Exercise physiology 2 Flashcards
The heart is regulated by…
by the heart itself (pacemaker cells) and the CNS
Max heart rate is not affected by endurance training
true/false
true
Max heart rate declines with…
Max heart rate declines with ageing
(altered sensitivity for sympathetic stimulation)
What three factors determine stoke volume?
- Venous return (more blood returning = increase stroke volume)
- Sympathetic nervous system
- Arterial pressure counteracts the effect (higher during exercise)
During exercise, net stroke volume increases
Cardiac output is ? and it is increased during exercise
heart rate *stroke volume (l/min)
In endurance trained athletes, the resting parasympathetic activity A, sympathetic activity B, heart rate C.
Diastolic volume D, systolic volume E, stroke volume F
A increases
B decreases
C decreases
D increases
E decreases
F increases
Sedentary vs athletes: difference in resting heart rate, resting stroke volume, resting cardiac output (l/min)?
- heart rate increase sedentary
- resting stroke volume decrease sedentary
- resting cardiac output the same
Maximal heart rate does/does not increase by training
does not
Cardiac output in athletes: is it increased during exercise vs students? Why/why not?
Yes, it is caused by the increased stroke volume
Cardiovascular drift: this happens during exercise >15 min. What happens with stroke volume, heart rate, CBF (cutaneous blood flow), venous return?
Stroke volume down
Heart rate up
CBF (blood flow to skin) up
venous return down
An untrained and trained subject perform aerobic exercise at exactly the same level. Who has the highest O2 consumption and cardiac output?
No large differences.
Same level exercise: you need roughly the same amount of energy, same cardiac output, same O2 consumption. However, the athlete has a lower heart rate.
An untrained and trained subject perform aerobic exercise at their maximum level. Who has the highest O2 consumption and cardiac output?
Trained athlete.
Now the situation is not comparable. Trained subject has higher performance. More energy needed.
cardiac functioning important determinant of aerobic performance: yes or no
yes. VO2 max related to max cardiac output
Cardiac output increases to a lesser extent than O2 consumption. How is this extra O2 delivered? What may explain the disrepancy between cardiac output (max increase 8x) and O2 consumption (max increase 23x)?
Increased O2 extraction by exercising tissues + selective blood flow to exercising tissues
VO2 max increases by training: cardiac output and O2 extraction. What is the small effect and what is the main effect?
Small effect of training on extraction of oxygen, main effect on cardiac output.
Static exercise, heavy load:
- increase in X blood pressure (stroke volume)
- increase in X blood pressure
Muscle contraction >60% of max force occludes muscle blood flow and results in high vascular resistance
Systolic,
diastolic
Dynamix exercise, increasing intensity:
Increase in X blood pressure (stroke volume)
Little effect/small decrease in X blood pressure
Why?
Systolic
Diastolic
Alternating contractions and relaxations facilitate muscle blood flow -> lower vascular resistance
Consider the effects of vascular resistance on blood pressure. Is there a difference in blood pressure responses between arm and leg exercises (at similar level of effort: same % VO2 max)
Yes, higher increase in arm exercise:
Smaller muscle mass and vasculature in arms results in greater resistance to blood flow. Blood that flows through the arm to deliver the same amount of oxygen experiences much more resistance: same amount of blood is required for this VO2 max.
Regulation of blood flow: Blood flow is devided amongst different organs during rest. During exercise, much more blood goes to the muscles. What is important to keep in mind?
This is relative, because there is much more blood to devide
How does the dilation and vasoconstriction work in the arteries? How is this determined?
Metabolism up
O2 down
CO2 up
vasodilation
resistance down
blood flow up
Vice versa with constriction
What are extrinsic factors for vasodilation/constriction?
- sympathetic nervous system: vasoconstriction
- epinephrine: constriction or dilation (dilation to heart and muscle)
- NO parasympathetic innervation of vascular smooth muscle cells
- NO: vasodilation
Where does NO come from?
synthesized from arginine
- Vascular endothelium contains endothelial NO synthase
The more nitrite, the more flow-mediated dilation, more maximal power
- Several studies show positive effects of NO donors on performance
- Other studies show no effect (especially in well-trained subjects)
Ok
Summary: to meet the increased demand of oxygen during aerobic exercise, these processes are all upregulated:
Pulmonary ventilation up
Cardiac output up (heart rate and stroke volume up)
Unloading oxygen from haemoglobin up
Training increases aerobic performance:
What are the effects on the following factors?
- pulmonary ventilation
- cardiac output
- stroke volume
- blood flow to skeletal muscles
- capillarization
- unloading of oxygen from haemoglobin
- oxidative capacity of muscle fibers
(mito biogenesis, mito enzyme activity) - exercise-induced restriction of blood flow to splanchnic organs
- no effect
- increase
- increase
- increase
- increase
- small effect
- increase (increase, increase)
- decrease
Now, recall on what things training on aerobic performance has an effect
BUCC
POES
- blood flow to skeletal muscles
- unloading of oxygen from haemoglobin
- capillarization
- cardiac output
- pulmonary ventilation
- oxidative capacity of muscle fibers
(mito biogenesis, mito enzyme activity) - exercise-induced restriction of blood flow to splanchnic organs
- stroke volume