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Exercise Phys > Limitations to Exercise > Flashcards

Limitations to Exercise Flashcards

1
Q

What is the formula for respiratory quotient (RQ)?

A

RQ = VCO2/VO2 (typically between 0.7-1.0)

RQ = Volume of oxygen consumed / volume of oxygen produced

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2
Q

What does the RQ ratio describe?

A

The Respiratory quotient (RQ) describes the ratio of CO2 produced and O2 consumed for complete oxidation of either carbohydrate, fat, or protein but it seldom reflects oxidation of one macronutrient, but instead a mixture with an RQ intermediate between 0.70 and 1.00

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3
Q

What is the RQ value for carbohydrates?

A

1.00

Complete oxidation of one glucose molecule requires six O2 molecules and produces six CO2 and six H2O molecules

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4
Q

What is the RQ value for fat?

A

0.70

Fat catabolism requires more O2 consumed in relation to CO2 produced because fat contains more hydrogen and carbon atoms than oxygen atoms

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5
Q

What is the RQ value for protein?

A

0.82

Proteins oxidize to CO2 and H20; but N2 of the amino acid must first be removed & remaining keto acid fragment requires more O2 in relation to CO2 produced

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6
Q

What do we assume about the rate of O2/CO2 usage?

A

rate of o2/co2 exchange in the lungs = the rate of o2/co2 usage and release in the tissues

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7
Q

What are 3 things that are exempt from these assumptions?

A
  1. Hyperventilation – over-breathing i.e. excess CO2 produced
  2. Exhaustive activity – increase in CO2 produced due to the presence of H2CO3 resulting from lactate buffering
  3. Gluconeogenesis - formation of glucose within the animal body from precursors other than carbohydrates especially by the liver and kidney using amino acids from proteins, glycerol from fats, or lactate produced by muscle during anaerobic glycolysis
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8
Q

What is the difference between RQ and RER?

A

RER (respiratory exchange ratio)

It reflects the respiratory exchange ratio of CO2 and O2

RER CAN EXCEED 1!!

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9
Q

What occurs during strenuous exercise?

A

The volume of CO2 production rises as a result of hyperventiliation and the increased buffering of blood lactic acid derived from skeletal muscles thus the RER no longer reflects substrate usage but rather high ventilation rates and blood lactate levels

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10
Q

What is submaximal activity?

A
  • activity that is less then maximal
  • heart rate is 50 to 80% of maximum
  • aerobic capacity (VO2max) is not reached
  • E.g. walking, jogging, cycling, swimming
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11
Q

What is maximal activity?

A
  • aerobic capacity or VO2 max is reached

- E.g. heavy intense exercise

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12
Q

What increases with exercise intensity?

A

Metabolic rate

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13
Q

What is slow component of VO2 uptake kinetics?

A
  • At high power outputs, VO2 continues to increase above lactate threshold
  • More type II (less efficient) fiber recruitment
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14
Q

What is a VO2 drift?

A
  • Upward drift observed even at low power outputs

- Possibly due to an increase in ventilation & effects of increased circulating catecholamines, e.g. adrenaline

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15
Q

What is VO2 max?

A
  • Point at which O2 consumption no longer increases with an increase in exercise intensity
  • Best single measurement of aerobic fitness
  • Plateaus after 8 to 12 weeks of training
  • VO2 max is expressed in L/min
  • VO2 max normalised for body weight (ml O2 x kg-1 x min-1)
  • VO2 PEAK IS REACHED BEFORE VO2 MAX
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16
Q

What 2 things does training increase in athletes?

A

O2 delivery and O2 uptake

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17
Q

What are the 2 limits to VO2 max?

A
  1. Central physiological functions
    - - pulmonary diffusion
    - - cardiac output (CO = SV x heart rate)
    - - blood oxygen carrying capacity (volume and flow)
  2. Peripheral physiological functions
    - - muscle diffusion capacity
    - - mitochondrial enzyme levels
    - - capillary density
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18
Q

Which two peripheral physiological functions can be changed with training?

A
  • Mitochondrial enzyme levels

- Capillary density

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19
Q

How do we measure anaerobic contribution?

A
  1. Excess Post-exercise Oxygen Consumption
  2. Lactate threshold
  3. Economy of effort
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20
Q

What is excess post-exercise oxygen consumption?

A

Once exercise ceases, oxygen consumption does not immediately decrease to resting levels rather it decreases gradually

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21
Q

What 6 factors does EPOC rely on to work properly?

