The Physiology of Training: Effects of aerobic and anaerobic training (part 2) Flashcards
Endurance training results in numerous adaptations in muscle fibres that assist in maintaining homeostasis, what are these?
- Shift in muscle fibre type (fast-to-slow) and increased number of capillaries.
- Increased mitochondrial volume.
- Training-induced changes in fuel utilization.
- Increased antioxidant capacity.
- Improved acid-base regulation.
Endurance training promotes a shift of fibre types in which direction?
fast-to-slow shift + increased capillarisation
What is the magnitude in muscle fibre type change determined by?
Duration of training, type of training, and genetics.
There is an increased number of capillaries surrounding muscle fibres as a result of endurance training. What does this cause?
*Enhanced diffusion of oxygen.
* Improved removal of wastes.
What is the significance of increased mitochondrial volume and turnover in skeletal muscle?
- Increased mitochondrial volume = greater capacity for oxidative phosphorylation
- Decreased cytosolic [ADP] due to increased ADP transporters in mitochondrial memb.
What does more ADP transporters in mitochondrial membrane result in?
- Less lactate and H+ formation.
- Less PC depletion.
What is the influence of mitochondrial volume on cytosolic ADP concentration during submaximal exercise?
- Increases in the number of ADP transporters in mitochondrial membrane
= faster ADP uptake into mitochondria and lower cytosolic [ADP] - Endurance exercise training-reduces the O2 deficit at the onset of work
Faster rise in O2 uptake = less lactate formation, less PC depletion
What changes in fuel utilization does endurance training cause?
- Increased utilization of fat and sparing of plasma glucose and muscle glycogen.
- Plasma glucose vital fuel source for CNS
- Intramuscular fat provides ~50% of lipid oxidized during exercise, plasma FFA provides the remainder.
Endurance training adaptations improve plasma FFA transport and oxidation, how?
- Increased transport of FFA into the muscle (from plasma)
- Transport of FFA from cytoplasm to mitochondria
- Mitochondria oxidation of FFA
Contracting skeletal muscles produce free radicals. What do these do?
- Radicals chemical species/molecule that contain unpaired electron, making them highly reactive and can damage proteins, membrane and DNA.
- Radicals promote oxidative damage and muscle fatigue
Endurance Training Improves the Antioxidant Capacity of Muscle
How does Endurance Training Improve the Antioxidant Capacity of Muscle?
Training increases endogenous antioxidant enzymes.
- Improves the fibres ability to remove radicals.
- Protects against exercise-induced oxidative damage and muscle fatigue
How does endurance training improve acid-base balance during exercise?
Training adaptations.
- Increased mitochondrial number. (Less carbohydrate utilization = less pyruvate formed.)
- Increased NADH shuttles (via ETC)
(Less NADH available for lactic acid formation.)
- Change in LDH isoform.
(M4 → M3H → M2H2 → MH3 → H4)
(Heart form (H4) has lower affinity for pyruvate = less lactic acid formation.)
What is the relationship between endurance/resistance training and protein synthesis?
Endurance and resistance exercise training promotes protein synthesis in fibres.
- Exercise “stress” activates gene transcription
What is the process of training-induced muscle adaptation?
- Muscle contraction activates primary and secondary messengers.
- Results in expression of genes and synthesis of new proteins.
- mRNA levels typically peak in 4 to 8 hours, back to baseline within 24 hours.
- Daily exercise required for training-induced adaptation.
Primary and Secondary Signalling Pathways Interact to Promote Exercise-Induced Adaptations. Name 4 primary signals.
- Mechanical stretch (resistance training).
- Calcium (endurance training).
- AMP / ATP (endurance training).
- Free radicals (endurance training)
