Exercise & Pulmonary-Circulatory Interactions

Question 1

How many Muscles are involved in Breathing?

Answer 1

• 63 muscles with a documented role in breathing
• 20% of the 320 pairs of human skeletal muscles

Question 2

What demands are placed on the respiratory system muscles during exercise?

Answer 2

• Mechanical work
• O2 uptake by respiratory muscles (9-15% VO2max)
• Diaphragm fatigues

Question 3

What happens when you reduce diaphragmatic work during exercise?

Answer 3

Prevents exercise-induced diaphragm fatigue

Decrease
- locomotor muscle fatigue
- sensation of dyspnea and limb discomfort
- sympathetic tone

increase
- exercise duration
- vascular conductance
- blood flow

Question 4

If you increase blood flow to the legs during exercise, where does the blood come from?

Answer 4

• Respiratory muscle blood flow

Question 5

What supports the notion of a ‘competitive’ relationship between active vascular beds during exercise?

Answer 5

• Directionally opposite changes in blood flow between respiratory and locomotor muscles

Question 6

What leads to increase group III-IV afferent activity? What does it lead to?

Answer 6

Cause
- High-intensity contractions
Leads to
- sympathetically mediated vasoconstriction of respiratory and locomotor muscle vasculature