5. Cardiorespiratory Adaptations to Endurance Training Flashcards
Cardiovascular Adaptations
Increased oxygen delivery
Increased oxygen extraction
Increased oxygen delivery causes increased
– Blood volume
– Cardiac output (= HR SV)
– Coronary blood flow
– Muscle blood flow
Increased oxygen extraction
– Arterio-venous oxygen difference
what is Cardiovascular Adaptations
Adaptations which enhance oxygen
delivery
why is blood volume post-training increased
Initially mainly due to increased plasma volume
Increased Red Blood Cell Volume post-training
Initially red blood cell volume remains
unchanged then small increase
– ->erythropoietin (EPO) from liver and kidney
what does erythropoietin (EPO) do
Acts to increase red blood cell production in the bone marrow
Reduced Haematocrit is caused by
Plasma and red blood cell volume increase
Plasma volume increases > red blood cell volume
Reduced Haematocrit effect on 02 delivery
Blood is less viscous
* Decreased resistance to flow
* Enhanced 02 delivery
Increased Haemoglobin post-training
Increases in plasma volume and red cell volume become more even
* Haematocrit returns to normal
* Oxygen carrying capacity of blood remains enhanced due to increased haemoglobin
Increased Stroke Volume PT
Increased at rest and during
submaximal exercise
* Maximal stroke volume increased
Mechanisms of Increased Stroke
Volume
Greater ventricular filling due to
->Increased end-diastolic volume
Greater ventricular filling due to :
– Increased blood volume
– Increased ventricular chamber size
– Greater diastolic filling time (due to reduced heart rate)
→ Increased end-diastolic volume
– Greater stretch of ventricular wall (preload)
– Increased force of contraction (Frank-Starling mechanism)
– Greater ventricular output (increased stroke volume)
Repetitive volume overload =
Increased chamber size:
* LV dilation
Increased wall thickness:
* Pressure overload
* Normalize wall stress
HR PT
Reduced resting hr
Reduced hr at any submaximal work rate
Max hr unchanged
Cardiac Output PT
CO = HR SV
No change in CO at rest or at
submaximal exercise
Can increase substantially at max intensity
Athlete’s artery
larger lumen dimension
<– wall thickness
Increased Muscle Blood Flow PT
Muscle blood flow –> in exercise
(next session)
Greater –> in trained individuals
Mechanisms of Increased Muscle
Blood Flow
–> capillary density (next session)
Greater capacity for vasodilation
–> sympathetic input
to smooth muscle in arteriole walls
Improved Coronary Blood Flow PT
–> Internal diameter of coronary arteries (2-3x marathon)
Greater capacity for vasodilation in coronary arteries (2x marathon) (more important)
Respiratory Adaptations PT
No change in lung capacity (no structural changes)
* Tidal volume
– Unchanged at submax work rates
– Max tidal volume increased
* Respiratory rate
– Slightly reduced at rest
– –>Max respiratory rate
* –>Max ventilation substantially (240 l·min-1)
Increased Maximum Oxygen Uptake PT (R)
VO2 max –> 5-30 %
* Dependent on initial value
* Dependent on frequency, intensity, duration of exercise
* Genetic endowment
sets upper limit
Increase in VO2 max post-training
50 % due to –> CO
50 –> arterio- venousO2 difference
