BPK 310 Midterm

Why type of contraction causes the greatest PCr depletion?

Concentric contractions causes the most depletion of PCr > Isometric > Eccentric

What are the advantages and disadvantages of using portable gas exchange monitors for field-based energy expenditure measurements?

Considered gold standard (indirect calorimetry) ∙Advantage: portable ∙Limitations: covers their mouth as is sort of cumbersome so people might breathe differently

T/F: Muscle strength is exclusively determined by the number of motor units recruited during a task.

F: Includes muscles involved, muscle architecture/pinnation, contraction type, posture (muscles lengths), velocity, load

Differentiate between reliability and validity. How do you assess each?

Reliability: the reproducibility of the test across repeated tests and raters (enhanced by standardization) →Test-retest: have same participants perform the test more than once under same conditions →Inter-rater: have different testers administer the test Validity: does the test measure what it is intended to measure? →Show that the physiological demands of the test are highly similar to those of the job

What is excitation contraction coupling?

The mechanism by which the action potential triggers Ca²⁺ release and subsequent contraction

Where are flow limitations defined in a flow volume loop?

The tidal exercise flow-volume loops (extFVL) are overlaid onto the MFVL; flow limitations are defined for wherever the extFVL meet or exceed the MFVL boundary

Why are scientists unsure about the ventilatory control during exercise?

They really don't understand how ventilation is controlled because if you know certain things out, you can still breathe (lots of redundancy of control)

What is Fick's principle for calculating oxygen consumption? How can you use this formulae for gas exchange measurements?

VO₂= HR∙SV∙a-vO₂diff VO₂= Vi∙FiO₂-Ve∙FeO₂ Vi: minute ventilation (L/min) FiO₂: fraction of inspired gas that is O₂ Ve: minute ventilation (L/min) FeO₂: fraction of expired has that is O₂

What is ventilation (vs. respiration)?

Ventilation: breathing, inspiration and expiration Respiration: cellular consumption of O₂

What is the name of the physical abilities test for Canadian Wildland firefighters? What does it include?

WFX-FIT ∙Carry medium pump on back ∙Hand carry medium pump ∙Hose pack lift & carry on back ∙Advance charged hose →All completed in a gym walking back and forth over a ramp →Completed as a timed circuit (must complete within 14min, 30s to be eligible for "national exchange"

How does the body control ventilation during exercise?

We don't really know. ∙How is the need for increased ventilation sensed? ∙What delivers the signals? ∙What are the controllers/effectors?

How do you calculate the work rate on an ergometer?

Work rate= kg m/min = resistance (kg) x cadence (rpm) x flywheel circumference (m) **Go through slide 68 lecture 1-2 practice question

How do you conduct a physical demands analysis for the means of designing a pre-employment physical abilities test?

PDA: a systematic procedure to quantify, and evaluate all of the physical and environmental demand components of all essential and non-essential tasks of a job 1. Narrative summary of the job: purpose, tools and equipment, narrative description of duties (including environment, schedule, range of tasks) 2. Systematically record the properties for the following categories of physical demands: mobility & postures, MMH, reaching, dexterity tasks, proprioception, environmental conditions

How do we test human muscle contractile properties?

Isokinetic dynamometry →can include all contraction types: concentric, eccentric, isometric, isokinetic, isotonic →voluntary and electrically stimulated contractions Ex. Biodex

What is the primary role of calcium in muscle contraction?

Lecture 2-1 slide 37

Why do eccentric contractions consume less energy than concentric contractions for the same force generated?

Lecture 2-1 slide 37

How can you non invasively resolve individual motor unit potentials?

Linear array of electrodes

What is the size principle of motor unit recruitment?

Motoneurons with lowest thresholds (most excitable) are recruited first; tend to be smallest ∙Size: axon diameter (faster motor units have larger diameter and faster conduction velocities and spike amplitude), total membrane area, capacitance →Small motoneurons are more excitable (Voltage = current x resistance) →Smaller cells have less membrane surface area and less conductance channels hence less leakeage- voltage changes more readily to a given current

Give an overview of the neural and humoral control of ventilatory dynamics during exercise.

Neural: ∙Motor cortex ∙Muscle afferents ∙Lung stretch Humoral ("blood-borne"): ∙Centreal & peripheral chemoreceptors Initial changes in ventilation are controlled by the nervous system, while adjustments are maintained by whether or not you have the right balance of gases

What are the 2 fates of NADH and pyruvate?

Oxidation and lactate →both happen all the time but their relative rates differ

Outline the importance of oxygen and carbon dioxide for muscle energy production and homeostasis during exercise.

O₂: ∙final e⁻ acceptor in ETC ∙controller of rate of oxidative phosphorylation ∙its reduction creates free energy to synthesize ATP CO₂: ∙Involved in carboxylase reactions ∙bicarbonate buffers pH ∙needs to be removed →Bicarbonate system will accept protons in the blood and create CO₂ and H₂O

What are the 3 ergonomic strategies for reducing work-related injuries?

ie. MMH, low back injuries 1. Job Redesign: equipment, lower heights, "safe" lifting loads (psychophysical, biomechanical, physiological approaches) 2. Pre-employment testing: match worker's physiological capabilities with the physical demands of the job 3. Training & Education: ineffective due to poor compliance

What is the dominant factor of cardiac output during exercise? What percentage of VO₂max does it contribute, and what are its determinants?

∙Heart rate is dominant factor →>50% VO₂max →Main determinant of Q, especially at higher exercise intensities ∙Determinants: →Intrinsic pacemaker cells →Autonomic nervous system input, parasympathetic ↓ HR/sympathetic ↑ HR →Beta blockers ↓ HR and contractility- important for exercise prescription in clinical populations Q = HR x SV

Why might a serious athlete's hematocrit decrease with training?

∙Hemoglobin in erythrocytes enhances the transport of gases, which have limited solubility in blood ∙Sometimes with training, the hematocrit goes down because their is such a dramatic increase in blood volume that the concentration of RBC's goes down →This is called dilution pseudoanemia

What factors lead to stretching of the myocardium during exercise? What is the effect of a stretched myocardium?

∙Higher diastolic volumes stretch the myocardium, which increases pressure in the ventricles (preload), and increases stroke volume and stroke work ∙Exercise increases preload through enhanced venous return (Veins have valves to permit unidirectional flow and muscle contraction squeezes veins and forces blood towards heart ∙↑ Total blood volume, ↑ intrathoracic pressure, ↑ pumping action of skeletal muscle, ↑ venous tone

How do catecholamines control the heart and vasculature? How do they affect exercise?

∙Hormonal control of the heart & vasculature: catecholamines enhance sympathetic stimulation ∙Epinephrine & norepinephrine: ↑ HR, ↑ contractility, ↑ vasoconstriciton (alpha-adrenergic receptors) ∙Epinephrine only: ↑ vasodilation (beta-adrenergic receptors) ∙With training: submax exercise= E & NE decrease, allow greater blood flow to peripheral organs; max exercise: E & NE increased to maintain BP ∙Types I fibres less sensitive to adrenergic stimulation vs. type II

How does free energy of ATP hydrolysis vary with temperature and pH?

∙H⁺ ions participate in the reactions such that pH is a factor (normal muscle pH is 7.5, in intense exercise is can ↓ to 6.5-6.6)...so the more acidic, the less free energy released ∙The acidity is due to ATP hydrolysis and NOT lactate ∙Less overall energy to power muscle contraction with increased acidity

What is a motor unit?

∙Alpha motoneuron (leaving the spinal cord) and all the fibres it innervates ∙Typically the muscle fibres innervated by a specific neuron are not beside each other, they are usually spread out (ie. adjacent fibres are usually from different motor units) ∙# of fibres per MU varies (fine motor control ~10-100 fibres, vests laterals ~1000 fibres per MU) ∙Neuron AP stimulated contraction in ALL its fibres; properties of muscle fibres within a motor unit are the same

How do you assess the physiological demands of the job for the means of pre-employment physical abilities test?

∙Identify the criterion tasks: those that are essential and that are the most physically demanding for a given category →For wild land firefighting, ex. chain sawing, pulaski trenching, carrying pump on back, hand carrying pump, advancing charged hose, etc. ∙Measure physical variables ∙Use physiological measurement and assessment tools to estimate the demands (EE, HR, muscular demands, etc.) ∙Setting can be lab during simulated work or in the field during work

What is more important to physical performance & health- the ability to generate power or work?

∙If you are not doing work at a fast enough rate, you cannot perform. Power is probably the most important.

What are the 3 energy systems that supply ATP for cellular work?

∙Immediate: stored ATP (will deplete), phosphocreatine (PCr, buffers ATP), adenylate kinase reaction ∙Glycolysis (happens with or without O₂ so not useful to call is aerobic or anaerobic glycolysis) ∙Oxidative phosphorylation (produces a lot of ATP but slowly)

What adaptations to glycolysis would you expect to occur with sprint training?

∙In 10s, you would expect there to be a higher ATP yield because higher levels of glycolytic enzymes are present ∙Neural adaptations and a higher conversion to type 2 fibres that allow you to demand MORE

Distinguish power and capacity. Describe their implications for sprint and endurance performance.

∙In sprinting, you would generate high power and low capacity ∙Endurance performance, you would generate lower power but have a much higher capacity. →Maximum aerobic power is the fastest you can use aerobic energy stores

Why does mechanical power out not equal metabolic power in?

∙Increased entropy→ heat loss, chemical conversions, etc.

How does training affect the oxygen carrying capacity of the blood? How does it affect capillarization?

∙Increases O₂ carrying capacity ∙Hemoglobin increases due to increased number of red blood cells ∙Aerobic endurance training promotes capillarization in skeletal muscle

A common means of doping in endurance sports is injecting erythropoietin (Epo), which induces the proliferation of erythrocytes. How does this method work to enhance performance?

∙Increases the number of the red blood cells you have so you will have more oxygen carrying capacity

How do we process EMG signals?

∙Integrated EMG (iEMG); integrated the rectified signal overtime ∙Gives global measure of the collective activities of motor units within the detection area ∙Can tell whether a muscle is being recruited ∙Surface EMG with bipolar electrodes cannot resolve single motor unit activities →Information is also contained in the frequency spectrum (can plot the power spectra, etc.) →More sophisticated approaches (ex. decomposition techniques) are needed and used for proper interpretation, depending on the question or application

What is the purpose of the myosin light chains?

∙Myosin head→ actin binding site, ATPase ∙Light chains are regulatory; can get phosphorylated which increases force generation by that myosin molecule →Essential light chains:C1 & LC3, Regulatory light chains: 2 x LC2, Enhance myosin-actin binding ∙Myosin light-chain phosphorylation occurs on LC2, increases force generation

What are some names for the first oxygen uptake threshold? What about the second? Why do we use these names?

