Fick equation

Question 1

What is the Fick Equation for VO₂?

Answer 1

VO₂ = Q x a-v O₂ diff
● VO₂ = oxygen consumption
● Q = Cardiac Output
● a-v O₂ diff = Arterio-Venous O₂ difference

Question 2

What is VO_2max?

Answer 2

The highest rate that oxygen can be taken into the body, transported, and utilized to perform work. Also called Aerobic Power

Question 3

What are the two ways VO_2max can be expressed?

Answer 3

● Absolute = L/min or ml/min
● Relative = mL/kg/min

Question 4

What does a high absolute VO_2max indicate?

Answer 4

A large “engine” or high capacity for oxygen consumption

Question 5

What does a high relative VO_2max indicate?

Answer 5

How well someone can move their own body mass

Question 6

What are the criteria for determining if VO_2max has been achieved during testing?

Answer 6

• Achievement of >90% of age-predicted maximum HR.
  ● RER > 1.1
  ● Blood [lactate] > 10 mmol
  ● Note: Volitional fatigue is not evidence that VO_2max was achieved

Question 7

What is the difference between “maximal” and “maximum” VO₂?

Answer 7

Maximum VO₂ refers to the absolute highest rate of oxygen consumption an individual can achieve. If, during a VO_2max test, the individual does not exhibit certain physiological indicators that confirm a true maximum was reached, the achieved value should be referred to as maximal VO₂ or VO2peak

Question 8

What are the characteristics of VO_2max/peak?

Answer 8

● Higher in men than women due to larger heart, increased blood volume, and increased muscle mass.
● Varies by exercise mode: Highest on Treadmill > Bike > Rowing > Swimming > Arm Crank
● Decreases ~10% per decade after ~age 30 due to decreases in max heart rate, SV, oxidative capacity & general deconditioning.
● Influenced by heredity and training (50-80% genetics, ~20-50% training).
● Affected by environment: altitude, pollution, diet (glycogen depletion, dehydration) can decrease VO_2max

Question 9

Does VO_2max respond to training?

Answer 9

Yes, but not every increase is attributed to training. Genetic predisposition plays a role

Question 10

How does cardiac output change with training?

Answer 10

Cardiac output increases with training, primarily attributed to improvements in stroke volume (SV)

Question 11

What are the two ways heart size can increase with training (cardiac hypertrophy)?

Answer 11

● Greater wall thickness (interseptum, ventricular wall)
● Larger internal cavity size (end-diastolic volume) - can hold more blood and take advantage of the Frank-Starling mechanism

Question 12

How does heart rate change with training?

Answer 12

Resting HR decreases. Max HR either goes up slightly or down slightly

Question 13

What hematological adaptations occur with training?

Answer 13

● Plasma volume increases due to increased ADH, aldosterone, and plasma proteins, causing more fluid retention in the blood.
● Red blood cell volume increases, but hematocrit decreases because plasma volume increases more.
● Blood viscosity decreases, improving circulation and enhancing oxygen delivery.
● Changes in plasma volume are highly correlated with changes in SV and VO_2max

Question 14

How does training affect vasodilation?

Answer 14

Training improves vasodilation, which increases blood flow to muscles

Question 15

What are the adaptations in muscle that occur with training?

Answer 15

● Capillarization: increased number of capillaries around each muscle fiber
● Decreased diffusion distance from capillaries to intermyofibrillar (IMF) mitochondria
● Increased myoglobin concentration
● Increased oxidative capacity of muscle
●All contribute to an increased a-v O2 diff

Question 16

What cardiovascular changes are observed at rest after training?

Answer 16

● Cardiac hypertrophy (increased cavity size of ventricle via “volume overload” and possibly increased wall thickness via “pressure overload”)
● Decreased resting HR
● Increased SV
● Increased total blood volume (~0.5 to 1.0 liters) and [Hb]
●Increased capillary density & oxidative capacity of muscle
● Decreased systolic BP (maybe)

Question 17

What cardiovascular changes occur during submaximal exercise after training?

