more ST Elite distance runners have reported to process more ST fibers, more mitochondriafibers, more mitochondria
& higher muscle oxidative enzyme activity than
& higher muscle oxidative enzyme activity than untrained individuals.untrained individuals.
Endurance training enhances the oxidative capacity of fibers, especially FT fibers.Endurance training enhances the oxidative capacity of fibers, especially FT fibers.
Training that places demands on oxidative phosphorylation stimulates the muscleTraining that places demands on oxidative phosphorylation stimulates the muscle
fibers to develop more mitochondria that are
fibers to develop more mitochondria that are also larger & contain more oxidativealso larger & contain more oxidative enzymes.
enzymes.
By increasing the fiber’s enzymes for ß By increasing the fiber’s enzymes for ß oxidation, this training also enables theoxidation, this training also enables the
muscle to rely more heavily on fat for ATP production. muscle to rely more heavily on fat for ATP production.
With endurance training, even people with large % of With endurance training, even people with large % of FT fibers can increase theirFT fibers can increase their
muscles’ aerobic capacities. muscles’ aerobic capacities.
Endurance-traineEndurance-trained FT fiber d FT fiber will not develop the will not develop the same high-endurance capacity as asame high-endurance capacity as a
similarly trained ST fiber. similarly trained ST fiber.
Oxygen Needs Oxygen Needs
Oxidative metabolism depends on an adequate supply of OOxidative metabolism depends on an adequate supply of O22..
When at rest, body’s need for ATP is small, requiring minimal OWhen at rest, body’s need for ATP is small, requiring minimal O22 delivery.delivery.
As exercise intensity increases, to meet the energy demands, the rate of As exercise intensity increases, to meet the energy demands, the rate of oxidativeoxidative
ATP production also
ATP production also increases.increases.
In an effort to satisfy the muscle need for OIn an effort to satisfy the muscle need for O22, the rate & depth of the respiration, the rate & depth of the respiration
increase, improving gas exchange in the lungs, & heart
increase, improving gas exchange in the lungs, & heart beats faster, pumping morebeats faster, pumping more oxygenated blood to the muscle.
C. Causes of Fatigue C. Causes of Fatigue
1.
1. Depletion of PC oDepletion of PC or glycogenr glycogen..
The depletion of PC or glycogen will impa
The depletion of PC or glycogen will impairs ATP irs ATP production, thus fatigue is caproduction, thus fatigue is causedused by inadequate energy supply.
by inadequate energy supply.
2.
2. Accumulation of metabolic Accumulation of metabolic by-productsby-products..
Accumulation of hydrogen (H+) decreases muscle pH, causes muscle
Accumulation of hydrogen (H+) decreases muscle pH, causes muscle acidificationacidification (acidosis), which impairs the cellular processes that produce energy (inhibits the (acidosis), which impairs the cellular processes that produce energy (inhibits the action of glycolytic enzyme, slowing the rate of glycolysis & ATP production) & action of glycolytic enzyme, slowing the rate of glycolysis & ATP production) & muscle contraction.
muscle contraction.
3.
3. Failure of neural transmission in the Failure of neural transmission in the muscle fibermuscle fiber. Fatigue may occur at the. Fatigue may occur at the motor end plate, preventing nerves impulse transmission to the muscle fiber motor end plate, preventing nerves impulse transmission to the muscle fiber membrane, thus cause the neuromuscular block and leads
membrane, thus cause the neuromuscular block and leads to neuromuscular fatigue.to neuromuscular fatigue.
4. CNS may cause fatigue 4. CNS may cause fatigue..
Perceived fatigue usually leads to
Perceived fatigue usually leads to psychologically exhausted/fatigue and thepsychologically exhausted/fatigue and the exhausted feeling can often be psychologically trauma and
exhausted feeling can often be psychologically trauma and may inhibit the athlete’smay inhibit the athlete’s willingness to tolerate further pain or
SUMMARY
SUMMARY
1.