∙Naming depends on what measurements you use ∙Blood Lactate: 1= lactate threshold, 2= maximal lactate steady state ∙Gas exchange, ventilation: 1- gas exchange threshold or [First] ventilatory threshold, 2= maximal lactate steady state, respiratory compensation point, second ventilatory threshold, critical power/velocity, talk test

What are the "big 3" ATPases in skeletal muscle and whole-body metabolism? Why are these ATPases important for energy expenditure?

∙Na⁺/K⁺ ATPase ∙M-ATPase ∙SERCA →Skeletal muscle is very important for health because it is a major consumer of energy (SERCA in skeletal muscle may explain ~15-20% of whole body total daily energy expenditure) →The more fat you have, the more likely you are to develop a chronic disease →You can quantify the effect of a single type of protein

How do you calculate the actual free-energy change of a reaction?

∙Need to know the mass-action ratio (depends on the reactant and product [ ]'s and the temperature) ∆G=∆G⁰' + RTln([products]/[reactants]) →is the theoretical amount of work the reaction can do assuming 100% efficiency MAR= ([C]^c[D]^d/[A]^a[B]^b) →when reaction components are NOT at equilibrium, this ratio is the mass-action ratio Actual free energy change: ∆G= ∆G⁰' + RTlnMAR

How do endergonic reactions occur?

∙Not spontaneous ∙Coupling to exergonic reactions allows them to proceed ∙∆G is path independent- depends only on starting reactants and final products, not the intermediates ∙∆G are additive ∙You can have endergonic reactions within an exergonic pathway

Discuss the merits of a grip-strength test as a means for screening applicants to a job.

∙Not the best- you should do job related tasks →ex. if you carry a pump, then you should test carrying the pump, not just grip strength in isolation

Describe the structure of myosin.

∙One molecule of myosin has 2 heavy chains and 4 light chains →Head of myosin can bind to actin ∙Hexametric- 6 subunits (2 heavy chains, 4 light chains) →Sub fragments: S1 "head" & S2 "tail"

What is the creatine kinase shuttle hypothesis?

∙PCr is the transported phosphagen between sites of ATP hydrolysis and synthesis

What is the creatine kinase shuttle hypothesis?

∙PCr is the transported phosphagen between sites of ATP hydrolysis and synthesis →Spatial-temporal control mechanism? →Additional role for PCr

Explain the power-duration relationship in terms of human performance and exercise tolerance.

∙Peak power= maximum demand ∙Energy stores= maximum energy supply →As duration increases, the amount of power you can sustain decreases ∙Think in terms of energy systems (ATP and CP- can generate lots of ATP quickly but not sustainable, Anaerobic glycolysis- max power is lower than ATP and CP but has a higher capacity, Oxidative- the power is less but the capacity is much larger again

Compare the fatigue properties of predominantly slow twitch vs. fast twitch muscles.

∙Per unit muscle, the fast twitch muscle will be able to produce more force than the slow twitch muscle, but the slow twitch muscle can maintain its force for much longer than the fast twitch

What is load carriage? What addition demands does it introduce to the worker?

∙Performing a task with any additional load (mass) placed on the body →"Load"= >10kg ∙Load carriage introduces numerous additional demands: →EE →Gait →Mobility →Efficiency →Fatigue →Comfort →Risk of musculoskeletal injury Endurance needed to sustain extended duration work ∙Clothing and protective equipment can introduce load carriage AND thermal stress demands: ↑ EE, friction btwn clothing layers = ~3% ↑ in energy demand per layer, ↓ joint mobility, ↓ heat exchange

What is substrate level phosphorylation? What is the benefit of substrate level control?

∙Substrate-level phosphorylation: produce ATP but NOT via oxidative phosphorylation (independent steps in glycolysis) ∙Substrate-level control: increased turnover of ATP & NADH, glycogenolysis, and uptake of glucose from blood all help to drive glycolysis in the direction of pyruvate/lactate formation

What is myocardial "stress?"

∙Synonymous with myocardial oxygen consumption and stroke work ∙Myocardial VO₂ ~ rate-pressure product = HR x SBP ∙Different "types" of cardiac work: →"flow work" - ex. running →"pressure work"- ex. lifting weights, shoveling snow (more stressful on the heart)

What are the determinants of motor unit activation?

∙Task demands (type of contraction, force, velocity) ∙Muscle (much research is on small hand muscles, whereas exercise typically involves large muscle groups) ∙Fatigue (need to think of a way to maintain muscle contraction even due to the loss of force from fatiguing →Recruitment generally follow Henneman's Size Principle (MU with the lowest thresholds (most excitable) are recruited first; tend to be smallest)

What are some of the ways in which we can classify muscle fiber type?

∙Techniques don't always agree (typically the ATPase classification will line up with the myosin heavy chain classification) →Motor unit and muscle fiber properties are linked ∙Histochemistry (staining of tissue)→ myosin ATPase at different pH (I, IC, IIC, IIAC, etc.) ∙Enzyme biochemistry/muscle sections, colorimetric reactions→ glycolytic and oxidative pathway enzyme activities (GAPDH, SDH) ∙Immunological detection/immunoblotting, immunohistochemistry→ myosin heavy chains isoforms (MHC1, MHCIIa, MHCIIx/d) ∙Morphology→ colour, determined by myoglobin content (red/white) ∙Physiological→ contractile properties, fatigue properties (where you get "slow twitch" and "fast twitch" nomenclature)

How is the carbon dioxide dissociation curve different from the oxygen dissociation curve?

∙The CO₂ carried in the blood depends mainly on the partial pressure of CO₂. The carbon dioxide dissociation curve has a positive, almost linear, slope within the physiological range. →Haldane effect causes this curve to more up because it increases CO₂ unloading at the lungs.

What can you say about glycogen depletion during prolonged sub maximal exercise for trained and untrained individuals? What about in maximal-intensity sprint exercise?

∙Trained Submax: total glycogen depletion takes much longer than untrained (Oxidative fibres recruited more) ∙High intensity: change in glycogen levels for type II>I for all intensities (type 1 fibres are recruited in high intensity exercise)....but both fiber types are recruited in high-intensity exercise

Describe the structure of a thin filament.

∙Tropomyosin: 65 kDa, polymerizes into two helices that wrap around the f-actin helix ∙Troponin: globular, ~80 kDa →C= Ca²⁺ binding, I= inhibiting, T= tropomyosin-binding

Discuss the functional consequences of motor unit and muscle fibre types in terms of their contractile and fatigue properties.

∙Typically muscles express fiber types and express motor units that are in accordance with their functions

How do you conduct a job analysis for the means of designing a pre-employment physical abilities test?

∙Use words to describe what people do on the job ∙Focus on frequently performed &/or essential duties ∙Methods: literature and online resources, observe, oral recording of work activities, interviews, questionnaires, government databases (ex. O*NET)

What is a real-life application of monitoring RER?

∙Used to infer nutrient metabolism, but cannot tell exact nutrients (ex. glucose vs. other CHO)...need tracer studies ∙Application: services of exercise physiologists (energy usage analysis- for race day nutrition planning)

How is the work (power) portion of the EE equation assessed?

∙Using ergometers! ∙Efficiency= mechanical power (ergometer)/metabolic power in VO₂

What is the most common chemical intermediate for yielding energy in the body?

Adenosine triphosphate→ terminal phosphate bond is hydrolyzed to provide energy

Compare the Bohr and Haldane effects to the oxygen dissociation curve.

Bohr Effect (i.e. the rightward shift of the Hb-O₂ curve due to lowered pH and increased temperature, enhances O₂ dissociation in working muscle) →Facilitates the unloading of O₂ from Hb in contracting muscle Haldane Effect (oxygenation of Hb drives the dissociation of CO₂) →Causes CO₂ to be unloaded at the lungs

What factors affect diffusion rate of oxygen across membranes?

Diffusion rate is proportional to: ∆P∙A∙S/d∙sqrt(MW) ∆P- difference in pressure across membrane A- area of membrane S- solubility of gas d- diffusion distance MW- molecular weight of gas (ex. CO₂ has a much higher solubility coefficient than O₂ so it will diffuse faster

Which posture for measuring elbow flexion strength would lead to higher torque: elbow at 180 degrees or at 90 degrees?

Elbow at 180°

Predict the change in phosphorylation potential of ATP within a contracting muscle cell as it progresses from a fresh to fatigued state.

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Discuss the following statement from a thermodynamics perspective: weight management is all about calories in and calories out.

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Explain the roles of thermodynamics and kinetics in power production in an exercising human.

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What are 2 ways in which VO₂ kinetics contribute to exercise (or performance) tolerance?

1. Anaerobic energy used while VO₂ kinetics catch up during step changes in intensity (O₂ deficit) 2. Slow component reduces efficiency, increases CHO catabolism, increases heat production

What is the methodology for establishing a pre-employment physical abilities test?

1. Assemble the team 2. Conduct job analysis 3. Identify physical demanding tasks that are essential to the job; establish a subset to be assessed in detail 4. Characterize those tasks through a physical demands analysis: observe, measure, quantify 6. Develop physiological screening tests and procedures 7. Standardize the testing protocol (so you could do it anywhere) 8. Evaluate the reliability and validity of the tests and procedures 9. Develop, approve, and validate test performance standards and cut scores 10. Implement the tests, evaluate, refine

What are the 3 phases of oxygen kinetics?

1. Cardiodynamic component: abrupt increase in VO₂ due to blood returning from increased venous return 2. Primary (fast) component 3. Steady state (slow component; only at higher intensities, i.e.. the "heavy" domain)

How would you assess the accumulated oxygen deficit to estimate anaerobic energy provision during exercise? What are the limitations of assessing accumulated oxygen deficit?

1. Establish the relationship between VO₂ and work rate (usually linear) 2. Extrapolate the expected VO₂ for a supra maximal bout →Assume same efficiency (economy) (O₂ consumption takes a bit to catch up when you start exercising at a higher intensity, so you are spending anaerobic energy to make up for that) 3. Measure VO₂, while participant performs exercise at the supra maximal work rate Limits: assumes constant efficiency

What is the core mission of occupational physiology?

Assess work demands and to ensure they are matched to worker physical capabilities ∙Consequences of demand-capability mismatch: →physical and mental strain of worker →reduced productivity and efficiency →compromised worker safety: enhanced risk of overexertion, fatigue, injury, and illness ∙The physical demand is determined by the task and by modifying variables: →Nature of the task: load, distance to lift/move →Modifying variables: environmental conditions (clothing and load carriage), concomitant mental/psychological stress, lack of sleep/nutrition/travel/circadian rhythm disruption

Differentiate between metabolic "control" vs. "regulation." What is the key regulated variable for cellular energy homeostasis?