Answer 17

● Increased SV at any given PO
● Decreased HR
● Cardiac output slightly decreased or no change
● Increased a-v O₂ diff
● BP_sys also lower (maybe)
● No change or slight decrease in muscle blood flow per kg of active muscle because of increased O2 extraction per unit of blood flow, increased mechanical and metabolic efficiency, and improvements in thermoregulation that can reduce blood flow demands.

Question 18

What cardiovascular changes occur during maximal exercise after training?

Answer 18

● Increased Q_max, primarily due to an increased SV_max
● Increased max muscle blood flow due to increased Q & blood volume and increased vasodilation (decreased TPR)
● Increased a-v O₂ difference (greater O₂ extraction)
● Max BP_sys stays the same or increases
● HR_max stays the same or slightly decreases < 5 b/min
● Result: Increase in VO_2max</sub

Question 19

What is the primary limiter of VO_2max in sedentary individuals?

Answer 19

Stroke volume

Question 20

Do elite aerobic endurance athletes need a high cardiac output and VO_2max?

Answer 20

Yes, they need a high cardiac output and VO_2max, especially a high VO₂ at the anaerobic threshold

Question 21

What can blood doping do?

Answer 21

● Increases hematocrit (~60%), hemoglobin content (~19 g/100 ml), and blood volume, resulting in increased O₂ carrying capacity and delivery of blood (increased cardiac output).
● Increases VO_2max between 4-13% and improves endurance performance times by 3-34%.

Question 22

What is Erythropoietin (EPO)?

Answer 22

● A hormone produced endogenously by the kidneys that causes increased RBC production in the spleen and marrow of the long bones
● Administration of commercially produced EPO can result in a higher total amount of RBCs and therefore higher [Hb] (~12% increase in [Hb] in ~6 weeks has been reported & lasts ~several weeks)

Question 23

What are the complications of blood doping?

Answer 23

● Hematocrits >60% can increase the likelihood of stroke, heart attack, pulmonary edema and death.
● Liver dysfunction has been reported if iron supplements are combined with EPO.
● There have been several athlete deaths, especially in Europe, as a direct result of blood doping in endurance athletes due to heart attack or stroke

Question 24

Can the respiratory system limit VO_2max?

Answer 24

Not under normal conditions. However, the PO₂ of arterial blood leaving the lung has been shown to decrease during maximal exercise in some individuals, decreasing the % of Hb saturated with O₂ leaving the lungs. This is termed arterial hypoxemia (EIAH) and is more prominent in highly active women

Question 25

What is arterial hypoxemia (EIAH)?

Answer 25

● A decrease in O₂ saturation of 4% from rest or a decrease to <90% in the blood leaving the lung.
● Results in less O₂ delivered to working muscle

Question 26

What are the possible causes of arterial hypoxemia during exercise?

Answer 26

● Capillary transit time may be too quick for full blood oxygenation due to high cardiac output and blood flow through the pulmonary capillaries (a type of “ventilation-perfusion mismatch”).
● There may be anatomical blood vessel (intrapulmonary) shunts (anastomosis) that bypass alveolar capillaries and result in deoxygenated blood being returned to the heart/body.
● Alveolar bleeding, edema and tissue damage can interfere with diffusion (diffusion limitation), decreasing SaO₂.
● Expiratory flow limitation (EFL): a mechanical limitation to increasing ventilation that prolongs expiratory time and increases work of breathing
● Exercise-induced bronchospasm (EIB) or asthma (EIA): a narrowing of bronchi due to smooth muscle contraction that can be induced by exercise, heavy breathing, and cold, dry and/or polluted air. Defined by some as a 10% lower FEV_1.0 after short-term, intense exercise (~6-8 minutes at up to 90% of HR_max) compared to rest. EIB/EIA is more prevalent in winter compared to summer Olympic sports. Note: does not necessarily mean you have asthma

Question 27

What is exercise-induced pulmonary hemorrhage (EIPH)?

Answer 27

Occurs when the high blood pressure in the pulmonary capillaries due to the high cardiac output results in such a high blood flow that pulmonary capillaries can rupture, producing bleeding in the alveoli that can be exhaled. This has been observed in thoroughbred racehorses. Some elite endurance athletes have also reported “tasting blood” or having an “iron taste” after intense exercise, which could be due to a similar phenomenon