1. About 60% to 70% of the energy in human body is degraded to heat. TheAbout 60% to 70% of the energy in human body is degraded to heat. The remainder is used for mechanical work &
remainder is used for mechanical work & cellular activities.cellular activities. 2.
2. Humans derive energy from food sources – Humans derive energy from food sources – CHO, fats, & proteins.CHO, fats, & proteins. 3.
3. The energy humans derive from food is The energy humans derive from food is stored in a high-energy compound – stored in a high-energy compound – ATP.ATP. 4.
4. CHO provides about 4 kcal of energy per gram, compared to about 9 kcal of energyCHO provides about 4 kcal of energy per gram, compared to about 9 kcal of energy per gram for fat; but CHO is
per gram for fat; but CHO is more accessible. Protein can also provide enemore accessible. Protein can also provide energy.rgy. 5.
5. ATP is generated through 3 energy ATP is generated through 3 energy systems:systems:
The ATP-PC systemThe ATP-PC system
The glycolytic systemThe glycolytic system
The oxidative systemThe oxidative system
6.
6. In the ATP-PC system, PIn the ATP-PC system, Pii is separated from phosphocreatine through the action ofis separated from phosphocreatine through the action of creatine kinase. The P
creatine kinase. The Pii can then combine with ADP to form ATP. This system iscan then combine with ADP to form ATP. This system is anaerobic, and its main function is to maintain ATP
anaerobic, and its main function is to maintain ATP levels. The energy yield is levels. The energy yield is 1 mole1 mole of ATP per 1 mole of PC.
of ATP per 1 mole of PC. 7.
7. The glycolytic system involves the process of The glycolytic system involves the process of glycolysis, through which glucose orglycolysis, through which glucose or glycogen is broken down to pyruvic acid
glycogen is broken down to pyruvic acid via glycolytic enzymes. When conductedvia glycolytic enzymes. When conducted without oxygen, the pyruvic acid is converted to
without oxygen, the pyruvic acid is converted to lactic acid. 1 mole of lactic acid. 1 mole of glucose yieldsglucose yields 2 moles of ATP, but 1 mole of
2 moles of ATP, but 1 mole of glycogen yields 3 moles of ATP.glycogen yields 3 moles of ATP. 8.
8. The ATP-PC and glycolytic systems are major contributors of energy during theThe ATP-PC and glycolytic systems are major contributors of energy during the early minutes of high-intensity exercise.
early minutes of high-intensity exercise. 9.
9. The oxidative system involves breakdown of fuels with aid The oxidative system involves breakdown of fuels with aid of oxygen. This systemof oxygen. This system yields more energy than the ATP-PC or glycolytic system.
yields more energy than the ATP-PC or glycolytic system. 10.
10. Oxidation of carbohydrate involves glycolysis, the Krebs cycle, and the Oxidation of carbohydrate involves glycolysis, the Krebs cycle, and the electronelectron transport chain. The end result is H
transport chain. The end result is H22O, COO, CO22, and 38 or39 ATP molecules per, and 38 or39 ATP molecules per carbohydrate molecule.
carbohydrate molecule. 11.
11. Fat oxidation begins with ß oxidation of free fatty acids, then follows the sameFat oxidation begins with ß oxidation of free fatty acids, then follows the same path as carbohydrate oxidation: the Krebs cycle and
path as carbohydrate oxidation: the Krebs cycle and the electron transport chain.the electron transport chain. The energy yield for fat oxidation and it varies with the free fatty acid being The energy yield for fat oxidation and it varies with the free fatty acid being oxidized.
12.
12. Protein oxidation is more Protein oxidation is more complex because protein (amino acids) contains nitrogen,complex because protein (amino acids) contains nitrogen, which cannot be oxidized. Protein contributes relatively little to
which cannot be oxidized. Protein contributes relatively little to energy production,energy production, so its metabolism is often
so its metabolism is often overlooked.overlooked. 13.