Control: the effect of a signal on the flux through an enzyme or pathways, where changes in the signal result in a change in the rate of enzyme or pathway, ATPases, triggered by the motor neuron (ex. hormone, it is not actually involved in the change but signal the change in shape/etc. of an enzyme) Regulation: maintenance of some parameter in a relatively constant state, despite changes in external signal or in fluxes through the pathways in which the parameter is involved ∙Key regulated variable= free energy of ATP hydrolysis →[NADH]/[NAD⁺] ratio →[reactive oxygen species]

How do you use heart rate directly to determine energy expenditure? How can you do this indirectly?

Directly= Determine the Hr-VO₂ relationship: →perform graded exercise test on ergometer →record stead-state HR and VO₂ at each stage (work intensity) →fit regression equation →measure mean HR during work and predict average VO₂ →highest validity is for steady-state prediction and for work activities that sue the same muscle groups as the ergometer modality Indirectly= heart rate reserve (max HR-resting HR= HRR) is statistically equivalent to VO₂ reserve

Why is it best to think of strength as a construct?

Definition: the capacity to produce a force or torque with voluntary muscle contraction →Direct measure requires invasive procedures (tendon buckle...not ethical) →Its measurement depends on: muscles involved, muscle architecture/pinnation, contraction type, posture (muscle lengths), velocity, load

What are the primary classes of physiological demands in occupational physiology?

Demand for endurance (fatigue resistance) →aerobic power →EE →circulatory strain Demand from environmental factors →temperature →altitude →microgravity →pollution Muscular demands →muscular strength →muscular endurance →postures (ie. awkward postures for long periods of time or repetitive awkward postures)

What is the most convenient alternative to indirect calorimetry to assess energy expenditure?

Heart Rate! ∙Heart rate is mostly linearly related to VO₂ (VO₂ is mostly linearly related to work rate (EE)) ∙Heart rate data can be used in two ways: →Directly to estimate energy expenditure, if the HR-VO₂ relationship is known →Indirectly as an index of overall physical strain ∙Can also be used as an indirect measure of circulatory strain →More rigorous: use the rate-pressure product if ambulatory measurement of blood pressure is available rate-pressure product = heart rate x systolic blood pressure

What is Henry's law? How is it related to ventilation?

Henry's Law: concentration of dissolved gas is proportional to its partial pressure →Gases exert partial pressure in gas and liquid phases ∙Ventilation establishes pressure gradients of gases from sites of production to excretion- O₂ (gradient creates a driving force for transport)

What is occupational physiology? How is it relevant to Kin?

Ie. Work physiology: may be though of as the basic science of ergonomics. It deals with the musculoskeletal, cardiovascular, and adaptive mechanisms that allow the human body to adjust to different workloads and stresses and identifies the sources of inefficency, overuse, and physical stress on the body related to work. The field may subsume exercise physiology and overlaps sports physiology and kinesiology. It is a sister disciple to biomechanics. Related to Kin: →Job Analysis- procedures to identify the content of a job in terms of activities involved and attributes or job requirements needed to perform the activities →Physical (physiological) demands analysis- systematic evaluation of physical performance and mobility requirements for a job (restricted to physical dimension)

How does the free energy of a system determine the direction of the reaction?

In chemical transformations, the standard free energy is the free energy released as 1M of reactants and products proceed to equilibrium concentrations ∆G⁰'=-RTlnK(eq) Keq'=([C]^c*[D]^d)/([A]^a*[B]^b) ∙if Keq>1, ∆G<0, proceeds forward ∙if Keq=1, ∆G=0, equilibrium ∙if Keq<1, ∆G>0, proceeds in reverse

Would an isokinetic elbow flexion test at 120 degrees/second be a good test for assessing lifting capacity?

No, because as you move through your ROM you will recruit more muscles

How do you calculate power? Why do we not calculate the power of running?

Power (W)= VO₂max x %VO₂max x efficiency (W; mL∙O₂∙min⁻¹) →Power, ie. ergometry ∙Can't accurately measure the power on a treadmill so instead we measure velocity Velocity (km∙h⁻¹)= VO₂max x %VO₂max x economy (km/h; (mL∙O₂∙min⁻¹)⁻¹ →Can't say economy=efficiency because velocity isn't the same as power (different units) →Economy- conversation of metabolic energy into mechanical energy →%VO₂max- fraction of VO₂max that can be sustained for the duration of the task (reflects the first and second thresholds→ the relative importance of which is determined by the duration of exercise bout) →VO₂max- maximal oxygen consumption= max power from aerobic energy sources

What is the final destination of the reducing equivalents in metabolism?

The electron transport chain (= a series of reducing reactions; transfer of electrons to progressively more electronegative acceptors) →NADH enters at pump1 and FADH2 enters pump 2 ∙The free energies of these reactions are used to pump protons into the mitochondrial intermembrane space, forming an electrochemical gradient ∙The gradient creates a driving force for H⁺ diffusion back into mitochondrial matrix through the F₁-F₀ ATP synthase (this dissipates the potential energy difference on either side of the membrane) ∙The free energy released by diffusion powers the synthesis of ATP

What applications regarding athletic performance are used as a result of knowing thresholds?

Thresholds are among the most useful physiological variables to know regarding athletic performance ∙Demarcate training intensity zones →Normalize exercise intensity →Monitor training (Benchmark) ∙Are metrics of aerobic fitness; useful for longitudinal monitoring ∙Pacing strategies (including W' monitoring)

Can fiber type shifting occur?

Yes! ∙Well est. that IIa-IIx interconversions occur ∙More controversial as to whether I-II interconversions occur; velocity is likely key variable (but more and more evidence is emerging)

How does oxygen get from the air to the mitochondria for cellular respiration?

→Inspired O₂ moves into alveoli then dissolves in plasma and binds to erythrocytes, then the O₂ bound to Hb in erythrocytes dissolves and must pass through plasma then interstitial fluid THEN into cells for consumption →Breathing exchanges alveolar gas with ambient gas (increases Po2 & decreases Pco2 in alveoli); expired air has a higher PO₂ and lower PCO₂ than the air in the lungs due to anatomical dead space →Gases diffuse across several fluid layers & membranes between alveoli and erythrocytes (diffusion rate is determined by the surface area and diffusion distances)

What is enthalpy? Why is it important?

∆H= ∆G + T∆S ∙∆H→ enthalpy change= heat transferred (units= J/mol) ∙∆G→ Gibbs free energy (energy available to do work, ie. exercise (units= J/mol)) ∙T∆S→ energy unavailable to do work, "measure of disorder" of a system (units= J/mol K) (This is the relationship between thermodynamic quantities at a constant temperature and pressure) Endergonic rxn: ∆G>0 (consumes free energy) Exergonic rxn: ∆G<0 (releases free energy) Endothermic rxn: ∆H>0 (increase enthalpy of the system) Exothermic rxn: ∆H<0 (decrease enthalpy of the system)

What are the 5 inputs on the cardiovascular control centre the heart and circulation?

∙"Central command" (higher brain centres' subthalamic locomotor region controls heart are and left ventricular contractility by controlling efferent sympathetic (+) and parasympathetic (-) nervous system signals ∙Central and peripheral chemoreceptors sense ↑Pco₂, ↓Po₂, ↓pH and stimulate the CVC ∙The hypothalamus is particularly active in controlling circulation in response to thermal stresses (anterior: vasodilator skin vessels (heat); posterior: vasoconstrict (cold)) ∙Baroreceptors establish the blood pressure "set point"; respond to perturbations via negative feedback (inhibit CVC pressor centre) ∙Muscle afferents serve as part of feedforward control CVC upon the initiation of contraction & limit tissue vasodilation during intense exercise →2 types of muscle afferents: Type III- sense stretch & mechanical deformation; Type IV-sense chemical stimuli, ex. K⁺, pH, prostaglandins

Why are muscular demands assessed as part of physical demands analyses (PDA's)?

∙"Manual materials handling" (MMH) is a major feature of some jobs →Lift, carry, push, pull, lower loads (may constitute "physically demanding tasks") ∙Forceful exertions strain the worker (local fatigue, muscle damage and soreness, injury (especially low back), discomfort (pain/stiffness/tension)) ∙MMH can have effects that hinder productivity, efficiency, and safety

What is the energy yield from glycolysis?

∙# of ATP of coenzymes formed or consumed: 2 ATP + 2 NADH ∙# of ATP ultimately formed or consumed: 6-8 ATP (theoretically)

Explain the motor unit phenomena: decrecruitmet, motor unit substitution/rotation, afterhyperpolarizaiton, and late adaptation.

∙* Derecruitment *: during progressive force decrease in isometric contraction; motor units tend to stay recruited but fire at slower frequencies (still adheres to the size principle) →ie. motor units stay recruited below their original recruitment thresholds even as force declines- they derecruit in order of highest to lowest ∙Sub maximal prolonged isometric contractions: *Motor unit substitution & Rotation* →An active motor unit may be derecruited while another with similar threshold is recruited- substitution (if they switch again it is considered rotation) →May prevent fatigue ∙*Afterhyperpolarization*: overshoot in membrane potential after an AP, which lowers probability of subsequent depolarization; higher-threshold motor units recover AHP faster ∙*Late Adaptation*: during sustained contractions, the firing frequencies of the motor units ↓'s; more prevalent in higher-threshold motor units (Both AHP and late adaptation thought to be due in part to leakage via Ca²⁺-activated K⁺ channels)

What are the products of one turn of the tricarboxylic acid cycle? Where does the cycle occur?

∙3 NADH ∙1 FADH₂ ∙1 GTP ∙2 CO₂ →Occurs in the mitochondrial matrix

What factors determine the actual free energy change in ATP hydrolysis in a muscle cell?

∙ATP and ADP exist as MgATP² and MgADP ([ ]'s << 1M) SLIFE 29

What does it mean that "the powers and capacities tradeoff for the energy system?"

∙ATP/PCr is the highest power, lowest capacity ∙Oxidative phosphorylation is the lowest power, highest capacity →Peak power sets maximum demand →Energy stores set capacity →Tradeoff is reflected in the power-duration relationship

How does the relative contribution of each energy system during performance of different durations change?

∙ATP/PCr starts out as the main contributor for a short time and quickly depletes ∙Glycolysis kicks in right after ATP-PCr is finishing and slowly depletes ∙Aerobic starts very low and increases in contribution over time →The are all contributing to ATP the whole time →Ex. exhaustive exercise after 30s is 73% anaerobic and 27% aerobic

How are accelerometers, GPS, and doubly-labelled water used to assess work rate/energy expenditure?

