LEC10,11,12: LC and Ventilation

Question 1

What is the definition of physiological reserve?

Answer 1

Difference between baseline VO2 and ventilatory threshold

Question 1

When comparing a 45 kg pack to an unloaded pack, the reserve for prolonged word in the loaded pack in reduced by about (blank)?

Answer 1

16 percent

Question 2

Summary of the ventilatory response to exercise under load

Answer 2

1. An increase in load on thorax
2. Increase in the work of breathing (WOB)
3. Increase in respiratory muscle work/fatigue
   a. Increase in breathing discomfort
   b. Decrease in maximal inspiratory pressure (MIP)
4. Decrease in tidal volume (VT) and end inspiratory lung volume (EILV), increase in blood flow
5. Increase in dead space ventilation (VD)
6. Increase in ventilation

An increase in minute ventilation will cause an increase in the work of breathing

Question 3

How can we measure “physiological strain”?

Answer 3

Energy expenditure, heart rate, ventilation, perceived exertion

Question 4

How can we measure “work performance”?

Answer 4

Work tolerance, time to exhaustion, speed of movement

Question 5

What is work with load carriage compared to unloaded like?

Answer 5

Same task, same physiological strain, longer time

Same task, same time, greater physiological strain

Question 6

What can performance be measured by?

Answer 6

1. Power output
2. Exercise time (task completion time)
3. Time or repetitions to task failure
4. Work tolerance (time to exhaustion)
5. Task completion accuracy
6. Acceleration/speed
7. Mobility

Question 7

Why is physiological strain higher with load carriage?

Answer 7

1. More weight to support and move
   a. Higher energy requirements (eg. VO2)
   b. Greater cardiovascular and respiratory strain
   c. Altered biomechanics
   d. Altered metabolic efficiency
2. Secondary problems:
   a. Resistance to movement from added layers
   b. Altered breathing from restrictive armour or breathing apparatus
   c. Thermal strain from protective clothing
   d. Fluid balance
   e. Fatigue

Question 8

Performance decreased about (blank) per additional kg above base configuration

Answer 8

0.8%

Question 9

Ventilation equals what?

Answer 9

Tidal volume x Breathing frequency

Question 10

Lungs generally don’t limit exercise capacity in health BUT…

Answer 10

load carriage alters breathing pattern for the worst, may reduce job performance

Question 11

What is VE?

Answer 11

Ventilation (VE)
Rate of air expired

Breathing frequency (fB) x Tidal volume (VT)

VE = Alveolar ventilation (VA) + Dead space (VD)

Question 12

How to calculate operating lung volume?

Answer 12

EELV = TLC – IC

EILV = EELV + VT

Question 13

How do we express the operating lung volume?

Answer 13

EELV (%TLC) = EELV/TLC*100

EILV (%TLC) = EILV/TLC*100

Question 14

Characteristics differences between men and women in police and fire recruits

Answer 14

Height: men were taller (p=8%; f=6%)

Mass: men were heavier (p=22%; f=19%)

VO2peak: men were fitter (p=12%; f=5%)

Question 15

In general, what is the difference between females and males?

Answer 15

1. Females have smaller airways, lungs, and heart, and have slightly different ribcage anatomy.
2. Females also have a higher resistive component in the “work of breathing” -> greater Wb and VO2RM -> also greater dyspnea for a given VE
3. Expiratory flow limitation more prevalent in high-fit females than males
4. Females have been shown previously to adopt a more rapid and shallow breathing pattern compared to males in an occupational model

Question 16

At an absolute workload, females have greater (blank) than males

Answer 16

Greater VE, VE/VO2, and perceptual responses

Question 17

At relative workload, females would (blank) compared to males

Answer 17

perceive the same, but would be working at a lower absolute VO2 and VE

Question 18

Relative to total mass, at equivalent metabolic cost, VE/VO2 and perception is higher in (blank)

Answer 18

females