Physiology
The study of the function of tissues, organs, and systems. E.g. muscle, nerve, heart, lungs, cardiovascular system
Exercise Physiology
The study of exercise on the function of these tissues, organs, and systems
Acute Exercise
Single bout of exercise
Training
Repeated bouts of exercise
Responses to environmental factors
heat, humidity, and altitude
(3) Physiologists that recieved the Nobel Prize for work related to muscle or muscular exercise
A.V. Hill: heat production during muscle contraction and recovery
Otto Meyerhof: Relationship of O2 consumption and lactic acid in muscle
August Krogh: Function of the capillary circulation
Other prominent scientists
JS Haldane: respiratory gas analyzer
CG Douglas: Douglas Bags
Christian Bohr: Bohr shift in oxyhemoglobin-dissociation curve
Harvard Fatigue Laboratory
D.B. Dill: Directed the lab 1927-1947
Conducted research in numerous areas (exercise, clinical, and environmental physiology)
Made careful and precise measurements
Public Health Service (1980) listed physical fitness as...
Listed "physical fitness and exercise" as one of the 15 areas of concern related to the country's overall health
Civil War until the First World War
Physical education primarily concerned with fitness. Many physical education leaders were trained in medicine.
Dr. Dudley Sargent
Hired by Harvard in 1879. Set up physical training programs with individual exercise prescriptions.
Health and Fitness in the Military
WW1&WW2: large numbers of draftees failed the induction exams due to mental and physical defects.
Physical programs began to resemble pre-military training programs.
Present Day: Obesity is major cause for rejecting recruits. "Too fat to fight
In the 1950s...
Autopsies of young soldiers from the Korean War showed significant coronary artery disease had already developed.
Hans Kraus: showed the American children performed poorly on a muscular fitness test compared to Europeans.
AAHPERD Youth Fitness Test (1957)
In the 1980s...
AAHPERD published the Health Related Physical Fitness Test Manual: focused on fitness rather than performance, testing. Concerned with obesity, cardio-respiratory fitness, low back function.
Cooper Institute FitnessGram: similar to AAHPERD test, included
Efforts of US Presidents:
Eisenhower: established the "President's Council on Youth Fitness"
Kennedy: changed name to "President's Council on Physical Fitness" and wrote The Soft American in sports illustrated.
Nixon: Changed name to "President's Council on Physical Fitness and Sp
Epidemiological Studies
Degenerative diseases relate to poor health habits, High-fat diet, smoking, inactivity.
An increased use of exercise tests to diagnose heart disease.
Large corporations developed "executive" fitness programs
American Heart Association (1992)
Made physical inactivity a major risk factor for cardiovascular diseases
CDC-ACSM Recommendation (1995)
Every US adult should accumulate 30 min of moderate intensity physical activity on most, or all days of the week.
Surgeon General's Report (1996)
60% adults do not meet recommendations. 25% not active at all
Physical Activity Recommendations and Guidelines:
US Physical Activity Guidelines (2008): based on review of research since 1996 Surgeon General's report.
US Physical Activity Guidelines mid-course report: focused on strategies to increase physical activity among youth
Dietary Guidelines for Americans (2
Physical activity has been shown to:
Lower the risk of dying prematurely and from heart disease
Reduce the risk of diabetes and high blood pressure
Help maintain healthy bones, muscles, and joints
Promote psychological well being
Help achieve and maintain a healthy body weight
Physical education to physical science
Reduced need for school-based physical ed teachers
Increased need for professionals in preventive and clinical settings
Programs include: biomechanics, physiology of exercise, fitness assessment, exercise prescription and leadership
Undergrad and Grad Study
Growth in the number of exercise physiology labs: opportunities for grad and undergrad education
Graduates from these labs contributed to the field: started new programs, research productivity
Integrated approach to study: importance of molecular biology
Professional Societies:
American Physiological Society (APS)
American Alliance of Health, Physical Education, Recreation, and Dance (AAHPERD)
American College of Sports Medicine (ACSM)
Training in Research
Increased specialization in research: necessary to compete for grants, students must specialize in their careers.
Basic Research: examines mechanisms underlying a physiological issue
Applied Research: examines responses to exercise, environmental, or nutr
Metric System:
The standard system of measurement for scientists, used to express mass, length, and volume.
System International (SI) units:
for standardizing units of measurement
Work
Work (J)= force(N) x distance(m)
Power
Power (W) = Work (J)/ time (Sec)
Ergometry
measurement of work output
Ergometer
Device used to measure work
Bench step ergometer
Cycle ergometer
arm ergometer
treadmill
How to calculate Bench step
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How to calculate cycle ergometer
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Treadmill
Calculation of work performed while a subject runs or walks on a treadmill is not generally possible when the treadmill is horizontal.
Quantifiable work is being performed when walking or running up a slope.
Incline of the treadmill is expressed in percen
How to calculateTreadmill
...
Work and Power
Understanding work and power is necessary to compute human work output and the associated exercise efficiency.