∙Accelerometer: provides "count" data (not step count) →Device is calibrated against gold standard measurement (ie. indirect calorimetry) →Defining valid thresholds can be challenging though (because for a very fit person, 6 MET's is not very much) ∙GPS: uses velocities & slopes (from elevation data) as inputs to ACSM equations or other predictive equations, compendium of physical activities ∙Doubly-Labeled Water: suitable for measuring energy expenditure over a period of several days-weeks; typically used in occupational physiology research studies

What are the possible fates of pyruvate in oxidative phosphorylation? What does the pyruvate dehydrogenase reaction yield?

∙Accepts reducing equivalents via LDH reaction → lactate ∙Enables donation of reducing equivalents by CoA via PDH reaction → acetyl- CoA ∙Pyruvate dehydrogenase yields 1 acetyl-CoA & 1 NADH + H⁺ from pyruvate, CoA, & NAD⁺

Which energy systems are used for supplying ATP in the following scenarios? -100m sprint -Marathon -Prime sprint in cycling race -8hr mining shift -50m freestyle swimming

∙All of the energy systems are involved in supplying ATP for muscle contraction →but the relative contributions will be very different

What are the "sensors" to breathe?

∙Central chemoreceptors sense pH and Pco₂ of cerebrospinal fluid and provide afferent input to the inspiratory centre (which relays to the expiratory centre) ∙Peripheral chemoreceptors in aortic and carotid bodies sense reduced arterial Po₂ and increased Pco₂ and provide input to inspiratory centre ∙Group III and IV muscle afferents sense catabolic byproducts and provide input to inspiratory centre

Differentiate between anaerobic capacity and anaerobic work capacity. How are they related?

∙Anaerobic Capacity: maximal amount of ATP resynthesizes via anaerobic metabolism (by the whole organism) during a specific type of short-duration maximal exercise reflects chemical energy ∙Anaerobic Work Capacity: the mechanical equivalent of anaerobic capacity →Total amount of external (mechanical) work performed during a specific type of exhausting exercise which is of a sufficient duration to incur a near-maximal anaerobic ATP yield, given that this ATP yield exceeds that from oxidative metabolism. (reflects mechanical work) →Anaerobic capacity and anaerobic work capacity are related by the efficiency of the chemical-to-mechanical energy transduction

What does an assessment of the maximal accumulated oxygen deficit (MAOD) estimate?

∙Anaerobic capacity →Find duration for which AOD is maximal (~2-3 minutes)

Is ATP generated more efficiently via aerobic or anaerobic metabolism in exercising human skeletal muscle?

∙Anaerobic metabolism!

Why is it important to understand myosin in exercise physiology?

∙Aptness ∙Energetics ∙Implications for power production and performance ∙Fiber typing

What are the key regulated variables in hemodynamic homeostasis?

∙Arterial blood pressure and tissue metabolic homeostasis ∙Blood pressure is determined by 2 factors: →Q = blood flow (cardiac output' primarily regulated by the heart)) →TPR = total peripheral resistance (primarily regulated by vasculature) BP = Q∙TPR ∙Tissue metabolism is regulated in part by blood flow →BP is set systemically →Tissues control their resistance to flow Q = BP/TPR ∙Competing demands for blood flow as tissue metabolism increases during exercise; lower resistance to increase blood flow to working tissue, but systemic resistance needed for blood pressure homeostasis

What is the sliding filament theory of muscle contraction?

∙As cross bridges cycling throughout the sarcomere, the thin and thick filaments slide relative to each other and shorten the sarcomere and hence the myofibril and muscle

How does the profile of the free energy along the reaction coordinate define the thermodynamics and kinetics of the reaction?

∙As long as ∆G<0, the reaction will go forward (exergonic, spontaneous) ∙The rate at which it goes forward is determined by the ∆G+ - enzymatic catalysis reduces ∆G+ and hastens the reaction rate

Why does blood pressure drop across systemic circulation?

∙Because blood flow is conserved in a closed circuit, blood pressure drops across systemic circulation as it encounters tissue resistance

What nutrient is best suited as a substrate for high-intensity activity? What is best for prolonged activity? Explain.

∙CHO are better suited as a substrate for high-intensity activity whereas fat is a better substrate for prolonged activity →CHO has the highest energy per litre O₂, so it has the greatest power →Fat has the highest energy per unit mass, so it has the greatest capacity →Protein has less energy per g from oxidation in the body because the nitrogen is metabolized into ammonia and urea and excreted in urine and sweat

In what bodily processes is carbon dioxide produced? What is the purpose of ventilation and gas exchange?

∙CO₂ is produced in metabolic (TCA cycle, etc.) and non metabolic (bicarbonate buffering) processes ∙Ventilation and gas exchange defend blood gas (arterial Po2, Pco2) and arterial pH homeostasis

What does calorimetry measure?

∙Calorimetry measures heat production and thus metabolism ∙Direct (measures heat) or indirect (measures O₂ consumption) ∙Indirect: gas exchange (VO₂, VCO₂), doubly labeled water

How do valid pre-employment screening tests protect employers from legal challenges of discrimination?

∙Cannot discriminate on basis of age, gender, race, colour, religion, national origin, disabilities ∙Discrimination: use of any selection procedure that has an adverse impact on the hiring or promotion of a defined minority group ∙Adverse impact: four-fifths rule- a selection rate of a minority group less than 80% of the rate fro the group with the highest rate ∙If the job has sufficient physical demands, then the employer must conduct a validation study that demonstrates that the test measure important job behaviours (discriminates, but in a justifiable manner, i.e. on ability to do the job) ∙A candidate who successfully legally challenges a selection is entitled to compensation

What is the role of macronutrients in metabolism?

∙Carbs, lipids, and proteins are catabolized to provide reducing equivalents (e⁻) to the mitochondria ∙Redox reactions reduce equivalents from C-H bonds in macronutrients to electron transport chain in mitochondria (end up with a fully oxidized carbon) →There are reducing equivalents produced and released at each step

What is the affect of body posture on cardiac output?

∙Cardiovascular drift: HR increases during prolonged exercise at same power →EDV progressively decreases, decreased ability to promote venous return (sympathetic NS), blood flow to skin for cooling ∙Orthostatic intolerance: fainting →Prolonged standing- EDV progressively decreases ∙EDV while supine is similar of low and high-intensity exercise ∙While upright, EDV increases with low intensity exercise and may decrease due to limitations to ventricular filling at high HR at high intensity exercise

What are the core concepts of metabolic biochemistry?

∙Catabolic pathways transfer chemical energy from foodstuffs to free energy for: powering ATP synthesis, carbohydrate, lipids, proteins, energy is transferred via redox reactions ∙Control of reactions rates ("flux" through pathways) →thermodynamics- which way will the reaction proceed →enzyme kinetics- how fast spatial compartmentalization and transport (cellular organelles) ∙Properties: flux (power), energy yield (capacity), efficiency

What is the kinetic control dogma of biochemistry? Why is this now considered obsolete?

∙Central Dogma: "Rate limiting" enzymes →May be obsolete because all reaction participants (reactants, products, enzymes, cofactors, etc.) contribute to controlling the flux of the reaction →May still be a useful approximation though because come steps control the overall rate more than others For the reaction: A + E ↔ EA → E + B r= (k(cat)[E][A])/(K(M)+[A]) k(cat)- rate per enzyme K(M)- michaelis constant

What parts of the brain and involved in control of ventilation?

∙Centres in the brainstem control ventilation musculature →Respiratory centre receives diverse feedforward and feedback inputs and innervates the diaphragm & intercostals ∙Basic rhythmicity centre in medulla consists of two centres: →Expiratory: innervated the internal intercostals and abdominals →Inspiratory: innervates the diaphragm and external intercostals ∙Pneumatic centre receives input from lung stretch receptor and facilitates expiration ∙Apneustic centre receives inhibitory input from lung stretch receptor and facilitates inspiration and inhibits the pneumotaxic centre ∙The motor cortex can stimulate both the expiratory and inspiratory centres (modifies the inherent rhythmicity of breathing; speaking, altered breathing patterns like swimming, elevates ventilatory rates in exercise)

What type of work does muscle contraction represent?

∙Chemical energy (ATP hydrolysis) > kinetic energy (myosin conformation change, shortening of muscle)

What is a closed system vs an open system in terms of thermodynamics? What are the 2 laws of thermodynamics?

∙Closed system→exchanges neither matter no energy with its surroundings ∙Open system→exchanges can occur ∙1st Law→energy of the universe is constant (not created or destroyed) ∙2nd Law→all processes incase entropy

Outline the MU recruitment during dynamic (an anisometric) contractions.

∙Compared to isometric contractions, force thresholds and firing frequencies are lower and higher, respectively, for Isotonic contractions Isovelocity contractions Ballistic isometric contractions (hard as you can right away) ∙High velocity contractions: the speed at which a muscle needs to relax also determines which motor units are recruited; important for repetitive cyclical movements Faster MU's have faster relaxation kinetics (Ca²⁺ uptake) (Violates the size principle) ∙Lengthening contractions involve different neural strategies MU pool is less active overall Size principle is generally adhered to

Define "contractility" in terms of the heart.

∙Contractility is the quality of ventricular performance for given loading conditions and heart rate →The strength of cardiac contraction (for a given EDV) depends on availability of Ca²⁺, which in turn determines # of cross-bridges

Why does body temperature increase during exercise?

∙Contracting muscle generates heat which has massive implications on exercise tolerance

How do you measure the physiological strain from heat exposure?

∙Core temperature: rectal, tympanic, sublingual, esophageal, temperature pill- gastrointestinal ∙Skin temperature: dermal temperature patch ∙Sweat rate

Describe the training induced cardiac adaptations.

∙Decreased resting and sub maximal exercise heart rate (bradycardia) ∙Increased stroke volume ∙Altered electrocardiogram: AV blocks, wandering atrial pacemaker, AV nodal pacemaker rhythm, ST segment elevation, PVC's, T wave inversion ∙Increased prevalence of third and fourth heart sounds ∙Improved calcium release and transport

What is the relationship between oxygen consumption and energy liberated (kcal)?

∙Depends on the foodstuffs metabolized ∙Respiratory quotient (RQ)= VCO₂ produced/VO₂ consumed, as determined by the chemical reaction; reflects cellular processes →Carbohydrate= 1.0 →Lipid (much lower oxygen that carbs)= 0.71 →Protein= 0.80 (we don't fully oxidize our proteins, you break them down into ammonium and urea) ∙For a given amount of O₂ consumption, you get more energy from carbohydrate than fat...but you have very little CHO stored compared to fat and it has a lower energy output

How do we interpret and use data on muscular demands of a job?

∙Develop performance standards, propose exposure limits for MMH tasks, and estimate worker physiological strain

What are the approaches to evaluating muscular demands on the job?

