11. Skeletal Muscle Adaptation to resistance and endurance exercise Flashcards
what are the differences between growth and proliferation? (muscle vs cancer)
Growth:
- Developmental
- Hypertrophy
- Physiological response
- Adaptation following loading stimulus
- Results in an increase in skeletal muscle mass via an increase in cross-sectional surface area
Proliferation:
- Developmental
- Increase in cell number not cell size
- Pathological not physiological
- Important for regeneration, healing tumour progression
- Uncontrolled
What is the importance of skeletal muscle mass for health?
maintains independence and functionality. If atrophy occurs you lose organelles, cytoplasm and proteins which will decrease the efficiency of the cell functions, you don’t just decrease in size.
What are the multiple disease models associated with a reduction in skeletal muscle mass?
Diabetes, cancer, cachexia, HIV/AIDS, chronic renal failure.
What are the morphological characteristics of hypertrophy?
Cell size is determined by as balance between new protein accumulation and degradation of existing proteins
what are the 3 mechanisms in which hypertrophy can be activated on skeletal muscle?
- Hormonal/ growth factors
- Mechanical loading
- Ingestion of Branch Chain Amino Acids
What is atrophy?
A decrease in cell size mainly caused by the loss of organelles, cytoplasm and proteins.
Explain the role of Molecular Regulation of Growth. Why does is do what it does?
mTOR complex 1 has an effect on hypertrophy. If there is no mTOR1 activity then there is no increase in protein synthesis after acute resistance exercise.
This is because mTOR senses alteration in ‘pro-growth’ signals in the skeletal muscle and will initiate protein synthesis and hypertrophy
What are the 3 main determinants of endurance performance?
- Aerobic enzyme activity
- % of slow twitch fibres
- Muscle capillary density
what is mitochondrial biogenesis?
= the adaptive response of mitochondria to physiological stimuli.
= an increase in mitochondrial number, function and capacity
How does endurance exercise lead to altered mitochondrial biogenesis?
Signal, sensor, mediator process within the muscle .
SIGNAL - muscle contraction which increases substrate turnover and metabolites generation - altering the cellular environment.
SENSOR - energy sensing proteins respond to alterations in these factors, initiation cellular adaptation
MEDIATOR: Gene + proteins are activated to support the metabolic demands of skeletal muscle, increasing fibre-type transformation and mitochondrial biogenesis
What are the molecular cues that link contraction to adaptation?
AMPK activation induces mitochondrial biogenesis via PGC1a. It does this by sensing a change in intracellular energy status and contraction
How does endurance training alter skeletal muscle morphology?
by change in muscle structure, architecture and mitochondrial content