Work is defined as the product of force times distance
Power is defined as work divided by time
Direct Calorimetry
Measurement of heat production as an indication of metabolic rate
Foodstuffs + O2 > ATP + heat
Commonly measured in calories
1 kilocalorie (kcal)= 1000 calories
1 kcal =4,186 J or 4.186 kJ
Indirect Calorimetry
Measurement of oxygen consumption as an estimte of resting metabolic rate
Foodstuffs + O2> heat +CO2+H2O
VO2 of 2.0 L/min= 10 kcal or 42 kj/min
Open Circuit Spirometry
Determines VO2 by measuring amount of O2 consumed
VO2 = volume of O2 inspired-volume of O2 expired
Respiratory Exchange Ratio (RER)
VCO2/VO2
measured at the mouth.
Respiratory Quotient (RQ): measured at the cellular level. The more fit you are, the more oxygen you consume.
Calorimetry
The science that quantifies the heat release from metabolism
If fat provides a greater store of energy, why does CHO provide more energy relative to VO2?
CHO yields 6% more energy per liter of O2 than fat.
Fat utilization requires MORE O2.
The assumption of equality between RQ and RER cannot be made during the following:
1. Metabolic Acidosis: infaltes VCO2 causing RER>1.0
2. Non-steady state exercise: lower than expected VO2 and a likelihood for an inflated VCO2 and RER
3. Hyperventilation: causes a higher VCO2 and inflates the RER.
Absolute VO2
L/min
Relative VO2
ml/kg/min (takes into account body weight)
METS
Metabolic Equivalent.
1Met= resting metabolic rate
Estimation of Energy Expenditure
Engergy cost of horizontal treadmill walking or running: O2 requirement increases as a linear function of speed (m/min)
Estimation of O2 requirement of treadmill walking
Horizontal VO2 ml/kg/min): 0.1 (ml/kg/min) x speed (m/min)+3.5 (ml/kg/min)
Vertical VO2: 1.8 (ml/kg/min)x speed (m/min) x %grade
Estimation of O2 requirement of treadmill running
Horizontal VO2 ml/kg/min): 0.2 (ml/kg/min) x speed (m/min)+3.5 (ml/kg/min)
Vertical VO2: 0.9 (ml/kg/min)x speed (m/min) x %grade
Cycling O2 requirement
Resting VO2: 3.5 ml/kg/min
VO2 for unloaded cycling: 3.5 ml/kg/min
VO2 of cycling against external load: 1.8 ml/kg/m x work rate x body mass-1
Estimation of Cycling O2
Work rate in kpm/min
M=body mass in kg
7=sum of resting VO2 and VO2 of unloaded cycling (3.5+3.5)
VO2=1.8x work rate x body mass +7
Efficiency:
the ratio b/w the mechanical energy production of movement to metabolic energy used.
Decreases with increasing work rate. Curvilinear relationship between work rate and energy expenditure
Net Efficiency
ratio of work output divided by energy expended above rest
Of cycle ergometry=15-27%
% Net Efficiency
% net efficiency= work output/ energy expended above rest x 100%
Entropy
Energy lost by heat is not usable. Entropy = Heat
Factors that influence Exercise Efficiency
Exercise Work Rate: Efficiency decreases as work rate increases
Speed of Movement: there is an optimum speed of movement and any deviation reduces efficiency
Muscle Fiber Type: higher efficiency in muscles with greater percentage of slow fibers. Slow twit
Running Economy
Not possible to calcuate net efficiency of horizontal running.
Running Economy: Oxygen cost of running at given speed, lower VO2 at same speed indicates better running economy
Individual Differences: about 10% better in elite compared to less trained runn
Homeostasis: Dynamic Constancy
Homeostasis: maintenance of a constant and normal internal environment
Steady State
Physiological variable is unchanging, but not necessarily normal.
Balance between demands placed on body and the body's response to those demands.
Examples: Body temp and arterial blood pressure
Intracellular control systems
Protein breakdown and synthesis, energy production, maintenance of stored nutrients
Organ Systems
Pulmonary and circulatory systems, replenish oxygen and remove carbon dioxide
Biological Control System
Series of interconnected components that maintain a physical or chemical parameter at a near constant value.
Components: Sensor or receptor (detects changes in variable)
Control Center (Assesses input and initiates response)
Effector (changes internal env
Negative Feedback
Response reverses the initial disturbance in homeostasis.
Examples: increase in extracellular CO2 triggers a receptor, sends info to respiratory control center, respiratory muscles are activated to increase breathing, CO2 concentration returns to normal
M
Positive feedback
Response increases the original stimulus
Example: initiation of childbirth stimulates receptors in cervix, sends message to brain, release of oxytocin from pituitary gland, oxytocin promotes increased uterine contractions.
Gain of a Control System
Degree to which a control system maintains homeostasis.
System with large gain is more capable of maintaining homeostasis than system with low gain. Pulmonary and cardiovascular systems have large gains.
Regulation of Body Temp
Thermal receptors send messages to brain.
Response by skin blood vessels and sweat glands regulates temp.
Regulation of blood glucose
Function of the endocrine system
Requires the hormone insulin
Elevated blood glucose signals the pancreas to release insulin.
insulin causes cellular uptake of glucose.
Failure of Biological Control System results in disease
Failure of any component of a control system results in a disturbance of homeostasis. Example: Type 1 Diabetes.
Exercise
Exercise disrupts homeostasis by changes in pH, O2, CO2, and temp.
Control systems are capable of maintaining steady state during submax exercise in a coll environment.
Intense exercise or prolonged exercise in a hot/humid environment may exceed the abili
Adaptation
Change in structure or function of cell or organ system
Results in improved ability to maintain homeostasis
Acclimation
adaptation to environmental stresses. Heat stress in a hot environment
Cell Signaling
Communication between cells using chemical messengers. Important for maintaining homeostasis.