∙Direct: weight loads lifted, use equipment to measure force (N) during the activity, force matching (worker is asked to recreated force of a task on a dynamometer using similar posture and had position, usually immediately after performing the actual task itself) ∙Physiological/EE based: measure HR or EE during MMH tasks ∙Estimation based on observation and worker self-report

How is the force output of a motor unit controlled?

∙Discharge frequency (twitch, unfused tetanus, tetanus) ∙Rate Coding: the force of a muscle fibre, motor unit, or muscle depends on the frequency of stimulation (fast motor units would be capable of producing quite a bit more force than the slow motor units)

Why can't excess post-exercise oxygen consumption (EPOC), aka. oxygen debt, be used to infer anaerobic energy contribution?

∙Disregards EE during recovery ∙Metabolism higher due to increased temperature →EPOC is the O₂ consumption during recovery from intense exercise

What are the 3 ways in which carbon dioxide is transported in the blood?

∙Dissolved (~5-7%) ∙Bound to protein (~25%) ∙As bicarbonate (chemically reacts with water to form carbonic acid, which dissociates to bicarbonate (catalyzed by carbonic anhydrase in RBC's; ~70%) →Bohr effect: H⁺ drives O₂ unloading

Briefly outline the thermodynamics of glycolysis. (ie. the free energies)

∙Driving force exists for glucose catabolism ∙The standard free energy of product is less than the starting reactant ∙The products are transported to other compartments: [substrates] > [products] →There are some uphill reactions in glycolysis but they are powered by being coupled and the overall reaction is downhill

Briefly outline the thermodynamics of the TCA cycle.

∙Driving force for pyruvate oxidation ∙Overall net decrease in free energy (in terms of standard free energies)

What types of equipment are used for directly measuring forces and torques of job tasks?

∙Dynamometers: devices for measuring force, torque, or power ∙Push-pull force gauges

In what circumstances would ventilation rate/minute ventilation be a better predictor of work rate than heart rate?

∙HR is sensitive to environmental factors and others such as psychological stress →Ve works better at low intensities because stroke volume eventually hits a plateau →HR is better at high intensities

What is excitation contraction coupling? What feature of skeletal muscle cells in particularly important for this process?

∙EC Coupling: the mechanism by which the action potential triggers Ca²⁺ release and subsequent contraction →Ca²⁺ triggers muscle contraction by binding troponin and causing a conformational change that shifts tropomyosin away from myosin binding sites on actin ∙Transverse tubules (T tubules) are extensions of the sarcolemma that penetrate into the fibre and lie adjacent to the Ca²⁺ storage site *the internal cisternae of the sarcoplasmic reticulum) →Terminal cisternae contain calcium ∙Sarcoplasmic reticulum is a membranous bag surrounding each myofibril that stores, releases, and pumps back Ca²⁺

What are some practical approaches to energy expenditure estimation?

∙EE estimation for exercise on common ergometers: ACSM prediction equations →measure has exchange (VO₂, VCO₂) on a sample of humans performing physical activities at specified intensities →estimate EE via conversion eons →fit a regression eqn to predict VO₂ from ergometer parameters ∙EE estimation of physical activities: compendium of physical activities →measures gas exchange (VO₂, VCO₂) on a sample of humans performing physical activities at specified intensities →estimate EE via conversion eqns →tabulate the activity and its intensity along with the average EE →VO₂ is expressed at Metabolic Equivalents (METs)= multiples of average resting VO₂ (3.5mL kg⁻¹min⁻¹)

How is a surface EMG signal generated?

∙EMG electrodes are on the surface of the skin ∙Depolarization at the NMJ sends muscle action potentials propagating in either direction along fibers with certain conduction velocity ∙AP's of the fibres sum to form the "motor unit AP" (MUAP) that is detectable at the skin surface ∙The signal propagates under electrodes and is detected; the potential difference between the electrodes is displayed ∙Many such signal are generated when multiple AP's are elicited in the muscle, which appear as bursts with different amplitudes and frequencies

During high-intensity cycling to fatigue, it is reported that the integrated EMG measured using surface EMG progressively increases and that this increase reflects additional motor unit recruitment. Discuss the merits of this interpretation. Describe how you could verify or refute this interpretation using biochemical techniques.

∙EMG is useful but limited and so are the biochemical techniques

How do we estimate efficiency?Why is efficiency/economy so important to sports?

∙Efficiency is estimated by plotting energy expenditure vs. power from steady-state efforts at increasing powers (similar method to the one used for the accumulated oxygen deficit) ∙Efficiency/economy (ie. the ability to convert metabolic power into mechanical power) is a critical determinant of performance →For a given VO₂, the person who is more efficient will be able to produce a higher power output

What are 3 scientific techniques for studying motor unit recruitment?

∙Electromyography →Surface (noninvasive): bipolar electrodes (most common), linear array →Intramuscular or needle (invasive): implant indwelling fine-wire electrodes into muscle; can distinguish individual motor unit activities with this way ∙Muscle biochemistry (biopsy) →Glycogen depletion →PCr:Cr ratio (as muscles contract, PCr will ↓ because it is being buffered) ∙Imaging →MRI →Positron emission tomography →Near infrared spectroscopic imaging

Why would an employer want to implement pre-employment physical abilities testing?

∙Employers want employees who can competently perform the (physically demanding) job without undue risk of harm ∙Economic reasons: reduced injuries & workers compensation costs, reduce employee turnover & associated costs, avoid legal challenges & compensation costs ∙Worker safety and productivity

Compare cardiac hypertrophy for endurance, weight-trained, and diseased hearts.

∙Endurance trained: →Flow work, "concentric" hypertrophy →Sarcomeres added in series →Ventricle dimensions increase →Ventricle walls increase thickness →Some lifelong athletes: fibrosis, atrial fibrillation ∙Weight-trained: →Pressure work (ex. Valsalva manoeuvre), "eccentric" hypertrophy →Sarcomeres added in parallel Ventricle walls thicken but dimensions same ∙Disease: hypertension (↑ after load) + coronary artery disease (less O₂) →Connective tissue added to heart to lessen wall stress →Little increase in functional capacity

What is the importance of elastic elements in myosin and the thick filament?

∙Energetics are different for isometric, concentric, and eccentric contractions ∙Sliding filament theory is intuitive for concentric but not isometric or eccentric contractions ∙Myosin molecules and those of the thick filament are elastic and can stretch, thus enabling the cross bridge cycle to occur and to generate tension without necessarily shortening the muscle ∙Eccentric contractions: pulling forces on the actomyosin complexes causes them to dissociate without hydrolysis of the bound ATP; A & M rebind and resist further pulling; thus force is generated without EE (more efficient than concentric)

Define "energy expenditure ."

∙Energy Expenditure→ the total amount of energy (gross) expended during exercise, including the resting energy expenditure (resting energy expenditure + exercise energy expenditure). Energy expenditure may be articulated in METs, kilocalories, or kilojoules.

What is the principal controller of metabolism?

∙Energy Flux →Homeostasis during exercise: match energy supply to demand →Turnover of ATP creates driving force for upstream flux all the way from glycogen →Glycogen phosphorylase is activated by covalent modification through epinephrine signalling →BUT epinephrine signalling without ATP demand does not cause (much) glycogenolysis vs. electrical stimulation with no hormonal changes: glycogenolysis occurs

What are the basic principles of bioenergetics? Explain.

∙Energy→ is the capacity to do work ∙Work→ transfer of energy by means other than heat (Mechanical): product of force acting through a given distance →Also chemical, electrical, osmotic work

How might you establish standards of acceptable performance and cut scores for a pre-employment physical abilities test?

∙Have incumbent workers perform the test and measure their times-to-completion (they can do the job so they should be able to do the test) ∙Cut scores should: be reasonable and consistent with normal expectations of acceptable proficiency within the work force, optimize "sensitivity" and "specificity" but minimize degree of adverse impact, be sufficiently high to ensure minimally accepted job performance →Want people who can do the job to pass and people who can't to fail →False positive= pass test but can't do job →False negative= fail test but can do job

How is the flux of a metabolic reaction controlled? What are the mechanisms in control of this?

∙Enzymes control flux (mol converted per unit time) of metabolic reactions by lowering the activation energies of the reaction ∙Mechanisms controlling enzymes: →Enzyme activity: mol of substrate converted per unit time per molecule of enzyme (higher activity=higher potential flux through the pathway) →Enzyme [ ]: overall enzyme activity is directly proportional to the amount of enzyme in the system, control is at level of gender expression →Covalent Modification: enzyme is post-transitionally modified through the attached of a chemical moiety one of its amino acid residues (ex. phosphorylation, acetylation, methylation, etc.)∙ Allostery: molecule binds to enzyme somewhere OTHER than the catalytic sit; alter enzyme's activity be changing its conformation ∙Competition, product inhibition

How do you increase the reaction rate in biochemical reactions? Why is this important?

∙Enzymes! ∙By binding noncovalently to the substrate, the enzyme reduces the energy needed by the substrate to achieve its transition state ∙Virtually all reactions in the cell are catalyzed by an enzyme ∙Kinetics is VERY important for power production (and so is thermodynamics)

What are the steps in developing a job-simulation task circuit that elicits similar physical and physiological demands as the job itself?

∙Establish the design criteria ∙Draft the test ∙Conduct pilot testing and gather feedback ∙Refine test ∙Develop standardized protocol ∙Establish reliability and validity of the test

What are the ways in which ventilation could affect ("limit") exercise performance?

∙Exercise-related transient abdominal pain (ETAP; "side stitch") →Sharp pain in side during exercise, limits ventilation and performance ∙Ventilation requires muscular action and contributes to energy demand ∙Airway flow limitations ∙Breathing requires muscular work and thus consumes energy and contributes to the task demand ∙Arterial desaturation is observed in some highly trained athletes (evidence of limitation in ventilation?)

What are the 3 ways in which ventilation could affect ("limit") exercise performance?

∙Exercise-related transient abdominal pain (ETAP; "side stitch") →sharp pain in side during exercise, limits ventilation & performance ∙Ventilation requires muscular action and contributes to energy demand →the muscles of breathing consume energy, thus contributing to the task demand, and can get fatigued (ex. external intercostals, internal intercostals) ∙Flow limitations →arterial desaturation is observed in some highly trained athletes (evidence of limitation in ventilation)

What does the oxygen dissociation curve tell us?

∙Explains the co-operative binding of oxygen to hemoglobin ∙Starts out shallow because it is hard for O₂ to bind Hb, but then quickly steepens because O₂ bound increases the affinity for more O₂ to bind, and then plateau's as the Hb saturates

How are thresholds associated with quantitative differences in VO₂ kinetics?

∙First Threshold: slow component emerges ∙Second Threshold: VO₂max achieved (ie. no steady state) →Exercise at different intensities within the severe domain leads to same VO₂max, but are achieved at different durations (harder the exercise is, the faster you will end up at VO₂max)

How do we detect and characterize ventilatory limitations during exercise?

