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%
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