Cell Signaling Mechanism
Intracrine Signaling: Chemical Messenger inside cell triggers response.
Juxtacrine Signaling: chemical messenger passed between two connected cells
Autocrine Signaling: Chemical messenger acts on that same cell
Paracrine Signaling: chemical messengers act
Stress Proteins
Cells synthesize "stress proteins" when homeostasis is disrupted. Heat shock proteins repair damaged proteins in cell.
Stresses include: High temp, low cellular energy levels, abnormal pH, alterations in cell calcium, protein damage by free radicals.
Exer
Stress protein
Helps the cell repair itself after stress. You get them by getting out of homeostasis like exercise.
Cellular Protein Synthesis Overview
Exercise induced protein synthesis improves ability of cells to maintain homeostasis.
Process: 1. exercise activates cell signaling pathways
2. Activates transcriptional activator molecule.
3. Transcriptional activator binds to gene promoter region.
4. DN
Metabolism
Sum of all chemical reactions that occur in the body.
Anabolic reactions: synthesis of molecules. Building up; needs ATP
Catabolic Reactions: breakdown of molecules (Produce ATP)
Not 100% efficient.
Bioenergetics
Converting foodstuffs (fats, proteins, carbohydrates) into energy. Chemical reactions to do mechanical reactions
Studies/ describes how energy is converted form one form to another in a living cell/body.
Energy
Energy= the capacity or ability to perform work. The body converts chemical to mechanical energy.
1st Law of Thermodynamics
Energy cannot be created or destroyed, but can be changed from one form to another.
2nd Law of Thermodynamics
Energy transfer will always proceed towards randomness or in the direction of increased entropy.
34% efficient. Some of the energy is lost in heat or entropy. Entropy is unusable.
Cell Membrane (Sarcolemma)
Semipermeable membrane that separates the cell from the extracellular environment
Nucleus
Contains genes that regulate protein synthesis
Molecular biology
Cytoplasm
Fluid portion of cell.
Contains organelles
Mitochondria
Where ATP is actually produced in the mitochondria
Respiratory Assembly!!!
If it has DNA, it is capable of splitting.
Molecular Biology and Exercise Science
Study of molecular structures and events underlying biological processes. Relationship between genes and cellular characteristics they control.
Genes Code for specific cellular proteins. Process of protein synthesis.
Exercise training results in modificat
Endergonic Reactions
Require energy to be added.
Endothermic.
Uphill, getting you started.
Exergonic Reactions
Release energy.
Exothermic
Downhill, releases heat.
Coupled Reactions
Liberation of energy in an exergonic reaction drives an endergonic reaction. Exergonic drives endergonic. Drive eachother.
Cellular Chemical Reactions
Energy requiring reaction.
ADP+ P+energy> ATP
Energy Yielding Reaction
ATP> ADP+P+Energy (Atpase breaks it down) (Oxygen doesn't have to be present)
ATP: stored chemical energy that links the energy yielding and energy requiring functions within all cells
Oxidation (LEO)
Removing an electron. OIL RIG
Oxygen> lose
Reduction> gain
Oxidation and reduction are always coupled reactions
Reduction (GER)
Addition of an electron.
Often involves the transfer of hydrogen atoms rather than free electrons. Hydrogen atoms contain one electron and one proton. A molecule that loses a hydrogen also loses an electron and there is oxidized.
Redox Reaction
pyruvate+NADH+H> Lactate+NAD+
NADH is reduced and NAD+ is oxidized.
Need oxygen to get H+ away. Pyruvate will accept the H+ and turn into lactic acid.
NAD
Nicotinamide Adenine dinucleotide
Oxidized form: NAD+
Reduced Form: NADH
NAD+ + 2H > NADH
FAD
Flavin adenine dinucleotide
Oxidized form: FAD
Reduced form: FADH2
Both play an important role in transfer of electrons and both shuttle pair of hydrogens. Carrier molecules during bioenergetic reactions. 1. Pyruvate 2. Mytochondria or electron transport
Things that effect enzymes (Allosteric)
pH and temp. Helps go faster and easier.
Temp: small rise in body temp increases enzyme activity. Exercise results in increased body temp.
pH: changes in pH reduces enzyme activity. Lactic acid produced during exercise. Slows down enzyme.
Enzymes
Catalysts that regulate the speed of reactions.
Lower the energy of activation
Regulators and couplers.
To get it started.
Interact with specific substrates
Lock and key model. Coupler: puts them together.
Allosteric
a rate limiting enzyme, occur early in the metabolic pathway and determine the speed of reaction.
Diagnostic Application
Elevated lactate dehydrogenase or creatine Kinase in the blood may indicate a myocardial infarction.
Damaged cells release enzymes into the blood. Enzyme levels in blood indicate disease or tissue damage.
Classification of Enzymes
Almost all enzyme names end in -ase
Kinases
Add a phosphate group
Dehydrogenases
Remove hydrogen atoms
Oxidases
Catalyze oxidation-reduction reactions involving oxygen
Isomerases
Rearrangement of the structure of molecules
Carbohydrates
Glycogenisis. Include monosaccharides, disaccharides, and polysaccharides. Glucose: blood sugar. Can be broken down anaerobically.
