Week 6 Key Reading - A. William Sheel Flashcards
What is the process of inspiration ?
When the inspiratory muscles contract there is an expansion of the chest cavity (increased volume) and pleural pressure becomes sub-atmospheric.
The pressure change causes alveolar pressure to also become sub-atmospheric, which induces airflow into the lung from the atmosphere. The primary muscle of inspiration is the diaphragm.
What is the process of expiration?
During quiet breathing at rest, expiration is achieved passively via elastic recoil of the lung and chest wall.
During exercise the muscles of expiration are recruited to forcefully exhale air and return lung volume to normal resting values. The most important muscles of expiration are the abdominal muscles - rectus abdominis, internal and external obliques, and transversus abdominis.
State the metabolic, cellular and structural changes in limb locomotor muscles associated with whole-body endurance training.
Metabolic
- Glycotic enzymes increases
- Aerobic enzymes increases
- Max lactate level increases
- AVO2 diff increases
Cellular
- Glycogen increases
- Mitochondria increase
- Mitochondria volume increases
- ATP increases
- PCr increases
- Cr increases
Structural
- Type I fibre increases
- Type II fibre decreases
- Capillarisation increases
What are the theorised mechanisms to explain reported improvements in exercise performance from RM training?
- Improved ratings of breathing perception
- Delay of RM fatigue
- Ventilator efficiency
- Blood-flow competition between respiratory and loco motor muscles.
What are typical values for VE at rest and during exercise for average vs elites ?
Rest 6-8 Litres/min
Exercises
Average - 120-130 L/min
Elite - 200+ Lmin
During exercise which respiratory muscle is required primarily ?
The diaphragm is recruited significantly more during exercise than during rest and that it, in turn, must receive a higher proportion of cardiac output during exercise.
With increased cardiac output what can be an issue for gaseous exchange between respiratory components ?
A greater level of O2 is required however because the Q is higher there is less time for O2 to diffuse from the alveoli into the arterial blood and then less time for this O2 to be extracted into the Muscle cells.
Increased capillary density can help this but it only accounts for a small change in AVO2 difference.
What are some adaptations to respiratory muscle training ?
Specific RM training has been reported to result in:
Significant improvements in:
- Peak inspiratory pressures
- Sustained ventilatory capacity tasks
- Exercise performance
How do breathing patterns change during exercise?
The pattern of RM contractions during exercise produces changes in tidal volume (VT), end-inspiratory and end-expiatory lung volumes, inspiratory and expiatory flow rates and respiratory timing.
The increase in V̇E during exercise is caused by increases in both VT and breathing frequency (ƒb). In normal young individuals engaged in low-intensity exercise, both increases in VT and ƒb contribute to the rise in V̇ E.
VT Platues at 50-60% vital capacity. So how is minute ventilation (VE) improved at higher intensities?
By increasing in breathing rate.
The Diaphragm is a highly capillarised near perfect structure, however, when can it fail ?
Up to 80% VO2max the diaphragm is able to perform its job properly, however, sustained exercise above this point can lead to fatigue of these muscles.
