Week 9 - Physiology of Training Flashcards
What are the key things to consider when training
Source of energy and muscle fibre recruitment used for force production
What are the principles of training
Overload: Training effect occurs when a phyisological system is exercised at a level beyond which it is normally accustomed
Specificity: Training effect is specific to:
1. Muscle fibres
2. Energy system involved
3. Velocity of contraction
4. Type of contraction
Reversibility: Gains are lost when training ceases
What effects does endurance training have on VO2 max
Increases VO2 max
Average increase = 15-20%
Smaller increases in individuals with high VO2
Up to 50% in low VO2 max
Difference between short and long adaptations of exercise-induced improvements of VO2 max
Short: Increase in SV and cardiac output
Long: Increase in SV, and a-vO2
How does endurance training increase stroke volume
Increases preload (plasma volume and venous return)
Decreases afterload (aterial constriction)
Increases contractility (greater force from each contraction)
Why is heart rate lower following training
Increased stroke volume compensates for it
Resting HR lower after training because of vagal tone increased, allowing for greater filling time
How does training increases arteriovenous O2 difference
- Muscle blood flow increases (Decreases sns vasoconstriction and increase diameter of arteries)
- Improved ability of muscle fibres to extract and utilise O2 from the blood (increased capillary density and mitochondrial number)
- Increased capillary supply and oxygen delivery in trained muscle
What difference do vascular remodelling and muscle metabolic changes make to muscle blood flow in exercise
Blood flow is lower during submaximal exercise because the a-V difference is greater
Blood flow is higher during maximal exercise
What adaptations in muscle fibre occurs in maintaining homeostasis from training
- Shift in muscle fibre type and increased number of capillaries
- Increased mitochondrial volume
- Training-induced changes in fuel utilisation
- Increased antioxidant capacity
- Improved acid-base regulation
How does endurance training promote a shift in muscle fibre type and capillary density
Reduction in fast fibres and increase in slow fibres
Increased number of capillaries surrounding muscle fibres
How does endurance training increase mitochondrial volume and turnover
Increases volume of both subsarcolemmal and intermyofibrillar mitochondria (80%)
Increases in number of ADP transporters in mitochondria membrane = faster ADP uptake into mitochondria and lower cytosolic
How does endurance training induce changes in fuel utilisation
Increased utilisation of fat and sparing plasma glucose and muscle glycogen
Increased transport of FFA into muscle, from cytoplasm to mitochondria, and mitochondrial oxidation of FFA
How does endurance training improve antioxidant capacity of muscle
Contracting muscle produces free radicals = Training increases endogenous antioxidants enzymes
How does endurance training improve acid-base balance during exercise
- Increased in mitochondria leads to increased FFA oxidation and decreased PDK activity and increased mitochondrial uptake of pyruvate and NADH
- Increased FFA oxidation and decreased PFK activity lead to decreased pyruvate formation
- Increased mitochondrial uptake of pyruvate and NADH, decreased pyruvate formation, and increased H4 form of LDH leads to decreased lactate and hydrogen ion formation which ensures that blood pH is maintained
When do mRNA levels typically peak from training-induced muscle adaptation
4-8 hours, back to baseline within 24 hours.
Daily exercise required for training-induced adaptation
What are some secondary messengers in skeletal muscle
AMPK (glucose uptake)
p38 (Important signalling)
PGC-1a (mitochondrial biogenesis, promotes angiogenesis, synthesis of antioxidant enzymes)
CaMK (activation of PGC-1a)
Phosphatase (muscle fibre regeneration and shift)
NFxB (synthesis of antioxidant enzymes)
mTOR (protein synthesis and muscle size)
What are some primary signals to intracellular signalling in response to exercise
Resistance: Mechanical stretch
Endurance: Calcium, AMP/ATP, Free radicals
What biochemical changes in HR and ventilation occur due to endurance training
HR and ventilation reduced due to reduced feedback to cardiovascular control centre and number of motor units recruited