Glycogen
Storage form of glucose in liver and muscle. Synthesized by enzyme glycogen synthase.
Glycogenolysis: Breakdown of glycogen to glucose. Can't Store alot because its big.
Glycolysis: breakdown of glucose.
Fats
Fatty acids, Triglycerides, Phospholipids, Steroids.
Beta oxidation: metabolic pathway to breakdown fats.
Fatty Acids
Primary type of fat used by the muscle
Tirglycerides
Storage form of fat in muscle and adipose tissue. Breaks down into glycerol and fatty acids via Lipolysis. 1Glycerol and 3 Fatty acids. Glycerol goes to bloodstream and then the liver.
Phospholipids
Not used as an energy source
Steroids
Derived from cholesterol. Needed to synthesis sex hormones.
Protein
Composed of amino acids. Can be used as an energy source for starving. Proteins are building blocks. Some can be converted to glucose in the liver. Gluconeogenis: 4 ways to make glucose: Allinean (protein), Glucerol (from fat), Pyruvate, lactate: Non carb
High energy Phosphates
Adenosine Triphosphate (ATP): consists of adenine, ribose, and three linked phosphates.
Synthesis: have to have energy to get started.
Formation of ATP
Phosphocreatine (PC) breakdown (Anaerobic) First 5 seconds
Degradation of glucose and glycogen: glycolysis 2-3 min
Oxidative formation of ATP (Krebs Cycle Down) maintains you
Anaerobic Pathways
Do not involve O2.
PC breakdown and glycolysis
Aerobic Pathways
Require O2
Oxidative Phosphorylation
ATP-PC system
Immediate source of ATP
PC + ADP > (CREATINE KINASE) ATP+ C
Phosphocreatine just wants to give up its phosphate to ADP
We ingest pc from protein
Glycolysis
Glucose> 2 pyruvic acid or 2 lactic acid
Energy Investment phase (endergonic): requires 2 ATP
Energy Generation Phase (Exergonic): produces 4 ATP, 2 NADH, and 2 pyruvate or 2 lactate.
Gluc4: the transporters that bring glucose in the cell.
Inusilin Mediat
Does Creatine Supplementation Improve Exercise Performance?
Depletion of PC may limit short term high intensity exercise. Creatine supplementation does not appear to pose health risks.
Creatine Monohydrates Supplementation
Increased muscle PC stores.
Some studies show improved performance in short term high intesnsity exercise. Inconsistent results may be due to water retention and weight gain. Increased strength and fat free mass with resistance training.
Lactic Acid
Lactic Acid = Lactate
Lactate is the conjugate base of lactic acid.
Lactic acid is produced in glycolysis. Rapidly disassociates to lactate and H+. The ionization of lactic acid forms the conjugate base (lactate)
Glycolysis definition
the energy pathway responsible for the initial catabolism of glucose in a 10/11 step process that begins with glucose or glycogen and ends with the production of pyruvate or lactate
Embden-Myerhof Pathway
Glycogenolysis
the process by which stored glycogen is broken down (hydrolyzed) to provide glucose
NADH
NADH's are indirect ATP's with oxygen present
Hydrogen and Electron carrier molecules
Transport Hydrogens and associated electrons: to mitochondria for ATP generation (Aerobic) or to convert pyruvic acid to lactic acid (anaerobic)
NADH is shuttled into Mitochondria
NADH produced in glycolysis must be converted back to NAD. By converting pyruvic acid to lactic acid, by shuttling H+ into the mitochondria.
Aspecific transport system shuttles H+ across the mitochondrial membrane. Located in the mitochondrial membrane.
Pyruvic acid to lactic acid
The addition of 2 H to pyruvic acid forms NAD and lactic acid. Catalyzed by lactate dehydrogenase (LDH)
Krebs Cycle (Citric Acid Cycle)
1.Pyruvic acid (3C) is converted to acetyl-CoA (2C) and CO2 is given off. 2. Acetyl CoA combines with oxalocetate (4C) to form citrate (6C). 3.Citrate is metabolized to oxaloacetate and 2 CO2 are given off.
4. Produces 3 molecules of NADH and 1 FADH2
Also
Electron Transport Chain
Oxidative phosphorylation occurs in the mitochondria.
Electrons removed from NADH and FADH2 are passed along a series of carriers (cytochromes) to produce ATP
Each NADH produces 2.5 ATP
Each FADH produces 1.5 ATP
Called the chemiosmotic Hypothesis!
H+ fro
Chemiosmotic Hypothesis of ATP formation
The process of pumping protons from matrix to inner membrane.
Electron transport chain results in pumping H+ ions across inner mitochon. membrane. Results in H gradient across membrane.
Energy released to form ATP as H ions diffuse back across the membran
End products of Glycolysis?
H2O, ATP, CO2, Entropy (heat)
Not NAD and FAD because they are there 24/7
1 turn of Krebs Cycle=
1 direct ATP, 3 indirect ATP, 10 ATP, 2 turns= 20 ATPs
1 Glucose produces how many ATP
32 ATP, energy provided by NADH and FADH also used in transport ATP out of mitochon.
3H+ must pass through H channels to produce 1 ATP
Another H needed to move the ATP across the mitochondrial membrane
Fats in Aerobic Metabolism
Triglycerides > glycerol and fatty acids (Lypolysis)
Fatty acids > acetyl CoA (Beta oxidation)
Glycerol is not an important muscle fuel during exercise
Protein in Aerobic Metabolism
Broken down into amino acids
Converted to glucose, pyruvic acid, acetyl Coa, and Krebs cycle intermediates.
