Pulnomary responses to acute exercise in the trained state Flashcards Preview

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Flashcards in Pulnomary responses to acute exercise in the trained state Deck (20):

What does endurance training increase?

- Lactate threshold - less reliance on anaerobic glycolysis
- Stroke volume
- Heart rate reserve - lower resting heart rate
- Maximum cardiac output
- Active muscle oxygen extraction - ability of mitochondria
- Ventilatory demands
- FFA oxidation at low work rates


Define VO2 max?

- The maximum amount of oxygen that can be transported and utilised by the body
- Increase in workrate without an increase in VO2


What is the difference with a VO2 peak and VO2 max?

- VO2 peak is just the highest rate of VO2 attained on a particular test
- VO2 max is where where VO2 actually plateaus with an increasing work rate


What is the secondary ACSM criteria for VO2 max?

- RER above 1.15
- HR max in 10 beats of predicted
- Substantially high blood lactate
- Substantially high RPE


How is exercise intensity defined?

- A common set of physiological stressors consistent, among subjects, with the sensation or feelings of exertion


When does the lactate threshold occur and what does it depend on?

- Occurs at 45-85% VO2 max, depends on age, state of health and/or training
- Occurs at 50% VO2 max on average


What is lactate threshold commonly used for?

- Assess subjects integrative systemic function (fitness)
- Optimise training work rates
- Assess endurance progress
- Assess if people need surgery
- Indicate life expectancy
- Sort patients needs - ward or intensive care


Define the 4 exercise intensity domains

Moderate - No sustained increase in arterial blood lactate >3 hours (days)
Heavy - Sustained increase in arterial blood lactate - reaches steady state in 15-20 mins 1-3 hours
Very heavy - Progressive increase in arterial blood lactate throughout exercise 2-60 minutes
Severe intensity - Rapid muscle fatigue less than 2 minutes - above VO2 max


What is O2 conductance and how might it be effected in the trained state by the different systems?

- Ease with which O2 flow from atmosphere to mitochondrion
- Improvements with exercise only occur downstream of the lungs as lung structure doesn't change
- When trained lung can pose limitation if conductance of heart, circulation and muscle exceed the pulmonary system


Why is resting ventilation lower following exercise training? And alveolar ventilation?

- Reduction in RER as utilise more fatty acids
- PaCO2 stays relatively the same however VCO2 has reduced
(VA = 863 x VCO2/PaCO2)
- Less ventilator demand from deceased CO2 production


What is the benefit to having lower resting ventilation levels for LT and VO2 max?

- Increases the requirement for VE at VO2 max because higher metabolic rates (aerobic and anaerobic) can be achieved
- Increases lactate threshold by increasing aerobic capacity of skeletal muscles


What happens at higher VE sustained with elite athletes?

- Greater VE, greater the likelihood of expiratory flow limitation


What is exercise induced atrial hypoxemia (EIAH) and when is it most prevalent

- Lower than normal oxygen saturation in the arterial blood consequent to acute exercise
- Seen in trained subjects with high VO2 max


What causes exercise induced arterial hypoxia

1) PO2 of inspired air - altitude?
2) Hypoventilation - Not enough O2 getting to the alveoli
3) Diffusion - Limitation to O2 diffusing from alveoli to RBC's
4) Systemic arterial blood diluted by blood from systemic venous system
5) Ventilation-perfusion mismatch - Blood flow in the lung isn't matched to distribution of ventilation


What are the different definitions of EIAH Sa02%

Mild: 93-95%
Moderate: 88-92%
Severe: <88%


What else is a feature of EIAH?

- Poor respiratory compensation for metabolic acidosis of high intensity exercise
- Suggests reduced ventilatory drive or limitations to alveolar ventilation


What is the mean capillary transit time and what happens to it with exercise? How it is compensated for?

-Mean capillary transit time = Capillary volume/ Capillary flow
- Decreases with exercise as maximum cardiac output increases - 02 doesn't have time to diffuse
- Larger recruitment of capillaries


What happens with intrapulmonary arteriovenious shunt when exercise trained?

- Shunt pathways recruited to decrease intrapulmonary pressure
- Right ventricle to left - blood doesn't get pumped to lung to be reoxygenated


How is the ventilation perfusion mismatch effects with EIAH

- Increase in VA/Q ratio
- Increased pulnomary vascular pressure reduces the gravitational-dependent difference in pulmonary blood flow but increases capillary filtration
- Causes interstitial oedema during exercise
- Ventilation distribution isn't effected


What is the alveolar-capillary stress failure? What happense with exercise?

-In trained: High VT and Fr increase mechanical strain on the lung
- High max cardiac output without an increase pulmonary cross sectional area increases pulmonary blood flow, filtration and vascular pressure
- Capillary stress failure seen as transpulmonary pressure 40-60mmHg