LEC10,11,12: LC and Ventilation Flashcards
What is the definition of physiological reserve?
Difference between baseline VO2 and ventilatory threshold
When comparing a 45 kg pack to an unloaded pack, the reserve for prolonged word in the loaded pack in reduced by about (blank)?
16 percent
Summary of the ventilatory response to exercise under load
- An increase in load on thorax
- Increase in the work of breathing (WOB)
- Increase in respiratory muscle work/fatigue
a. Increase in breathing discomfort
b. Decrease in maximal inspiratory pressure (MIP) - Decrease in tidal volume (VT) and end inspiratory lung volume (EILV), increase in blood flow
- Increase in dead space ventilation (VD)
- Increase in ventilation
An increase in minute ventilation will cause an increase in the work of breathing
How can we measure “physiological strain”?
Energy expenditure, heart rate, ventilation, perceived exertion
How can we measure “work performance”?
Work tolerance, time to exhaustion, speed of movement
What is work with load carriage compared to unloaded like?
Same task, same physiological strain, longer time
Same task, same time, greater physiological strain
What can performance be measured by?
- Power output
- Exercise time (task completion time)
- Time or repetitions to task failure
- Work tolerance (time to exhaustion)
- Task completion accuracy
- Acceleration/speed
- Mobility
Why is physiological strain higher with load carriage?
- 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 - 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
Performance decreased about (blank) per additional kg above base configuration
0.8%
Ventilation equals what?
Tidal volume x Breathing frequency
Lungs generally don’t limit exercise capacity in health BUT…
load carriage alters breathing pattern for the worst, may reduce job performance
What is VE?
Ventilation (VE)
Rate of air expired
Breathing frequency (fB) x Tidal volume (VT)
VE = Alveolar ventilation (VA) + Dead space (VD)
How to calculate operating lung volume?
EELV = TLC – IC
EILV = EELV + VT
How do we express the operating lung volume?
EELV (%TLC) = EELV/TLC*100
EILV (%TLC) = EILV/TLC*100
Characteristics differences between men and women in police and fire recruits
Height: men were taller (p=8%; f=6%)
Mass: men were heavier (p=22%; f=19%)
VO2peak: men were fitter (p=12%; f=5%)
In general, what is the difference between females and males?
- Females have smaller airways, lungs, and heart, and have slightly different ribcage anatomy.
- Females also have a higher resistive component in the “work of breathing” -> greater Wb and VO2RM -> also greater dyspnea for a given VE
- Expiratory flow limitation more prevalent in high-fit females than males
- Females have been shown previously to adopt a more rapid and shallow breathing pattern compared to males in an occupational model
At an absolute workload, females have greater (blank) than males
Greater VE, VE/VO2, and perceptual responses
At relative workload, females would (blank) compared to males
perceive the same, but would be working at a lower absolute VO2 and VE
Relative to total mass, at equivalent metabolic cost, VE/VO2 and perception is higher in (blank)
females