13. Your muscles’ oxidative capacity depends on their oxidative enzyme levels, theirYour muscles’ oxidative capacity depends on their oxidative enzyme levels, their fiber-type composition, and oxygen availability.
fiber-type composition, and oxygen availability. 14.
14. Fatigue may result from depletion of PC or glycogen. Either of these situationsFatigue may result from depletion of PC or glycogen. Either of these situations impairs ATP production.
impairs ATP production. 15.
15. Lactic acid has often been blamed for fatigue, but it is actually the H+ Lactic acid has often been blamed for fatigue, but it is actually the H+ generatedgenerated by lactic acid that leads to fatigue. The accumulation of H+ decreases muscle pH, by lactic acid that leads to fatigue. The accumulation of H+ decreases muscle pH, which impair the cellular processes that produce energy &
which impair the cellular processes that produce energy & muscle contraction.muscle contraction. 16.
16. Failure of neural transmission may be Failure of neural transmission may be a cause of some fatigue. a cause of some fatigue. Many mechanismsMany mechanisms can lead to such failure, & all need further research.
can lead to such failure, & all need further research. 17.
17. The CNS may also The CNS may also cause fatigue, perhaps as a protective mechanism. Perceivedcause fatigue, perhaps as a protective mechanism. Perceived fatigue usually leads to
fatigue usually leads to physiological fatigue, and athletes who feel psychologicallyphysiological fatigue, and athletes who feel psychologically exhausted can often inhibit their willingness to continue exercise or to
exhausted can often inhibit their willingness to continue exercise or to toleratetolerate further pain.
SPS 211 EXERCISE PHYSIOLOGY SPS 211 EXERCISE PHYSIOLOGY
EXERCISE EXERCISE
(Basic Energy System) (Basic Energy System)
Name
Name : : _____________________________________ _____________________________________ Group Group : : _______________________ _______________________
1.
1. What What is is bioenergetics?bioenergetics?
________________________________________________________________________________ ________________________________________________________________________________
________________________________________________________________________________ ________________________________________________________________________________
2.
2. Draw the Draw the chemical pathway chemical pathway of ATP of ATP breakdown during breakdown during muscular contracmuscular contraction.tion.
3.
3. Name the Name the three three (3) m(3) methods tethods that cells hat cells generate generate ATP.ATP.
i. _____________________________________________________________________________ i. _____________________________________________________________________________ ii. _____________________________________________________________________________ ii. _____________________________________________________________________________ iii. _____________________________________________________________________________ iii. _____________________________________________________________________________ 4.
4. What is What is the role the role of PC of PC in the in the process of process of anaerobic metabolism?anaerobic metabolism?
i. _____________________________________________________________________________ i. _____________________________________________________________________________ ii. _____________________________________________________________________________ ii. _____________________________________________________________________________ iii. _____________________________________________________________________________ iii. _____________________________________________________________________________ iv. _____________________________________________________________________________ iv. _____________________________________________________________________________ v. v. _____________________________________________________________________________ _____________________________________________________________________________ 5.
6.
6. Draw the Draw the chemical pathways chemical pathways of the of the glycolytic system glycolytic system in energy in energy production.production.
7.
7. Define oxidative Define oxidative system.system.
i. ____________________________________________________________________________ i. ____________________________________________________________________________ ii. ____________________________________________________________________________ ii. ____________________________________________________________________________ iii. ____________________________________________________________________________ iii. ____________________________________________________________________________ iv. ____________________________________________________________________________ iv. ____________________________________________________________________________ 8.
8. Name the Name the three (3) three (3) processes that processes that involve the oxidative involve the oxidative of carbohydrate of carbohydrate in production in production of ATP.of ATP.
i. ____________________________________________________________________________ i. ____________________________________________________________________________ ii. ____________________________________________________________________________ ii. ____________________________________________________________________________ iii. ____________________________________________________________________________ iii. ____________________________________________________________________________ 9.