∙Flow volume loops ∙MFVL: Maximal flow-volume loop (or "envelope") is the reference maximal flow volume loop is determined by the participant executing several maximum inspiratory and expiratory manoeuvres ∙MFVL= loop from manoeuvre with largest FEV1 (max flow) and FVC (max volume) ∙extFVL: tidal exercise flow volume loop ∙EILV: end inspiratory lung volume ∙EELV: end expiatory lung volume

How is glycogen phosphorylase controlled? (enzyme in glycogenolysis)

∙Flux through phosphorylase is controlled by: →Substrate control: glycogen availability, adenine nucleotides →Phosphorylase catalytic activity: concentration of phosphorylase, signalling via phosphorylation, Ca²⁺, hormonal signalling (ex. of neuroendocrine control of metabolism) →Allostery: AMP binding

How does heat production and oxygen consumption provide measures of metabolic rate (EE)?

∙For a body at rest, all biochemical reactions eventually lead to heat production (not true for an exercising human because you are doing external work on the environment) ∙For low power activities, oxidative processes supply virtually all energy needed for ATP generation; hence, oxygen consumption is directly related to energy expenditure (if you can measure heat and oxygen, you can measure energy of metabolism)

What are the major energy consuming processes in muscle contraction?

∙Force production through cross bridge cycling ∙Calcium sequestration ∙Sustaining membrane potential

What are some applications of muscle structure to exercise physiology?

∙Geometry contributes to the ability to produce force ∙Muscle structure will change with resistance training (hypertrophy; satellite cell activation and integration) ∙Importance of other cell types in muscle repair & regeneration ∙Flexibility is part muscle but also neural and fascial

What are some biochemical techniques for assessing recruitment?

∙Glycogen depletion (tissue sections) →Measured using Periodic Acid-Schiff (PAS) staining, Use histochemistry on serial sections to match glycogen depletion with fibre type, Glycogen=stored glucose, Recruitment of muscle fibre consumes glycogen, Glycogen depletion not immediately observable; recruitment may not be immediately evident ∙Phosphocreatine (PCr)-Creatine (Cr) ratio in single fibres →Measure PCr & Cr [ ]'s in single fibres; use immunological techniques to determine the fiber type, PCr reaction: ADP + PCr ↔ ATP + Cr [creatine kinase], PCr buffers ATP, Fast kinetics: [PCr] is immediately responsive to energetic demand but recovers quickly (so one has to be quick on excising the biopsy)

What is glycolysis? Where does it take place?

∙Glycolysis= dissolution of glucose ∙Occurs in cytosol

How might enzymatic activity be controlled in glycolysis?

∙Glycolytic enzymes may be localized to Z-disc, proximal to reactants and products ∙Enzyme [ ]'s, isoforms, and allosteric control (ex. lactate dehydrogenase is inhibited by ATP) ∙Enzyme concentration: fast twitch muscle fibres, typically feature higher levels of glycolytic enzymes

Why is the "energy-systems view" of training not physiological justifiable?

∙It is common to examine exercises in terms of the dominant energy system (ATP-PCr, Glycolysis-lactate, oxidative) ∙"Specificity" principle dictates that training should work the systems important to the goal task (ex. if you are training for an anaerobic sport, you would train the ATP-PCr and glycolysis systems) →ALL of these pathways have flux through them all the time →No clear direct link between flux through these pathways and gene expression changes (for fitness-promoting adaptations to occur, you NEED to have gene expression changes →The muscle-recruitment-centric viewpoint arrives at similar answers but within a more physiologically coherent framework

What does a typical pre-employment physical abilities test involve? What are the advantages and disadvantages to this?

∙Job simulation tasks, sometimes combined with tests of one or more fitness components, typically aerobic fitness ∙Advantages: relatedness to job=higher acceptance by workers/stakeholders/courts, can be combined into a circuit, challenge all of the fitness components relevant to the job ∙Limitations: may not effectively evaluate aerobic fitness; extending its duration may detract from its relatedness to the job→ aerobic fitness sometimes tested separately ∙Applicant screening: aerobic fitness test + job simulation circuit ∙Annual incumbent testing: job simulation circuit with embedded aerobic fitness requirement

Explain the force-velocity relationship for muscle performance.

∙Lengthening is on the left side, shortening is on the right ∙Eccentric > concentric; faster eccentric > slower eccentric →Eccentric contraction- you can put out more force than isometric and concentric. It is also the most energetically efficient

Give a brief overview of lipid oxidation during exercise.

∙Lipids are mostly non polar compounds that dissolve in organic solvents but not water ∙Beta-oxidation results in fatty acid oxidation: each cycle produces: 1 NADH + H⁺, 1 FADH₂, 1 acetyl-CoA per two carbons ∙Energy yield (sum of yields from beta oxidation and TCA cycle): (ex. for palmitate, 16C) = 129 ATP

What is glycogenolysis?

∙Lysis of glycogen ∙Glycogen consists of glucose units linked in linear and branched manners (heavily hydrated/associated with water...so if you deplete glycogen, you lose lots of water) ∙Controlled by the activity of phosphorylase (rate limiting enzyme)

How is the electron transport chain mainly controlled?

∙Mainly controlled through feedback mechanisms →ATP and ADP are the primary controllers of the ETC →Also NAD⁺ vs. NADH and O₂ availability ∙During exercise: →[ATP]:[ADP][Pi] ratio decreases →[NADH]:[NAD⁺] ratio decreases ∙ADP is the primary determinant of mitochondrial O₂ consumption

What are 3 non invasive ways to estimate anaerobic capacity? Why would you want to assess anaerobic capacity?

∙Maximal accumulated O₂ deficit ∙Gross efficiency (not commonly used) ∙W' from the critical power model →Anaerobic capacity is a property of your performance profile, can be modified (but not very easily) →Guides training

What is the gross efficiency method of assessing aerobic and anaerobic contributions to mechanical power?

∙Measure VO₂ and power output ∙Aerobic contribution to mechanical power= VO₂ x ~5kcalL/O₂ x efficiency for anaerobic energy transfer ∙Anaerobic contribution= power output - aerobic contribution

What is metabolism and what are its units of measurement?

∙Metabolism: sum of all transformations of energy and matter that occur within an organism ∙Measured in: →Calorie (heat required to raise temperature of 1g of H₂O 1°C →Kilocalories (1000 calories) →1 Joule= 1 N∙m= 1 kg∙m⁻²s⁻² →1 cal= 4.184 J

What is a microvascular unit? How do we measure capillarity?

∙Microvascular unit: capillaries emanating from a common arteriole and ending in a common venue ∙Capillarity is measured: 1. # of adjacent capillaries per fibre →Limitation: capillaries are shared by multiple fibres; Typical value: 4 capillaries per fibre in mammals) 2. Capillary Density: capillaries per square millimetre of cross-sectional fibre area →Limitation: changes in CSA can alter capillary density rather than capillary number; Typical value: 500 capillaries mm⁻² for fibre CSA of 4000 micrometers² to 900 for CSA of 1250 micrometers² 3. Capillary-to-muscle-fibre ratio: least prone to misinterpretation →Typical value: 2 capillaries per fibre, increased by exercise training (humans 5-20%/8-12 weeks of endurance training; rodent= chronic low frequency stimulation of fast muscle, 55%)

In glycolysis, the steps that consume ATP and generate ATP are all exergonic. How can this be?

∙Molecules that have higher free energy than ATP can supply the free energy to make ATP (but then ATP is in the middle so it can be created by exergonic reactions and has high enough free energy to power other reactions)

What does it mean for a muscle to "contract?" What is a twitch? What are the contractile properties of muscle?

∙Muscle "contraction:" activation of the force generating capacity of the actomyosin complex within fibres and initiation of the four-step crossbridge cycle (more than 4 steps now) ∙A "twitch" is the muscle force profile resulting from a single stimulus ∙Contractile properties: max force, time-to-peak tension (TPT), half-relaxation time (duration from max tension to 50%, ie. how fast the SERCA pumps can bring calcium back into the SR)

How do we analyze human muscle cellular and molecularly?

∙Muscle biopsies! ∙Homogenize: grind up & solubilize, isolate desired molecules (proteins/lipids/carbs/nucleic acids), enzyme activity assays, detection & qualification of specific molecules ∙Tissue Sections: freeze/cut tissue sections in a cryostat, embed in paraffin wax/cut sections, mount sections on glass slides, process for histochemistry, serial sections (often get more than one slide containing the same fibre so you can stain for different things) ∙Isolate Single Muscle Fibers: freeze dry and dissect individual fibres from the biopsy

Given what we know about MU recruitment, what are some training techniques for muscular strength/endurance? Neuromuscular training? Rhythmic movements of large proportions of muscles?

∙Muscular Strength: resistance training, ballistic exercises, plyometrics ∙Neuromuscular Training: stretching, balance/agility, sport-specific techniques/drills ∙Rhythmic Movments: submit moderate intensity, recovery, tempo, threshold intervals, severe intensity intervals, repeated sprint training, spring intervals, max sprinting

What are the two predominant contractile proteins in a skeletal muscle fiber?

∙Myosin (thick filament, A band) ∙Actin (thin filament)

Differentiate between physical activity, exercise, and physical fitness.

∙Physical activity→ and bodily moment produced by skeletal musculas that results in energy expenditure above resting levels. It encompasses exercise, sports, and physical activities done as part of daily living, occupation, leisure, and active transportation ∙Exercise→ physical activity that is planned, structured, and repetitive and that has a final or immediate objective the improvement or maintenance of physical fitness ∙Physical fitness→ the ability to carry out daily tasks with visor and alternates, without undue fatigue and with ample energy to enjoy leisure pursuits and to meet unforeseen emergencies

Explain the concept of power.

∙Power is rate of work, or work/time ∙It is the rate of energy transfer (work/time, force x velocity) ∙Maximum sustainable power determines performance →Power is the main way to quantify physical activity (the fitter you are, the more work you can do at a faster rate)

Define: power, capacity, and efficiency. What is the difference between maximal aerobic capacity and maximal anaerobic power?

∙Power: rate of work ∙Capacity: total work done, irrespective of time ∙Efficiency: ratio of energy output to input (mechanical work/metabolic energy) Maximal Aerobic Capacity: maximal rate of oxygen consumption, VO₂max should be maximal aerobic power (??) Maximal Anaerobic Power: maximal rate at which ATP is resynthesizes via anaerobic metabolism (by the whole organism) during a specific type of short-duration, maximal exercise

How is VO2max a determinant of endurance performance?