The liver can turn glycerol into glucose along with allinean lactate and pyruvate
Beta Oxidation
The process of converting fatty acids to acetyl coa.
Breakdown of triglycerides releases fatty acids.
Fatty acids must be converted to acetyl coa to be used as fuel. Activated fatty acid into mitochondrion.
Fatty acid "chopped" into 2 carbon fragments for
Transamination
Beta oxydation. Starts with an amino acid. 12-15 ATP and no rate limiting enzyme. Branched chain amino acids can be used for energy: they have to go through transamination pathway.
Free Radicals
produced by the passage of electrons along the electron Transport chain. Free radicals react with other molecules in the cell. Aerobic exercise promotes the production of free radicals in mitochondra, this isnt due to oxidative phosphorylation in the mito
Efficiency of Oxidative Phosphorylation
One mole of ATP has energy yield of 7.3 Kcal.
32 moles of ATP are formed from one mole of glucose.
Potential energy released from one mole of glucose is 686 kcal/mole.
((32 mol ATP/mol glucose x 7.3 kcal/mole atp) / 686 kcal/mol glucose ) x 100 = 34%
Over
Rate limiting Enzymes
an enzyme that regulates the rate of a metabolic pathway.
Modulators of rate-limiting enzymes: Levels of ATP and ADP+P. High levels of ATP INHIBIT ATP production. Low levels of ATP and high levels of ADP+P stimulate ATP production.
Calcium may stimulate a
Glycolysis rate limiting enzyme
Phosphofructokinase
ATP-PC system rate limiting enzyme
Creatine Kinase
Krebs Cycle Rate limiting enzyme
Isocitrate Dehydrogenase
Electron Transport Chain rate limiting enzyme
Cytochrome oxidase
Interaction between Aerobic and Anaerobic ATP Production
Energy to perform exercise comes from an interaction between aerobic and anaerobic pathways.
Depends on duration and intensity of exercise.
Short term, high intensity activities: greater contribution of anaerobic energy systems (ATP-PC and Glycolisis)
Lon
Fitness and Exercise will increase enzymes and you'll go through the metabolic pathways faster.
We want to go into fat metabolism as fast as possible to spare glucose in case we starve.
Short Term, high intensity
Glycogen used first then glucose. To burn fat you need a lot of oxygen.
Uptake, why getting fit is more efficient
Increase in ATP, increase mitochondria # and Size, increase creatine phosphate stores, increase enzyme activity, increase # of capillaries (Exchange vessels), O2 deficit is smaller, less lactate acid is made, the fitter person will get into fat metabolism
Rest to Exercise Transitions
ATP production increases immediately.
Oxygen uptake increases rapidly.
Reaches steady state within 1-4 min.
After steady state is reached, ATP requirement is met through aerobic ATP production.
Initial ATP production through anaerobic pathways?
ATP-PC system
Oxygen Deficit
Lag in oxygen uptake at the beginning of exercise. Fit persons O2 deficit will be smaller than a nonfit person
Trained vs Untrained Subjects
Trained subjects have a lower oxygen deficit. Better developed aerobic bioenergetic capacity. Due to cardiovascular or muscular adaptations.
Results in less production of lactate and H. Fit people get into fat metabolism faster and steady state faster.
Recovery from Exercise
Oxygen uptake remains elevated above rest into recovery.
Oxygen Debt (EPOC): term used by AV Hill. Repayment of O2 deficit at onset of exercise.
Excess Post Exercise Oxygen Consumption: only 20% elevated O2 consumption used to repay O2 deficit.
Rapid Portion of O2 Debt
Resynthesis of stored PC
Replenishing muscle and blood O2 stores.
Sow Portion of O2 Debt
Elevated heart rate and breathing = increased energy need
Elevated body temp = increased metabolic rate
Elevated epinephrine and norepinephrine = increased metabolic rate
Conversion of lactic acid to glucose (gluconeogenisis)
Liver, heart, skeletal muscle
EPOC is greater following higher intensity exercise
Higher body temp. Greater PC depletion: additional O2 required for resynthesis.
Greater blood concentrations of lactic acid: greater level of gluconeogenesis.
Higher levels of blood epinephrine and norepinephrine.
Classic Theory of removal of Lactic Acid after exercise
Majority of lactic acid converted to glucose in liver.
How Lactic acid is removed after exercise
70% is oxidized: used as a substrate by heart and skeletal muscle.
20% converted to glucose
10% converted to amino acids.
Lactic acid is removed more rapidly with light exercise in recovery. Optimal intensity is 30-40% VO2 Max.
Metabolic Response to short term intense Exercise
First 1-5 sec: ATP through ATP-PC system
Intense exercise longer than 5 sec: shift to ATP production via glycolysis.
Exercise longer than 45 sec: ATP production through ATP-PC, glycolysis, and aerobic systems.
70% anaerobic/ 30% aerobic at 60 sec
50%/50%
Metabolic Response to Prolonged Exercise
Prolonged Exercise (>10 min): ATP production primarily from aerobic metabolism. Steady-state oxygen uptake can generally be maintained during sub max exercise.
Prolonged in hot or high intensity: Upward drift in oxygen uptake over time. Due to body temp.