9. Name the Name the three (3) three (3) processes that processes that involve the oxidative involve the oxidative of fat of fat in production in production of ATP.of ATP.
i. ____________________________________________________________________________ i. ____________________________________________________________________________ ii. ____________________________________________________________________________ ii. ____________________________________________________________________________ iii. ____________________________________________________________________________ iii. ____________________________________________________________________________ 10.
10. List two (2) roles of oxygen in the process of aerobic metabolism.List two (2) roles of oxygen in the process of aerobic metabolism.
i. ____________________________________________________________________________ i. ____________________________________________________________________________
ii. ____________________________________________________________________________ ii. ____________________________________________________________________________
13.
13. Define the term aerobic mDefine the term aerobic metabolism.etabolism.
________________________________________________________________________________ ________________________________________________________________________________
________________________________________________________________________________ ________________________________________________________________________________
14.
14. Define the term anaerobic Define the term anaerobic metabolism.metabolism.
________________________________________________________________________________ ________________________________________________________________________________
________________________________________________________________________________ ________________________________________________________________________________
15.
15. Briefly discuss the function of glycolysis in Briefly discuss the function of glycolysis in bioenergetics.bioenergetics.
i. _____________________________________________________________________________ i. _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ ii. _____________________________________________________________________________ ii. _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ iii. _____________________________________________________________________________ iii. _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ 16.
16. Briefly explain the operation of the KrebBriefly explain the operation of the Krebs cycle.s cycle.
i. ____________________________________________________________________________ i. ____________________________________________________________________________ ____________________________________________________________________________ ____________________________________________________________________________ ii. ____________________________________________________________________________ ii. ____________________________________________________________________________ iii. ____________________________________________________________________________ iii. ____________________________________________________________________________ ____________________________________________________________________________ ____________________________________________________________________________ 17.
17. What is the role of NAD and What is the role of NAD and FAD in the Krebs cycle?FAD in the Krebs cycle?
________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________
18.
18. What is electron transpoWhat is electron transport chain?rt chain?
________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________ 19.
19. Explain briefly the possible causes of fatigue duExplain briefly the possible causes of fatigue during exercise.ring exercise.
i. _____________________________________________________________________________ i. _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ ii. _____________________________________________________________________________ ii. _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ iii. _____________________________________________________________________________ iii. _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ iv. ________________________________________________________________ iv. ________________________________________________________________ ________________________________________________________________ ________________________________________________________________ ________________________________________________________________ ________________________________________________________________
METABOLIC ADAPTATIONS TO TRAINNING METABOLIC ADAPTATIONS TO TRAINNING A. Adaptations to Aerobic Training
A. Adaptations to Aerobic Training
Aerobic training or cardiorespiratory endurance training, will Aerobic training or cardiorespiratory endurance training, will leads to improvedleads to improved
central & peripheral blood flow &
central & peripheral blood flow & enhanced capacity of muscle fibers to generateenhanced capacity of muscle fibers to generate greater amounts of ATP.
greater amounts of ATP.
The most observable changes with aerobic training are an The most observable changes with aerobic training are an increased ability toincreased ability to
performed prolonged submaximal exercise & an increased in one’s
performed prolonged submaximal exercise & an increased in one’s maximal aerobicmaximal aerobic capacity
capacity (VO(VO22max) ormax) or aerobic poweraerobic power.. 1. Adaptations in Muscle
1. Adaptations in Muscle
Repeated use of muscle fibers stimulates changes in
Repeated use of muscle fibers stimulates changes in their structure & their structure & function.function. Endurance training & the changes it produces in
Endurance training & the changes it produces in
Muscle fiber type,Muscle fiber type,
Capillary supply,Capillary supply,
Myoglobin content,Myoglobin content,
Mitochondrial function, &Mitochondrial function, &
Oxidative enzymes.Oxidative enzymes.
Muscle fiber type Muscle fiber type
Endurance training stresses ST muscle fibers more than Endurance training stresses ST muscle fibers more than FT fibers.FT fibers.
Consequently,Consequently, ST muscle fibers enlargeST muscle fibers enlarge..