∙Power=VO₂max x %VO₂max x efficiency ∙Physiological model of endurance performance: %VO₂max is the faction of VO₂max that can be sustained at a given sub maximal power; it is likely determined by peripheral metabolic factors →Efficiency (economy): is the ratio of the mechanical power output to the metabolic power input ∙VO₂max is correlated with endurance performance when assessed in a broad heterogenous sample (ex. sedentary to trained people) ∙VO₂max is a poor predictor of performance in a homogeneous sample (ex. elite endurance athletes)

What are some applications of job analyses and physical demands analyses?

∙Pre-employment physical abilities screening: identify what prospective workers must be capable of doing ∙Rehabilitation-Job reDesign: compare with functional capacity (or abilities) evaluation of the rehabilitated worker to determine what parts of the job the worker can perform →Work hardening: train the worker so capabilities meet or exceed those needed to do the job

What are the four principle factors that affect cardiac performance during exercise? How are they regulated?

∙Preload (End Diastolic Pressure): Q, posture, venous tone, blood volume, priming by atria, muscle pump, intrathoracic pressure ∙Afterload (Resistance from periphery): sympathetic and parasympathetic impulses, static muscle contraction, anatomical impedance, intrathoracic pressure ∙Contractility (Strength of cardiac contraction): loss of myocardium, inotropic drugs, pharmacological depressants, force-frequency relation, sympathetic and parasympathetic impulses, Ca²⁺-ATPase activity, circulating, catecholamines ∙Heart Rate (Frequency at which heart beats): sympathetic and parasympathetic impulses, catecholamines, chronotropic drugs)

When and where does complete oxidation of pyruvate occur?

∙Proceeds in mitochondria via the TCA cycle and the electron transport chain →TCA cycle= tricarboxylic acid cycle/krebs cycle/citric acid cycle (generated reducing equivalents) →Electron transport chain= reduces O₂ and liberates free energy for ATP synthesis

How is the shape of a skeletal muscle action potential a result of the ion conductances?

∙Rapid upstroke caused by opening of Na⁺ channels and Na⁺ influx ∙There is fast inactivation of these channels and the increasing membrane potential causes the opening of K⁺ channels ∙The repolarization is a result of buffering by Cl⁻ flux

What is reactive hyperemia? What is local autoregulation?

∙Reactive Hyperemia: surge in blood flow following compression of vessels in contracting muscle ∙Local autoregulation: vascular smooth muscle is stretch sensitive →↑BP: vasoconstricts →↓BP: vasodilates

What does the arteriovenous oxygen difference tell us for an exercising person? How do we calculate a-vO2 difference?

∙Reflects oxygen extraction by tissues→ not all the oxygen in arterial blood is extracted by the tissues; venous blood contains oxygen a-vO₂ difference (mL O₂ 100mL⁻¹= vol%) = difference in Cao₂ between arterial and venous blood →Reflects the amount of O₂ extracted by the tissue →u # of mitochondria, transit time, diffusion rate of O₂ (Hb, oxy-Hb dissociation curve, myoglobin)

What is the epidemiological evidence supporting pre-employment physical testing?

∙Relationship between injury risk and percentage of strength capacity used by worker in job performance (If you have a stronger worker, they are working at a lower % of their max load and are at less risk of injury)

How would you directly measure anaerobic energy contribution during exercise? What assumptions are made?

∙Requires muscle biopsies before and after exhaustive exercise ∙Use an equation developed on dry muscle to calculate anaerobic ATP yield →Does not account for lactate released into blood & oxidized elsewhere, often used in conjunction with occlusion →Inferring whole-muscle anaerobic ATP yield, assume biopsy results can generalize over the muscle mass of the prime movers →Inferring whole-body anaerobic ATP yield, assume % body mass of muscle activity (~25% for high-intensity exhaustive cycling protocol used in study)

What is afterload? How does exercise affect this?

∙Resistance the heart meets as it attempts to pump blood into the circulation ∙Exercise involving Valsalva manoevre ; hypertension- increases afterload

How can oxygen consumption and RER measurements be used to infer EE?

∙Respiratory gas exchange ratio (RER or R)= VCO₂/VO₂ measured at mouth via has exchange (same as respiratory quotient, RQ; reflects cellular processes) measurements ∙RQ=RER, under certain conditions, over a prolonged time (ie. low intensity steady-state exercise) →There is non metabolic CO₂ production from buffering of protons in the blood which is why RQ is not the same as RER (High intensity exercise-↑[H⁺]) ∙A delay exists btwn cellular events and gas exchange at lungs ∙Exercise: VCO₂ in mouth is higher due to non metabolic CO₂ production (buffering) + storage of CO₂ in cells at onset ∙Recovery: VCO₂ in mouth is lower due to replenishing of HCO₃⁻ reserves

What are the types of respiratory training? Can training of respiratory muscles improve endurance performance?

∙Respiratory muscle strength training: →High force, low velocity contractions induced by breathing against external load that consists either of a flow-dependent resistance or a pressure threshold that must be overcome to initiate flow ∙Respiratory muscle endurance training: →Low force, high velocity contractions generated by voluntary hyperpnea (increased rate and depth of breathing) ∙Endurance performance= incremental tests, time trials, or constant-load tests →Yes, particularly in less fit participants (effects of strength vs. endurance training were not different

What are the components of total energy expenditure?

∙Resting EE: energy requirement of an awake, resting person measured 8-12 hours after email (post-absorptive state) or exercise →~70% of daily EE, proportional to body mass →vs. basal metabolic rate: measurement taken upon waking after sleep & fasting (BMR will be slightly lower than RMR, the heavier you are the higher your RMR) ∙Thermal effects of foods: heat produced by digestive processes →energy costs of digestion: protein>CHO>fats (5-10% of daily EE) ∙Thermogenesis: heat produced unaccounted for by other components →cold exposure, stimulants, psychological stress (~15% of daily EE) ∙Physical-activity-associate EE (PAEE): EE above basal level from any bodily movement produced by the contraction of skeletal muscle →highly variable: ~1800kcal sedentary to ~6000kcal athlete *The only thing you can do to lose weight is control the PAEE- important to do resistance training to maintain RMR by increasing the amount of muscle tissue

Give a general overview of the anatomical structures of skeletal muscle (from cell to organ).

∙Sarcomere ∙Myofibril (sarcomere in series) ∙Muscle fibre/skeletal muscle cell/myocyte (bundle of myofibrils in parallel) ∙Fascicle (bundle of muscle fibres in parallel, tens) ∙Muscle (tissue/organ level) (bundle of fascicles in parallel)

Besides myocytes, what other types of cells are in muscle tissue? Describe the geometry of muscle tissue.

∙Satellite cells: adult stem cells that can differentiate into myoblasts>myotubes (ie. immature muscle fibers)>adult muscle fibres →Crucial for muscle regeneration, repair & training adaptations! ∙Immune cells ∙Connective tissue cells (ex. fibroblasts) →Important to muscle damage resolution ∙Adipose cells ∙Muscle cells are multinucleate (nuclei reside on surface fibre, ~200-300 nuclei/mm fibre) ∙Geometry of the tissue (ex. pennation), interface with connective tissue

How do reducing equivalents move to the mitochondria? How are they transferred across mitochondrial membranes? How does this affect ATP yield?

∙Shuttled to mitochondria using specialized carriers: NAD⁺ (accepts 1H⁺ + 2e⁻) and FAD (accepts 2H⁺ + 2e⁻) ∙Transferred across mitochondrial membranes by two transport systems: malate-aspartate shuttle, glycerol-phosphate shuttle ∙ATP yield depends on which carrier is used: →NADH= 3 ATP →FADH2 enters electron transport chain later, so only provides sufficient free energy to synthesize 2 ATP

What is a protein isoform? Describe a protein isoform involved in muscle contraction and describe its effect on the energetics of contraction.

∙Similar protein with variations in their amino acid sequences that may modify their functional properties →Actomyosin ATPase (type I, IIa, IIx, IIb) →Rates are higher for shortening contractions compared to isometric

What is the critical power model? What does it tell us?

∙Simple model of the power-duration relationship; its parameters are critical power (CP) and W' ∙CP= maximum sustainable power (theoretically for infinite time) →Physical interpretation: maximal power that can be sustained solely by aerobic energy supply ∙W' used to be called "anaerobic work capacity" (still a major contributor to the energy available for work) →Physiological basis of W' is multifactorial; it is better defined as the energy available for work above CP until the limit of tolerance

How might performing a warm up affect VO₂ kinetics in subsequent exercise? Discuss what intensities of warm up exercise out to be employed.

∙Speed O₂ kinetics ∙If you wanted to speed up O₂ kinetics, you would work at a low intensity so as to not deplete substrates (also want a rest person between warm up and real performance)

Explain the change in oxygen uptake as it relates to time?

∙Steep increase in exercise intensity signals a delayed increase in oxygen uptake (~2mins; results in O₂ deficit- whenever you chang exercise intensity you "dig a bit of a hole," but you can catch up ∙The delay in increased oxygen uptake is a result of the signalling mechanisms taking time to increase ventilation and start delivering more O₂ in the blood →The inertia of oxidative metabolism means that anaerobic sources must be used: faster kinetics would limit fatigue & improve exercise tolerance

How is VO2max an index of cardiovascular health and function? How do we determine VO2max for the average population?

∙Stress tests are graded exercise tests that measure VO₂max and use ECG to assess heart electrical function ∙Properties of graded exercise tests: →must use >50% of muscle mass →continuous, rhythmical →not rely on skill or motivation →standardized conditions (temperature, humidity, pollution, altitude) ∙Judging whether VO₂max was actually achieved: →perceived exertion (exhaustion) →RER >1.1 →[lactate] > 8mM →peak HR = 220-age ∙Upper body exercise modalities are not suitable for determinations of VO₂max (local fatigue = ~70% of treadmill measured VO₂max) →Cycling is the most commonly used modality but ~85% of treadmill measured VO₂max (it is very specific to the activity)

What are some general measurement techniques for physical demands analysis?

∙Subjective/observational →Direct observation, video analysis, questionnaires ∙Endurance →Portable gas exchange and ventilation, heart rate, activity monitors ∙Muscular →Scale, tape measure, force gauge, push/pull dynamometer ∙Tolerance to environmental factors →Wet-bulb globe thermometer, surface and core temperature monitors, sweat rate monitors ∙Integrated →Portable multi parameter physiological monitors

How does the location of a mitochondria affect its function?

∙Subsarcolemmal: positioned near sarcolemma, likely supply energy for ion and metabolite transport ∙Intermyofibrillar: positioned between myofibrils, likely supply energy for myosin ATPases **Mitochondria are not isolated organelles but instead form a "reticulum" (interconnected network)

What are the control mechanisms of the TCA cycle flux?