Metabolic Response to Incremental Exercise
Oxygen uptake increases linearly until max oxygen uptake (VO2 max) is reached. No further increase in VO2 with increasing work rate.
VO2 Max: "physiological ceiling" for delivery of O2 to muscle. Affected by genetics and training.
Physiolocial factors inc
True Max
Max Heart Rate (220-age) w/i 10 beats. (Plateaus)
VO2 Max (Plateau)
RER (VCO2/VO2)measured at lung level at 1.1-1.15
Blood Lactate level: 8mmoles of lactic acid
What Energy do you use at max?
Purely carbs. Anaerobic (Glucose)
Venous Lactate
Lactate in the blood. More lactate in muscles because thats where it's formed.
Lactate Threshold
The first increase/inflection point.
The point at which blood lactic acid rises systematically during incremental exercise. Appears at 50-60% VO2 max in untrained subjects. At higher work rates (65-80% VO2 max) in trained subjects.
Also called: (Anaerobic
Explanations for the Lactate Threshold
Low muscle oxygen (hypoxia)
Accelerated glycolysis: NADH produced faster than it is shuttled into mitoch. and excess NADH in cytoplasm converts pyruvic acid to lactic acid.
Recruitment of fast twitch muscle fibers: LDH isozyme in fast fibers promotes lact
Mechanisms of the Lactate Threshold
Low muscle oxygen, Accelerated glycolysis, recruitment of fast-twitch fibers, Reduced rate of lactate removal.
Does Lactate cause Muscle Soreness?
NO! Caused by DOMS: Delayed onset muscle soreness. 24-48 hours after exercise.
Lactate removal is rapid (60 min) following exercise. Power athletes should experience DOMS after every work out. Microscopic injury to muscle fibers leads to inflammation. Eat
Respiratory Exchange Ratio (RER or R)
R= VCO2/VO2
R for fat (palmitic acid)
C16H32O2 + 23O2 > 16 CO2+ 16 H2O
VCO2/VO2= 16CO2/23O2=0.7
R for Carbohydrates (Glucose)
C6H12O6 + 6O2 > 6CO2 + 6H2O
VCO2/VO2 = 6CO2/6O2= 1.00
Low intensity exercise (<30% VO2 max)
fats are primarily fuel
50% vo2 max is ideal to burn a lot of fat
High intensity exercise (>70% vo2 max)
carbohydrates primarily fuel.
Cross Over Concept
Describes the shift from fat to CHO metabolism as exercise intensity increases.
Due to: Recruitment of fast muscle fibers
Inceasing blood levels of epinephrine.
Walking: 20%
Jogging: 30%
Running: 60-80%
Sprinting: 90%
At low exercise intensities (20% vo2 max)
High percentage of energy expenditure (66%) derived from fat.
Total Energy Expended is low (3 kcal/min)
Total Fat Oxidation is low (2 kcal)
High exercise intensities (60% vo2 max)
Lower % of energy (33%) from fat
Total energy expended is higher (9kcal)
Total Fat oxidation is higher (3 kcal)
Fat max
Highest rate of fat oxidation
Reached just before lactate threshold
Is low intensity exercise best for burning fat?
No, more like 50-60% of VO2 max
Prolonged Low intensity Exercise
shift from carbs metabolism toward fat metabolism due to increased rate of lipolysis.
Breakdown of triglycerides > glycerol + FFA (By enzymes called lipases)
Stimulated by rising blood levels of epineph.
Only time protein is used is starvation or long exe
Fats burn in the flame of carbohydrates
to burn clean fats you must have carbs also.
Glycogen is depleted during prolonged high intensity exercise
Reduced rate of glycolysis and production of pyruvate. Reduced Krebs cycle intermediates. Reduced fat oxidation (fats are metabolized by krebs cycle)
Muscle Glycogen
Primary source of carb during high intensity exercise and supplies much of the carbs in the first hour
Blood Glucose
From liver glycogenolysis. Primary source of carbs during low intensity exercise. Important during long duration exercise (as muscle glycogen levels decline)
Intramuscular Triglycerides
Primary Source of fat during higher intensity exercise
Plasma FFA
From adipose tissue lipolysis: Triglycerides > glycerol + FFA (Beta Oxidation)
FFA converted to acetyl- CoA and enters Krebs Cycle
Primary Source of fat during low intensity exercise
Becomes more important as muscle triglyceride levels declines in long du
MAX VO2
Oxygen Delivery and UPtake
Proteins broken down into amino acids
Muscle can directly metabolize branch chain amino acids and alanine. Liver can convert alanine to glucose
Only a small contribution (2%) to total energy production during exercise
May increase to 5-10% late in prolonged exercise. Enzymes that degrade proteins (proteases) are activated in long term exercise.
Lactate as Fuel Source
Can be used as a fuel source by skeletal muscle and the heart. Converted to acetyl CoA and enters Krebs Cycle.
Can be converted to glucose in the liver. Cori Cycle.
Lactate Shuttle: Lactate produced in one tissue and transported to another.
The Cori Cycle: Lactate as a Fuel Source
Lactate produced by skeletal muscle is transported to the liver. Liver converts lactate to glucose (Gluconeogenesis) Glucose is transported back to muscle and used as a fuel.