FT FT bb fibers may adopt FT fibers may adopt FT aacharacteristics with endurance training, but percentagescharacteristics with endurance training, but percentages
of ST & FT
of ST & FT fibers do not appear to change.fibers do not appear to change.
Capillary supply Capillary supply
Aerobic training increases both the number of capillaries supplying each muscleAerobic training increases both the number of capillaries supplying each muscle
fiber and the number
fiber and the number of capillaries for a given cross-section area of muscle.of capillaries for a given cross-section area of muscle.
Therefore, both changes improve/increaseTherefore, both changes improve/increases blood perfusion in the s blood perfusion in the muscles, thusmuscles, thus
enhancing the exchange of gases, wastes, & nutrients between the blood and
enhancing the exchange of gases, wastes, & nutrients between the blood and musclemuscle fibers.
fibers.
Myoglobin content Myoglobin content
Muscle myoglobin content increases by 75%-80% with endurance training.Muscle myoglobin content increases by 75%-80% with endurance training.
Myoglobin stores OMyoglobin stores O22..
Mitochondrial function Mitochondrial function
Endurance training increases both in number and size of the Endurance training increases both in number and size of the skeletal muscleskeletal muscle
mitochondria, proving the muscle with much more efficient
Study of 27 Study of 27 weeks of training had increased number of mitochondria by weeks of training had increased number of mitochondria by 15% and15% and
the average size also increased, by about 35%. the average size also increased, by about 35%.
Oxidative enzymes Oxidative enzymes
Aerobic training also increases the activities of many oxidative enzymes.Aerobic training also increases the activities of many oxidative enzymes.
E.g. succinic dehydrogenase (SDH) & citrate synthase.E.g. succinic dehydrogenase (SDH) & citrate synthase.
Increase in enzymatic activities shows the increases in number & size ofIncrease in enzymatic activities shows the increases in number & size of
mitochondria and capacity of ATP production. mitochondria and capacity of ATP production.
2.
2. Adaptations to source of energyAdaptations to source of energy
Aerobic training increases the storage of carbohydrate (glycogen) & fAerobic training increases the storage of carbohydrate (glycogen) & f atsats
(triglycerides). (triglycerides).
Endurance-traineEndurance-trained muscle stores more gld muscle stores more glycogen than untrained muscle.ycogen than untrained muscle.
Endurance-trained muscle also stores more fat (triglyceride) than untrained muscle.Endurance-trained muscle also stores more fat (triglyceride) than untrained muscle.
Enzymatic activities involved in ß-oxidation of fat increases with training, thereforeEnzymatic activities involved in ß-oxidation of fat increases with training, therefore
increase FFA release, hence increase the use of fat
increase FFA release, hence increase the use of fat as energy source, so sparingas energy source, so sparing muscle glycogen, postponing exhaustion.
muscle glycogen, postponing exhaustion.
With aerobic training, the body increases the efficiency in With aerobic training, the body increases the efficiency in using fat as an using fat as an energyenergy
source for exercise, allows muscle & liver glycogen to be used at a slower rate. source for exercise, allows muscle & liver glycogen to be used at a slower rate.
Improvements in muscles’ aerobic capacity result in a greater capacity to Improvements in muscles’ aerobic capacity result in a greater capacity to produceproduce
energy, with a shift toward greater reliance on fat for ATP production. energy, with a shift toward greater reliance on fat for ATP production.
Endurance-trained muscles’ improved capaEndurance-trained muscles’ improved capacity to use city to use fat is caused by fat is caused by the enhancethe enhance
ability to mobilize FFA & the improved capacity to oxidize fat. ability to mobilize FFA & the improved capacity to oxidize fat.
In activities lasting several hours, these adaptations prevent early glycogenIn activities lasting several hours, these adaptations prevent early glycogen
depletion & thus ensure a
depletion & thus ensure a continued supply of ATP. Thus, endurance performance iscontinued supply of ATP. Thus, endurance performance is enhanced.
enhanced.
B. Training the Aerobic System B. Training the Aerobic System
1.