∙Substrate availability ∙Requirement of oxidized coenzymes ∙Allosteric inhibition of early enzymes by the reaction products ∙Ca²⁺, AMP, ADP= activators ∙ATP, NADH, succinyl-CoA= inhibitors ∙Isocitrate dehydrogenase= "rate-limiting"

How is the heart and vasculature controlled in a "whole-body" sense?

∙The autonomic nervous and endocrine systems control the heart and vasculature to effect blood pressure regulation →The heart, arteries, arterioles, venues, and veins are sympathetically innervated ∙Hormones: (adrenal medulla) epinephrine, norepinephrine ∙Cardiovascular control centre integrates various sensory inputs and coordinated the responses (CCC= a loose collection of neurons in the reticular formation of brain stem (mainly in pons and medulla) ∙Central command controls heart rate and left ventricular contractility by controlling efferent sympathetic (+) & parasympathetic (-) nervous system signals

What is the purpose of the electron transport chain? What are the yields of ATP from the reducing equivalents?

∙The electron transport chain transfers free energy from reduction reactions to pump H⁺ and generate proton-motive force, the potential energy of which is then converted to free energy to drive the ATP synthase →accepts reducing equivalents (e⁻) from NADH + H⁺ & FADH₂ and transfers them to O₂ while pumping H⁺ to create proton-motive force →H⁺ are transported into the intermembrane space, flow back into matrix through ATP synthase →ATP is generated on the matrix side, transported via adenine nucleotide transporter ∙Yield from reducing equivalents: →1 NADH + H⁺= 3 ATP →1 FADH₂= 2 ATP (due to entry point in ETC) →O₂ is the final e⁻ acceptor →P:O ratio expresses the efficiency of ATP generation with respect to oxygen atoms (P:O=3 for NADH-linked substrates, P:O=2 for FADH₂-linked substrates →~6 mol of ATP per 1 mol O₂

What is bioenergetics? What does it consist of?

∙The science of energy transductions in biological systems ∙"Understanding what energy is and how the body acquires, converts, stores, and utilizes it is the key to understanding how the body performs in sports, recreational, and occupational activities" ∙...applied physical chemistry (thermodynamics, kinetics) →Thermodynamics: whether a reaction will occur and its direction →Kinetics: the rate at which the reaction occurs

What is the "slow component" of VO₂?

∙The slow component of VO₂ is the continued rise of VO₂ beyond the primary phase ∙Delayed onset (~180-360s) ∙Features slow kinetics relative to those of Phase II ∙Takes several minutes to achieve steady state ∙Is ~10-20% of total VO₂ (decreasing your efficiency by that amount by default) ∙Arises during heavy intensity exercise (or above) ∙Tends to be less in treadmill running than other modalities ∙Importance: it reduces efficiency/economy, it reduces %VO₂max that can be sustained due to increased substrate depletion ∙Mechanism is no yet fully understood, Hypothesis: →loss of efficiency within working muscle/reduced free energy of ATP (need more ATP for a given task demand, need more O₂ for oxidative phosphorylation) →additional recruitment of higher-threshold motor units whose muscle fibres are less metabolically efficient (and thus contribute to O₂ uptake)

What is the theoretical yield of ATP at the end oxidation of glucose and glycogen via the TCA cycle.

∙Theoretical yield is 36 or 38 ∙Actual yield is less due to leaks in the system (uncoupling), probably around 30 because some protons escape and don't transfer free energy

Why can't running form or technique be used to predict economy?

∙There are many determinants of running economy ∙Ex. metabolic efficiency (ex. Type II fibres are less efficient), cardiorespiratory efficiency, training, biomechanical efficiency, neuromuscular efficiency (stiffness of the "spring" your legs create when you're running) →All of these factors are mediated by genetics

Explain the muscle fibre length-tension relationship.

∙There is an optimal range of sarcomere length to have the perfect filament overlap

Motor units and fibres are classified into discrete categories based on their properties. Do you expect no overlap, some overlap, or significant overlap of properties for motor units from different categories?

∙There is some overlap of motor units from different categories →Fibres and muscles tend to express specific isoforms predominantly according to their function, but there are many distributed properties

What are some of the factors that can affect the strain felt by workers?

∙Thermal (hold/cold) ∙Vibration ∙Noise ∙Disruption of circadian rhythms (shift work, travel)

How does blood transit time near alveoli change with exercise?

∙Time blood spends in the alveolar capillaries provides time for the gases to equilibrate with passing blood →Transit times decrease with exercise intensity due to faster blood flow; can be limiting in elite athletes at high intensities (transit time might not be enough and can cause arterial desaturation) →In normal conditions, there is plenty of transit time

How is tissue capillary blood flow controlled?

∙Tissue capillary blood flow is mainly controlled by vasoconstriction and vasodilation of proximal arterioles, which alter the vessel radius and determine the resistance to flow Q= (P₂-P₁)pi∙r⁴/(8Ln) →Small changes in r cause big changes in Q because it is raised to the power of 4 ∙Endothelial cells sense local metabolic conditions and signal nearby vascular smooth muscle cells to relax, leading to arteriolar vasodilation →Signals for vasodilation: NO, prostacyclin, endothelium-derived hyper polarizing factor →Signals for vasoconstriction: endothelin, vasoconstrictor prostaglandins *NO is very important in terminal arterioles and large arteries *Training enhances sectretion of vasodilation factors →At high exercise intensities, metabolic control is counterbalanced by sympathetic-mediated vasoconstriction (to protect blood pressure)

How are tissue needs for blood flow during exercise balanced with blood pressure homeostasis?

∙Tissue needs for blood flow (O₂ delivery) are balanced with blood pressure homeostasis by redistributing blood flow amongst the tissues ∙Tissue need for O₂→Local control: vasodilation→ ↑ local resistance & ↑ blood flow→ driving force for ↑TPR, ↑BP→ ↑ resistance, ↓ blood flow to other lesser priority tissues →Blood flow increases to skeletal muscle, heart (metabolic control autoregulation NO (endothelium) limited by compression), integument (↑ by all mechanisms of control; training ↑'s these values, esp w/ heat acclimation) →Stays the same to the brain (although more recent evidence says that flow increases quite a lot) →Decreases to kidney, gastrointestinal, others (ie. liver, spleen) (training increases these)

Give a general overview of the relative contributions of cellular ATPases to VO2 in the "standard state". (non exercising)

∙VO₂ is a proxy for energy expenditure ∙Total O₂ consumption in the standard state is ~90% mitochondrial and ~10% non-mitochondrial ∙Total mitochondrial O₂ consumption is ~80% coupled to ATP synthesis and ~20% uncoupled by proton leak ∙Total ATP consumption in the standard state is ~15% protein synthesis, ~15% Na⁺/K⁺ ATPase, ~10% Ca²⁺ ATPase, ~10% gluconeogenesis, ~10% urea genesis, ~10% actinomyosin ATPase, ~20% others (including RNA synthesis and substrate cycling)

Why is it feasible to estimate the contribution of aerobically generated energy to powering exercise by gas exchange measurements? What assumptions must be made to calculate the contribution of aerobic energy as the source for mechanical power output based on VO2?

∙VO₂ is directly proportional to metabolic rate ∙Under the conditions: all ATP is generated by oxidative phosphorylation, VO₂ is at steady-state, ATP & CP stores are maintained, lactate from anaerobic glycolysis is fully oxidized, protein catabolism & amino acid oxidation is negligible, such that RER=RQ →Assume constant efficiency, or that you have an accurate estimate of efficiency.

A supplement company claims that its product increases VO₂max and therefore should be used by athletes to improve their performance. Critically evaluate this statement.

∙VO₂max is just one component of performance, and there are tradeoffs ∙If you are interested in performance, measure performance (although typically if VO₂max improves, your performance will improve)

How does the myosin ATPase activity vary?

∙Varies according to the myosin heavy chain (MHC) isoform; higher ATPase activity= higher power ∙4 principle isoforms in adult mammalian skeletal muscle: type I, IIa, IIx (IId), IIb →each expressed in humans except IIb ∙Variability in S1 sub fragment (ATPase activity & cross bridge formation) →ATPase activities are different- rates are higher for shortening contractions compared to isometric

Besides epinephrine and norepinephrine, what are some additional hormones that control the heart and vasculature?

∙Vasopressin: →Hypothalamus > posterior pituitary gland →Potent vasoconstrictor →Inhibits cardiovascular drift (i.e. the tendency for ↑ heart rate and ↓ blood pressure during endurance exercise) ∙Renin-Angiotensin: →Kidneys: renin catalyzes hydrolysis of angiotensinogen →Ang II= vasoconstrictor of arteries & veins; raises BP via TPR →Promote aldosterone secretion: increases blood volume via kidney retention of fluid and salt ∙Vasopressin & renin-angiotensin are proportional to exercise intensity (there is a lower release in trained people)

How does exercise effect Ve, tidal volume, and frequency?

∙Ve (ventilation; L/min) increases as a function of intensity (up to ~20 fold) →There is a higher total ventilation compared to trained VO₂ continues beyond in absolute sense in the untrained person →Higher ventilation for a trained individual than untrained ∙Frequency and tidal volume increase during exercise because: Ve=f∙Vt

What is wet bulb globe temperature and why is it important?

∙WBGT index: represents the combined effect of air temperature, humidity, wind, thermal radiation (ex. sunlight) →WGT provides simpler approach because it is portable ∙Measures thermal stress

Is it plausible for someone to run a sub 2 hour marathon? Explain.

∙When the highest values of running efficiency are used with the highest values of VO₂ at LT, it is possible to run 1:57 →BUT, the combination of high VO₂max and economy is rare; may be a tradeoff (never been done before)

Is it possible for a muscle fiber to express more than one myosin heavy chain?

∙Yes! →Fibres and muscles tend to express specific isoform(s) predominantly according to their function, but have many distributed properties

Would you expect motor-unit rotation to operate during maximal-effort repeated contractions? Why or why not?

∙Yes, this would limit fatigue

Why is it difficult to interpret EMG? What are some of the pitfalls with this method?

∙iEMG ↑ during sustained isometric contractions is due to slowing muscle fibre conduction velocities and not progressive ↑ in recruitment! (b/c ↑'d MU recruitment is due to fatiguing was the original though, but it is much more complicated than that) ∙Resistance training dogma: optimal loading for hypertrophy (reps: 10-12, load: 80% 1-RM, high volumes, relatively short rest intervals) →In high load and low volume, you are recruiting more muscle fibres so it should be better for training...BUT at low load until failure, you have to recruit more fibres as the others fatigue →Low-load, high-reps (30% 1-RM) sets to volitional fatigue confer similar hypertrophic gains as high-load, low-rep sets →Low-load conditions can lead to progressive recruitment of fibres as others fatigue, which may be obscured if motor units are substituted or rotated