A
  1. Replenishment of oxygen stores
  2. Clearing CO2
  3. Elevated body temperature
  4. Elevated concentrations of noradrenaline and adrenaline
  5. Clearing lactate
  6. Replenishing ATP-PCr
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22
Q

Where is noradrenaline released from?

A

From the sympathetic nerve terminals

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23
Q

Where is adrenaline released from?

A

From the adrenal medulla and sympathetic branch of the autonomic nervous system

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24
Q

What are the 5 components of EPOC?

A
  1. Replenishment of energy sources – ATP-PCr; glycogen; lactate clearing
  2. Re-oxygenation of blood
  3. Decrease in circulatory hormones – adrenaline; noradrenaline
  4. Decrease in body temperature
  5. Decrease in ventilation & heart rate – to clear CO2 from body
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25
Q

What is lactate threshold?

A

Point at which blood lactate production exceeds the body’s ability to clear lactate. Individuals with higher lactate thresholds are capable of better endurance performances

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26
Q

Where is CO2 transported to from active muscles?

A

It is transported from active muscles to the lungs dissolved as carbonic acid which dissociates into H+ and bicarbonate ion which enters the blood stream and acts as a buffer

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27
Q

What is the partial pressure of CO2 in the plasma determined by?

A

By the lungs

If CO2 partial pressure increases then more is blown off by the lungs

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28
Q

How does the body prevent lactate accumulation in muscles?

A

To prevent lactate accumulation in muscles the body uses the cori cycle to send lactate back to liver for reconversion to pyruvate or gluconeogenesis

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29
Q

What 5 things does aerobic training require?

A
  1. Regular periods of stress and recovery
  2. An activity of intensity that must be higher than a critical threshold
  3. Period of activity must be of sufficient duration
  4. Repetition of the activity over time on a regular basis
  5. Sufficient rest must occur between each training session, because it is during the recovery period that the adaptations to exercise actually occur
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30
Q

What is enzyme adaptation during training?

A

Training causes a slow increase in the level of several enzymes, as well as in the number of capillaries, VO2max, and size of muscle fibers. These changes reverse rapidly on the cessation of training

31
Q

What 4 things does appropriate training for endurance result in?

A
  • Increases in VO2max
  • Increases in the maximal O2delivery by increasing plasma volume and maximal cardiac output
  • Enhancement of O2diffusion into muscle
  • Increases in the mitochondrial content of skeletal muscle fibres
32
Q

What are the characteristics of athletes in aerobic endurance events?

A
  • High VO2 max
  • High lactate threshold
  • High economy of effort
  • High % of type I muscle fibres
33
Q

What is fatigue?

A

If exercise is sustained for a prolonged time,
Eventually muscular contraction cannot be sustained and performance will diminish.
This inability to maintain muscle contractions is broadly called fatigue

34
Q

What are the 4 major causes of fatigue?

A
  1. Inadequate energy delivery/metabolism
  2. Accumulation of metabolic by-products
  3. Failure of muscle contractile mechanism
  4. Altered neural control of muscle contraction
35
Q

What is phosphocreatine depletion (PCr)?

A
  • PCr is used for short term, high intensity effort
  • Pacing helps defer PCr depletion
  • PCr has a key role in rapidly generating ATP during exercise
36
Q

What is glycogen depletion?

A
  • Depletes more quickly with high intensity & during first few minutes of exercise versus later stages
  • Decrease in glycogen stores in type I & IIa muscle fibres decrease power output – “hitting the wall”
  • Glycogen depletion occurs in different muscle fibres and groups at different rates
  • Also limits performance in activities that are over 60-90 minutes
37
Q

What does the accumulation of Pi lead to?

A

A decrease in;

  • contractile force
  • Ca2+ release from the sarcoplasmic reticulum
38
Q

What does heat do in fatigue?

A
  • Gets retained by body, core temp increases
  • Alters metabolic rate and enzymes
  • Time to fatigue alters with temp
39
Q

How does lactic acid affect fatigue?

A
  • H+ accumulation causes a decrease in muscle pH
  • Buffers minimize drop in pH
  • H+ may displace Ca2+ from fibre and disrupt action-myosin cross bridges
40
Q

What does depletion of glycogen granules do in fatigue?

A
  • Depletion of glycogen granules localized in myofibrils interferes with excitation-contraction coupling & Ca2+ release from sarcoplasmic reticulum
41
Q

What is neural transmission (PNS)?

A

Failure may occur at neuromuscular junction, preventing muscle activation

42
Q

What are the 4 possible causes of neural transmission in fatigue?