2.
2. Intensity oIntensity of Trainingf Training
Intensity is a critical factor in Intensity is a critical factor in improving performance. Adaptationimproving performance. Adaptations are specific tos are specific to
the speed & duration of
the speed & duration of training bouts, so those who perform at training bouts, so those who perform at higher intensitieshigher intensities must train at higher
must train at higher intensities.intensities.
Aerobic interval training Aerobic interval training
Involves repeated bouts of high-intensity performance separated by brief restInvolves repeated bouts of high-intensity performance separated by brief rest
periods. Based on ‘work: rest’ ratio. periods. Based on ‘work: rest’ ratio.
This training, although This training, although traditionally considered only anaerobic, generates aerobictraditionally considered only anaerobic, generates aerobic
benefits because the rest period is so brief that full recovery cannot occur, thus benefits because the rest period is so brief that full recovery cannot occur, thus the aerobic system is stressed.
the aerobic system is stressed.
Continuous training Continuous training
Prolonged bout of exercise, therefore athletes find it Prolonged bout of exercise, therefore athletes find it boring.boring.
However, aerobic benefits of both training interval & However, aerobic benefits of both training interval & continuous are about thecontinuous are about the
same. same.
C. Adaptations to Anaerobic Training C. Adaptations to Anaerobic Training
Anaerobic training leads to increase muscular strength and a greater tolerance forAnaerobic training leads to increase muscular strength and a greater tolerance for
acid-base imbalances during highly intense exercise. acid-base imbalances during highly intense exercise.
1.
1. Adaptations in Adaptations in the ATP-PC Systemthe ATP-PC System
Activities that emphasize maximal muscle force production (sprinting & weightActivities that emphasize maximal muscle force production (sprinting & weight lifting) rely most on the ATP-PC system for energy.
lifting) rely most on the ATP-PC system for energy.
Maximal efforts lasting less than 6-s demands on Maximal efforts lasting less than 6-s demands on the breakdown & resynthesis ofthe breakdown & resynthesis of ATP-PC.
ATP-PC.
Costill et al. Costill et al. (1979): Maximal knee extensions for training.(1979): Maximal knee extensions for training.
-- One leg was trained using 6-s maximal work One leg was trained using 6-s maximal work bouts that are repeated 10 times.bouts that are repeated 10 times. (ATP-PC system)
(ATP-PC system)
-- The other leg was trained with The other leg was trained with repeated 30-s maximal bouts. (Glycolyticrepeated 30-s maximal bouts. (Glycolytic system)
system)
-- Both forms of Both forms of training produced the same muscular strength gains (about 14%)training produced the same muscular strength gains (about 14%) & the same resistance to fatigue.
& the same resistance to fatigue.
-- Activities of muscle enzymes Activities of muscle enzymes creatine phosphokinase (CPK) & myokinase (MK)creatine phosphokinase (CPK) & myokinase (MK) increased as a result of the
increased as a result of the 30-s training, but were unchanged in the 6-s30-s training, but were unchanged in the 6-s training.
2.
2. Adaptations in Adaptations in the Glycolytic Systemthe Glycolytic System
Anaerobic training (30-s bouts) increased the activities of several glycolyticAnaerobic training (30-s bouts) increased the activities of several glycolytic enzymes. (phosp
enzymes. (phosphorylase, phosphhorylase, phosphofructokinase ofructokinase & lactate dehydroge& lactate dehydrogenase)nase)
The activities of these enzymes increase 10% - 25% The activities of these enzymes increase 10% - 25% with repeated 30-s trainingwith repeated 30-s training bouts, but change little with the short bouts (6-s).
bouts, but change little with the short bouts (6-s).
These enzymes are essential to the anaerobic yield of These enzymes are essential to the anaerobic yield of ATP; such training mightATP; such training might enhance glycolytic capacity & allow the
enhance glycolytic capacity & allow the muscle to develop greater tension for amuscle to develop greater tension for a longer period of time.
longer period of time.
