Week 11 - Critical Power, W' & W'bal Flashcards
At an intensities below LT, VO2 will….
Increase exponentially and begin to reach a steady state (Phase II)
At an intensities ABOVE LT, VO2 will….
After approx 3 minutes there is a slow increase in VO2 (SLOW COMPONENT)
- VO2 slow component is slowly increasing during a constant work rate heavier intensity than lactate threshold and it represents a progressive loss of skeletal muscle contractile efficiency.
- The magnitude of slow component is relative to the intensity ABOVE the LT e.g. the higher above the greater the increase
What is Critical intensity?
The highest power output that can be sustained without an increase in VO2 or blood lactate
Denotes the greatest rate of oxidative ATP resynthesis that can be sustained without drawing on W’
Represents the Peak oxidative power output
When does exhaustion occur?
When W’ is fully depleted and no longer available
What is W Prime?
The anaerobic work capacity of the individual that can be done above the critical power
- Amount of energy available in the W’ is limited and rate of exhaustion is proportional to the intensity above critical power
Describe moderate intensity domain
- Intensities below the critical intensity and LT/GET
- Stabilised intramuscular metabolic environment
Describe the Heavy intensity domain
- Intensities above Below the Critical intensity but above LT
- Stabilised intramuscular metabolic environment
- VO2 stabilised with a slow component
Describe the Severe intensity Domain
- Intensities above the critical intensity which rely on the W’ for energy supply
- Unstabilised metabolic environment until reaching VO2max
Describe the Extreme intensity Domain
- Intensities above the critical intensity with a Time to exhaustion < 2mins
- Task failure occurs without reaching the VO2max
What is critical stroke rate?
The point at which stroke biomechanics change as a function of your fatigue
This would be used in swimming
Describe W’bal
Is a model that describes how W’ is discharged and reconstituted during exercise
- Exercising higher than CP –> discharges W’
- Exercising lower than CP –> reconstititutes W’
Relationship between intensity and W’bal
The closer the intensity is to the CP the slower the W’ is discharged/reconstituted
The more aerobically fit you are –> the quicker you can replenish W’
What are the 3 types of fatigue?
Peripheral Fatigue: Muscle-level fatigue due to factors like lactic acid buildup and energy depletion, reducing muscle endurance and strength.
Central Fatigue: Originates in the CNS, reducing brain signal strength to muscles; influenced by psychological factors and prolonged exertion.
Global Fatigue: Combined effect of peripheral and central fatigue, leading to total body exhaustion common in high-intensity, prolonged activities.
What is the cause of fatigue during exercise below CP?
Refer to the 2 domains
Moderate domain - central fatigue primarily
Heavy Domain - peripheral (glycogen depletion) and central mechanisms
What causes fatigue in the Severe domain?
PERIPHERAL FATIGUE DOMINANT –> METABOLITE BUILDUP
Energy Depletion: Rapid use of muscle glycogen and ATP limits sustained contraction.
Metabolic Byproducts: Accumulation of lactate and H+ lowers pH, impairing muscle efficiency.
Neuromuscular Demand: Central fatigue reduces motor unit activation.
Oxygen Limitations: Insufficient oxygen delivery shifts reliance to anaerobic metabolism.
Heat & Dehydration: High heat and fluid loss impair performance and endurance