A
  • Decrease in ACh synthesis and release
  • Altered ACh breakdown in synapse
  • Increase in muscle fibre stimulus threshold
  • Altered muscle resting membrane potential
43
Q

What is the role of CNS in fatigue?

A
  • It plays a role but not fully understood yet
  • Brain regulates power output by the msucles to prevent unsafe levels of exertion that may damage tissue
  • Limits exercise by decreasing recruitment of muscle fibers which in turn causes fatigue
  • Perceived fatigue usually precedes physiological fatigue
  • Elite athletes learn proper pacing, tolerate fatigue
44
Q

What are the two types of muscle soreness?

A
  1. Acute soreness

2. Delayed-onset Muscle Soreness (DOMS)

45
Q

What is acute soreness?

A

Occurs during and or immediately following strenuous or novel exercise

It is an accumulation of metabolic by-products (H+)

Muscle begins to swell (Oedema)

Disappears within minutes to hours

46
Q

What are DOMS?

A

Occurs 24 to 48 hours AFTER exercise

Ranges from stiffness to severe restrictive pain

Major cause = eccentric contractions (eg. running downhill)

NOT CAUSED BY INCREASING BLOOD LACTATE CONCENTRATIONS

Damage precipitates hypertrophy

47
Q

What are the 2 theories to explain for DOMS?

A
  1. Structural explanation of DOMS
  • Structural damage indicated by muscle enzymes (e.g. creatine kinase) in blood
  • concentrations increases 2 to 10 times after heavy training
  • onset of DOMS parallels onset of increasing muscle enzymes
  • Z-disk myofilament damage after eccentric work
    this muscle damage precipitates hypertrophy
  1. Inflammation explanation of DOMS
  • Connection between inflammation and soreness - white blood cells defend body against foreign materials and pathogens, their concentration increasing with soreness
  • Substances released initiate inflammation, damaged muscle cells attract neutrophils which release attractant chemicals, radicals
  • Released substances stimulate pain nerves & macrophages (cell of immune system) remove cell debris.
48
Q

What are the sequence of events in DOMS?

A
  1. High tension in muscle leads to structural damage to muscle & its cell membrane
  2. Membrane damage disturbs Ca2+ homeostasis in injured fibre which inhibits cellular respiration
    [Ca2+] activates enzymes that degrade Z-disks
  3. After a few hours, circulating neutrophils increase
  4. Products of macrophage activity & intracellular contents (e.g. histamine, kinins, K+) accumulate outside cell
    Stimulates pain in free nerve endings
    Worse with eccentric exercise
  5. Fluid and electrolytes move into the area, creating oedema
49
Q

What are the three factors that loss of strength comes from?

A
  1. Physical disruption of muscle
  2. Failure in excitation-contraction coupling
  3. Loss of contractile protein
50
Q

What are 3 strategies to reduce DOMS?

A
  1. Minimize eccentric work early in training
  2. Start with low intensity and gradually increase
  3. Start with high-intensity, exhaustive training but soreness can be bad at first, much less later on
51
Q

What are the 2 types of muscle cramps?

A
  1. Exercise associated muscle cramps
  • Occur during or immediately after exercise
  • Fatigue caused ALTERED NEUROMUSCLAR CONTROL and results in the excitation of muscle spindle and inhibition of Golgi tendon organ
  • Relieved by stretching
  1. Heat cramps
    - Often associated with large sweat and electrolyte losses, especially sodium and chloride
    - Treatment is high-sodium solution, ice, and massage
52
Q

What happens when the pulmonary ventilation increases?

A

As the breathing rate increases, it caused CO2 in the alveoli to be reduced and CO2 blown off as it moves out of the blood and into the lungs

As a result, pH increases

53
Q

What is respiratory alkalosis?

A

The blood pH increases

Less carbonic acid

54
Q

What is pulmonary diffusion?

A

The amount of gas transferred from the alveoli to the capillary blood per unit time

55
Q

What is hypoxia?

A

A condition in which body is deprived of adequate oxygen supply

56
Q

What are the chain of events in hypoxia?

A
  1. Low PO2 at high altitude
  2. Sensed by carotid body which alerts brain.
  3. Brain sends signal to body to increase breathing rate
  4. Increase heart rate
  5. Dilate peripheral blood vessels in arms, legs, hands and feet
57
Q

What are the respiratory responses to altitude?