This conclusion is not supported by results This conclusion is not supported by results of the 60-s sprint performance test.of the 60-s sprint performance test. The power output &
The power output & the rate of fthe rate of fatigue (decrease in power production) wereatigue (decrease in power production) were affected to the same
affected to the same degree after sprint training with both 6-s & degree after sprint training with both 6-s & 30-s training30-s training bouts.
bouts.
Performance gains with these forms of Performance gains with these forms of training result from improvement intraining result from improvement in strength rather than yield of ATP.
strength rather than yield of ATP.
# Anaerobic training increases the ATP-PC & glycolytic
# Anaerobic training increases the ATP-PC & glycolytic enzymes but has no effect enzymes but has no effect on theon the oxidative enzymes. Conversely, aerobic training leads to
oxidative enzymes. Conversely, aerobic training leads to increases in oxidative enzymes,increases in oxidative enzymes, but has no effect on the ATP-PC or glycolytic enzymes.
but has no effect on the ATP-PC or glycolytic enzymes. # This fact reinforces a
# This fact reinforces a recurring theme – physiological alterations resulting from trainingrecurring theme – physiological alterations resulting from training are highly specific to the type of training pursued.
are highly specific to the type of training pursued.
3.
3. Other Adaptations to AnOther Adaptations to Anaerobic Trainingaerobic Training
In addition to strength gains, the changes are improvements in In addition to strength gains, the changes are improvements in
Efficiency of movement,Efficiency of movement, Aerobic energetics,Aerobic energetics, Buffering capacity.Buffering capacity.
Efficiency of Movement Efficiency of Movement
Training at high speeds improves skill & Training at high speeds improves skill & coordination for performing at highercoordination for performing at higher intensities.
intensities.
Training at fast speeds & with
This changes is small, this enhancement of the This changes is small, this enhancement of the muscles’ oxidative potential willmuscles’ oxidative potential will assist the anaerobic energy systems’ efforts to meet
assist the anaerobic energy systems’ efforts to meet muscle energy needs duringmuscle energy needs during highly anaerobic effort.
highly anaerobic effort.
Buffering Capacity Buffering Capacity
Anaerobic training improves the muscles’ capacity to tolerate the acid Anaerobic training improves the muscles’ capacity to tolerate the acid thatthat accumulates within them during anaerobic glycolysis.
accumulates within them during anaerobic glycolysis.
Lactic acid accumulation is a major Lactic acid accumulation is a major cause of fatigue during sprint-type exercisecause of fatigue during sprint-type exercise because the H+ that dissociates from it is to interfere with both metabolism & the because the H+ that dissociates from it is to interfere with both metabolism & the contractile process.
contractile process.
BufferBuffer (such as bicarbonate & muscle phosphates) combine with hydrogen to (such as bicarbonate & muscle phosphates) combine with hydrogen to reducereduce the fibers’ acidity; thus they can delay the onset of fatigue during exercise.
the fibers’ acidity; thus they can delay the onset of fatigue during exercise. 8 weeks of anaerobic training has been shown to 8 weeks of anaerobic training has been shown to increasedincreased muscle bufferingmuscle buffering
capacity
capacity by 12% - 25% (Sharp et al., 1986).by 12% - 25% (Sharp et al., 1986).
Aerobic training has no effect on Aerobic training has no effect on buffer potential.buffer potential.
With the increased buffering capacity, sprint-trained athletes can accumulateWith the increased buffering capacity, sprint-trained athletes can accumulate more lactate in their blood & muscle during & following an all-out sprint to more lactate in their blood & muscle during & following an all-out sprint to exhaustion than untrained individuals.
exhaustion than untrained individuals.
This is because the H+ that dissociates from the lactic acid, not the lactate thatThis is because the H+ that dissociates from the lactic acid, not the lactate that accumulates, leads to fatigue.
accumulates, leads to fatigue.