Neuroendocrine System
Endocrine System releases hormones. Nervous system uses neurotransmitters
Endocrine Glands
Release Hormones directly into the blood
Hormones
Alter the activity of tissues that possess receptors to which the hormone can bind.
Several classes based on chemical makeup: Amino Acid Derivatives, Peptides/protein, Steroids
Blood Hormone Concentration
The effect of a hormone on a tissue is determined by the plasma concentration.
Determined by:
1.Rate of secretion of hormone from endocrine gland (magnitude of input, stimulatory vs inhibitory input)
2. Rate of metabolism or excretion of hormone (at the r
Hormone Receptor Interactions
Hormones only affect tissue with specific receptors
Magnitude of effect dependent on: Concentration of the hormone, number of receptors on the cell, affinity of the receptor for the hormone.
Downregulation
Decrease in receptor number in response to high concentration of hormone
Less hormone can bind to the cell and higher concentrations of the hormone remain in the blood plasma. (Beta Blockers)
Upregulation
Increase in receptor number in response to low concentration of hormone.
More hormone can bind to the cell and lower concentrations of hormone in the blood plasma. (Beta Blockers)
Steroid Hormones
Lipid Soluble, Diffuse through cell membranes; receptors located w/i cell or nucleus.
Chemical structure is derived from or is similar to cholesterol.
Secreted by adrenal cortex, ovaries, testes, placenta.
Carried by protein transporters but must break th
Nonsteroid Hormes
Water Soluble. Cannot diffuse through cell membranes; receptors located on cell membrane.
2 types: Amino Acid Derivatives and protein or peptide hormones.
Hormones travel in the blood to their specific target organs.
Receptors are specific to hormones suc
Activating second messengers via G protein
Cyclic AMP, Ca++, calmodulin, Inositol triphosphate, Diacylglycerol.
Altering activity of DNA to modify protein synthesis
Steroid Hormones
Altering membrane transport
Insulin via tyrosine kinase
Hormones are secreted from endocrine glands
Hypothalamus and pituitary glands
Thyroid and parathyroid glands
Adrenal glands
Pancreas
Testes and Ovaries
Hypothalamus
Controls secretions from pituitary gland.
Stimulates the release of hormones from anterior pituitary gland. Provides hormones for release from posterior pituitary gland.
Anterior Pituitary Gland
Adrenocorticotropic Hormone (ACTH)
Follicle-stimulating hormone (FSH)
Luteinizing Hormone (LH)
Melanocyte Stimulating Hormone (MSH)
Thyroid-stimulating hormone (TSH)
Growth hormone (GH)
Prolactin
Posterior Pituitary Gland
Oxytocin
Antidiuretic Hormone (ADH)
Adrenocorticotropic Hormone (ACTH):
stimulates cortisol release from adrenal gland
Luteinizing Hormone (LH):
Stimulates production of testosterone and estrogen
Thyroid stimulating hormone (TSH)
Controls thyroid hormone release from thyroid gland
Growth Hormone
Stimulates release of insulin like growth factors (IGFs)
(IGF-1 in muscle responsible for muscle growth)
Essential growth of all tissues: amino acid uptake and protein synthesis. Long bone Growth.
Spares Plasma Glucose: Opposed insulin action to reduce th
Growth Hormone and Performance
Slow Acting Steroid.
GH increases protein synthesis in muscle and long bone growth. Used to treat childhood dwarfism, also used by athletes and elderly.
More adverse effects that benefits, no evidence that GH promotes strength gains (minimal strength gain
Posterior Pituitary Gland hormones
Oxytocin
Antidiuretic Hormone (ADH): reduces water loss from the body to maintain plasma volume. (Favors reabsorption of water from kidney tubules to capillaries)
Antidiuretic Hormone (ADH):
reduces water loss from the body to maintain plasma volume. (Favors re-absorption of water from kidney tubules to capillaries)
Release stimulated by high plasma osmolarity (thick blood: hemoconsuntration) and low plasma volume (Blood pressure goes up) Due
Every hormone goes up during exercise except...
Insulin. B/c insulin tells glucose to get stored and during exercise we don't want to store glucose
How ADH Conserves Body Water?
1. Muscular activity promotes sweating.
2. Sweating causes loss of blood plasma, resulting in hemoconcentration and increased blood osmolarity.
3. Increased blood osmolarity stimulates the hypothalamus
4. The hypothalamus stimultes the posterior pituitary
Thyroid Gland
Tied to metabolism. Stimulated by TSH. Triiodothyronine (T3) and Thyroxine (T4): slow and huge amounts. Establishment of metabolic rate; permissive hormones: permit full effect of other hormones.
Calcitonin and Parathyroid Hormone
Calcitonin
Released when blood calcium levels are high. Regulation of plasma Ca++. Blocks release from bone, stimulates excretion by kidneys. Critical to Osteoporosis.
Parathyroid Hormone
Released when blood calcium levels are low. Primary hormone is plasma Ca++ regulation. Stimulates release from bone, stimulates reabsorption by kidneys. Critical to osteoporosis. Exercise helps to lay down more bone.
Parathyroid Gland
Parathyroid Hormone: Primary hormone in plasma Ca++ regulation.
Stimulates Ca++ release from bone and reabsorption of Ca++ by kidneys.
Converts vitamin D3 into a hormone that increase Ca++ absorption from GI tract.