A
  • Pulmonary diffusion remains similar
  • Pulmonary ventiliation increasing causes decrease of CO2 in alveoli, CO2 moves from blood into lungs
  • Blood pH increases
  • Oxyhaemoglobin dissociation curve - LEFTWARD SHIFT
58
Q

What does 2,3-DPG normally ensure?

A

Ensures curve moves to right (TO NORMAL)

2,3-BPG binds to T state is stabilised and % curve shifts to the right

Hb gives up oxygen more readily in the tissues

59
Q

What are the cardiovascular responses to altitude?

A

Blood volume -decreases in plasma volume due to respiratory H2O loss and increase in urination

Haematocrit - increase due to respiratory H2O loss & an increase urination

Sympathetic nervous system – stimulates adrenaline and noradrenaline release – which leads to altered cardiac function (stimulated by ascent) which persists for several

cardiac output – different in submaximal vs maximal activity

60
Q

What is the formula for Cardiac output?

A

Cardiac Output = Heart Rate x Stroke Volume

61
Q

In submaximal activity, what happens once stroke volume decreases?

A

the decrease in stroke volume (due to decrease in plasma volume) leads to an increase in heart rate – peaks at 6-10 days – thereafter decreases as increases to HR not efficient to way to deliver O2 to tissues

62
Q

What happens in maximal activity?

A

There is a decrease in the maximal stroke volume (due to decrease in plasma volume) AND a decrease in the maximal heart rate (due to reduction in sympathetic nerve activation possibly due to reduced number of β receptors in heart)

63
Q

What is the VO2max response to altitude?

A

VO2max decreases with increasing altitude decreasing 10% for every 1000m ascent above 1500m

64
Q

What is the renal response to altitude?

A

Decrease in plasma volume due to increase in urination (diuresis)

Increase in erythropoietin (EPO) release from kidneys – this stimulates red blood cell production

excretion of HCO3- ions to offset respiratory alkalosis

65
Q

What are the metabolic responses to altitude?

A

increase in BMR – reliance on carbohydrate as it yields more energy per litre

Expect an increase in anaerobic metabolism at altitude due to hypoxic conditions (LESS O2!)

Expect to see an increase in lactic acid initially

Lactate paradox – high altitude natives generate lower-than-expected amounts of lactate – initial increase reversed as acclimate despite no change in VO2max – no explanation for this

66
Q

TRUE OR FALSE? Anaerobic performance unaffected at moderate altitude?

A

TRUE

67
Q

What is acclimatisation?

A

occurs within an individual organism

changes within a lifetime

results from an environmental change, reversible change

due to natural conditions
phenotypic change
ecological response

68
Q

What is acclimation?

A

occurs within an individual organism

changes within a lifetime

results from an environmental change, reversible change due to experimental conditions

can be in laboratory or controlled field setting
phenotypic change
ecological response

69
Q

What is adaptation?

A

occurs within a group of individuals (population)

changes over several generations

results from an environmental change, irreversible change due to either natural or experimental conditions
(artificial selection)

genetic change
evolutionary response

70
Q

What does acclimation do to altitude?

A

Acclimation does improve exercise performance but performance may never match that at sea level takes 3 weeks for moderate altitude (2210)

71
Q

What physiological adaptations do we see?

A
  1. Pulmonary adaptations
    - Increase in ventilation
    - Increase in pulmonary diffusing capacity
    - Appears to arise from an increase in the blood volume of pulmonary capillaries
  2. Blood adaptations
  • Increase in EPO initially
  • plasma volume returns to normal
  • Increase in 2,3-BPG causes a rightward shift to dissociation curve
  • Increase in tissue vascularity
  1. Muscle adaptations
  • Decrease in mass
  • Decrease in fibre
  • Decrease in glycolytic enzyme activities
  • Decrease in mitochondrial function
  1. Cardiovascular adaptations
  • No major adaptations
  • VO2max never improves much
72
Q

What is the best training regime to improve sea-level performance?

A
  • Live high (2500m) and train low (1250m)
73
Q

What are the 2 best training regimes to improve performance at altitude?

A
  1. Compete immediately following arrival – no acclimation benefits but no adverse affects of altitude
  2. Compete after two weeks training at high altitude - some acclimation but most adverse affects of
    altitude over
74
Q

What are the health risks of acute exposure to altitude?

A
  • Mountain sickness
  • High-altitude pulmonary oedema (HAPE)
  • High altitude cerebral oedema (HACE)
  • Hypothermia
  • Frostbite
  • Cardiorespiratory effects
  • Exercise-induced asthma

Exercise Phys (4 decks)

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