With enhanced buffering capacity, muscle can generate energy for longer With enhanced buffering capacity, muscle can generate energy for longer periodsperiods before a critically high
before a critically high concentration of H+ inhibits the contractile process.concentration of H+ inhibits the contractile process.
D. Monitor
D. Monitoring Training ing Training ChangesChanges
VOVO22max is considered to be the max is considered to be the best means for evaluating training adaptations. Butbest means for evaluating training adaptations. But
the test is too
the test is too impractical for widespread use, & it cannot measure muscleimpractical for widespread use, & it cannot measure muscle adaptations to training.
adaptations to training.
Multiple measurements of blood lactate levels during Multiple measurements of blood lactate levels during an exercise bout of increasingan exercise bout of increasing
intensity have been proposed as a good means for monitoring progress of
intensity have been proposed as a good means for monitoring progress of training,training, but these tests are also
but these tests are also impractical.impractical.
Various methods for monitoring training adaptations have been tried, but theVarious methods for monitoring training adaptations have been tried, but the
easiest seems to be comparing single blood lactate
easiest seems to be comparing single blood lactate values taken at various timesvalues taken at various times during a training period, after a
during a training period, after a fixed-pace activity is performed. Even with hisfixed-pace activity is performed. Even with his method, many questions remain unanswered about what actually happens within the method, many questions remain unanswered about what actually happens within the body in response to the
SUMMARY
SUMMARY
1.
1. Aerobic training stresses ST muscle fibers more than Aerobic training stresses ST muscle fibers more than FT fibers. Consequently, theFT fibers. Consequently, the ST muscle fibers tend to enlarge with training. Although the percentages of ST & ST muscle fibers tend to enlarge with training. Although the percentages of ST & FT fibers do not appear to change, aerobic training may cause FT
FT fibers do not appear to change, aerobic training may cause FT bbfibers to take onfibers to take on more FT
more FT aafiber characteristics.fiber characteristics. 2.
2. The number of The number of capillaries supplying each muscle fiber increases with training.capillaries supplying each muscle fiber increases with training. 3.
3. Aerobic training increases muscle myoglobin content by about 75% Aerobic training increases muscle myoglobin content by about 75% to 80%.to 80%. Myoglobin stores oxygen.
Myoglobin stores oxygen. 4.
4. Aerobic training increases both the number and the size Aerobic training increases both the number and the size of mitochondria.of mitochondria. 5.
5. Activities of many oxidative enzymes are increased with aerobic training.Activities of many oxidative enzymes are increased with aerobic training. 6.
6. All the changes that occur All the changes that occur in the muscles, combined with adaptations in the Oin the muscles, combined with adaptations in the O22 transport system, lead to enhanced functioning of the oxidative system
transport system, lead to enhanced functioning of the oxidative system & improve& improve endurance.
endurance. 7.
7. Endurance-traineEndurance-trained muscle stores more gld muscle stores more glycogen than untrained muscle.ycogen than untrained muscle. 8.
8. Endurance-trained muscle also stores more fat (triglyceride) than untrained muscle.Endurance-trained muscle also stores more fat (triglyceride) than untrained muscle. 9.
9. Enzymatic activities involved in ß-oxidation of fat increases with training, thereforeEnzymatic activities involved in ß-oxidation of fat increases with training, therefore increase FFA release, hence increase the use of fat
increase FFA release, hence increase the use of fat as energy source, so sparingas energy source, so sparing glycogen.
glycogen. 10.
10. The ideal training regimen should have a The ideal training regimen should have a caloric expenditure of about 5000-6000caloric expenditure of about 5000-6000 kcal per week (715 – 860 kcal per day). There seems to be little benefit in the kcal per week (715 – 860 kcal per day). There seems to be little benefit in the aerobic system beyond this level.
aerobic system beyond this level. 11.
11. Intensity is also a critical factor Intensity is also a critical factor in improving performance. Adaptations arein improving performance. Adaptations are specific to the speed & duration of
specific to the speed & duration of training bouts, so those who perform at training bouts, so those who perform at higherhigher intensities must train at higher intensities.