Adrenal Medulla
Secrete Adrenaline. Fast and Non steroid (Amine)
Secretes the catecholamines (Epin and norepin)
Fast acting hormones, part of fight or flight response.
Bind to Adrenergic Receptors (Alpha and Beta)
Effects depend on hormone used and receptor type.
Depends
Receptor Alpha 2
Decreases. The receptors stimulates G protein to form the second messenger.
Adrenal Cortex
Secretes steroid hormones (Derived from cholesterol)
Mineralcorticords: aldosterone, maintenance of plasma Na+ and K+
Glucocorticoids: Cortisol, regulation of plasma glucose
Sex Steroids: Androgens and estrogens, support prepubescent growth
Aldosterone
Slow acting, Similiar to ADH, maintaining blood volume & plasma.
Control of Na reabsorption and K secretion. (Na/H2O balance)
Regulation of blood volume and blood pressure: Part of renin-angiotensin-aldosterone system, all 3 hormones increase during exerc
The Renin-Angiotensin-Aldosterone Mechanism
1. Muscular activity promotes sweating and increases blood pressure.
2.Sweating reduces plasma volume and blood flow to the kidneys
3. Reduced renal blood flow stimulates renin release from the kidneys. Renin leads to the formation of angiotensin 1 which
Cortisol: Maintenance of plasma glucose
Promotes protein breakdown for gluconeogenesis.
Stimulates FFA mobilization
Stimulates glucose synthesis
Blocks uptake of glucose into cells: promotes the use of free fatty acids as fuel
Cortisol: Stimulated by
Stress via ACTH: part of General Adaptation Syndrome (GAS)
Exercise
Hahns Solye:
Father of stress research general adaptation syndrome.
1.Alarm
2. Resistence
3. Exhaustion
Adipose Tissue is an Endocrine Organ
In addition to storing triglycerides, adipose tissue also secretes hormones.
Leptin: controls appetite. Inflluences appetite through the hypothalamus. Enhances insulin sensitivity and fatty acid oxidation.
Adiponectin: Controls insulin sensitivity and pla
Pancreas
Both exocrine and endocrine functions. Dumping hormones into the blood. Fast, non steroid.
Secretes: Insulin (from beta cells), Glucagon (from alpha cells), Somatostatin (From gamma cells), and digestive enzymes and bicarbonate into the small intestine.
Insuline
From beta cells.
Promotes the storage of glucose, amino acids, and fats
Lack of insulin is called diabetes mellitus
Stores fuel
Glucagon
From alpha cells.
Mobilizes the fuel
Promotes the mobilization of fatty acids and glucose
Somatostatin
From gamma cells
Controls rate of entry of nutrients into the circulation.
Testosterone
Slow responding
Released form testes
Anabolic Steroid: promotes tissue (muscle) building and performance enhancement
Androgenic Steroid: Promotes masculine characteristics
Estrogen and Progesterone
Released from ovaries
Establish and maintain reproductive function
Levels vary throughout the menstrual cycle.
In general, testosterone and estrogen go up. Long intensity, they go down.
Anabolic Steroids and Performance
Initial studies showed no benefit for developing muscle mass.
Also associated with negative side effects: revert to normal after discontinuation
Widespread use has let to testing of competitive athletes
Most users aren't athletes.
Skeletal Muscle
Produces myokines when it contracts: stimulate glucose uptake and fatty acid oxidation
promote blood vessel growth in muscle
Promote liver glucose production and triglyceride breakdown.
Myokines and Cytokines are good; they are released and will call in p
Interleukin 6 (IL-6)
Produced in musce. Both proinflammatory and anti-inflammatory: IL-6 produced during exercise promotes anti inflammatory effects.
Regular exercise promotes anti inflam. environment: reduction in chronic inflammation and reduced risk of heart disease, cance
Glycogenolysis is related to exercise intensity
High intensity exercise results in greater and more rapid glycogen depletion. Breakdown of glycogen controlled by epin and norep.
Plasma epin is a powerful stimulator of glycogenolysis: high intensity exercise results in greater increases in plasma ep.
Al
Breakdown of muscle glycogen is under dual control
Epin-cyclic amp: via beta adrenergic receptors
Ca++ Calmodulin: enhanced during exercise due to Ca++ release from sarcoplasmic reticulum
Evidence for role of Ca++ calmodulin in glycogenolysis
Propranol (Beta receptor blocker) has no effect on muscle glycogen utilization.
Plasma Glucose maintained through 4 processes
1. Mobilization of glucose from liver glycogen stores
2. Mobilization of FFA from adipose tissue: spares blood glucose
3. Gluconeogenesis from amino acids, lactic acid, and glycerol.
4. Blocking the entry of glucose into cells: forces use of FFA as a fuel
Blood Glucose Homeostasis Controlled by hormones
Permissive or slow acting: thyroxine, cortisol, and growht hormone.
Fast acting: Epin, norep, insulin, and glucagon.
Thyroid Hormones
Act in a permissive manner to allow other hormones to exert their full effect: T3 enhances effect of epin to mobilize FFA from adipose tissue
No real change in T3 and T4 during exercise: thyroid stimulating hormone increases, gets metabolism ready
Cortisol
Exercise is good for stress, releases cortisol.
Slow acting hormone
Effects: stimulate FFA mobilization from adipose tissue, enchance gluconeogensis in the liver, decrease the rate of glucose utilization by cells
Effect of exercise: decrease during low in