19-22. Metabolic Adaptations to Exercise Flashcards
What is muscle atrophy?
Diminished capacity to generate or maintain power in response to reduced physical activity
What is muscle hypertrophy?
Enhanced capacity to develop maximum strength and power following resistance training
What is increased oxidative metabolism?
Enhanced capacity to maintain power for long periods of time following endurance exercise –> increased oxidative metabolism
How are adaptations readily reversible?
When the stimulus for adaptation is diminished or eliminated
Define genotype.
Underlying genes that are expressed
Define phenotype.
Outward, observable characteristics of a muscle
How does a change in gene expression results in an altered phenotype?
Altered gene expression –> protein structure of a muscle is altered –> phenotype of muscle has been changed
What is meant by the statement: “the adaptive response of muscle is specific to the type of exercise”?
Aerobic vs. anaerobic exercise will result in diff adaptations in muscle metabolism
What comprises endurance training?
- High activation frequency of motor units
- Low force output
Name some of the adaptations to endurance training?
- Increased hexokinase activity
- Size, # of mitochondria
- Increase in all mitochondrial enzymes proportionate to increase in mitochondrial density
- Increase in intramuscular glycogen & lipid stores
- Increase in sarcolemmal FA transport proteins
Why does the lactate threshold occur at a higher intensity of exercise following endurance training?
- More fibers are now FOG –> better oxidative capacity –> muscles don’t have to utilize anaerobic glycolysis (to produce lactate) to meet ATP demands
- Accumulation of lactate in blood doesn’t occur til higher work rate
What adaptations occur in the muscle to increase fat utilization during endurance exercise?
- Higher conc of FFA in blood
- Higher FFA uptake
- Able to metabolize fat @ higher rate
What is the training effect?
Attenuated response at same work rate
What is the major adaptation to resistance training?
Increase in fiber CSA
How does the training effect affect the cross over point between fat and CHO metabolism?
- Shifts cross over point to the right
- Able to use fat metabolism @ higher workloads before switching to CHOs
What are the training-induced changes in muscle fiber type for deconditioned athletes? Conditioned? Endurance?
- Deconditioned = decreased oxidative capacity
- Conditioned = increased oxidative capacity of type I and IIa fibers
- Endurance = increased oxidative capacity for all fiber types b/c type IIx (FG) fibers adapted to have oxidative capacity
How do type IIa fibers adapt to greater loads? Why?
Don’t adapt much for greater loads b.c they’re fully recruited at the lightest load already
The increase in maximal oxygen uptake in muscles is due to what 2 factors?
- Increased cardiac output
- Increased oxygen extraction by muscle
What factors cause QO2 (respiratory capacity of muscle) to increase w/ training?
- Increased mitochondria w/ increased oxidative enzymes
- Increase in capillary density
How are intermyofibrilar mitochondria better than subsarcolemmal mitochondria?
- IMG has 2.5 fold greater respiration rate than SS
- IMF can produce 2-fold greater ATP than SS
What are the enzymatic adaptations to anaerobic training?
- Minimal increases in phosphagen and glycolytic system enzymes
- No increase in TCA, ETC, or fat metabolizing enzymes
What is resistance training?
Increase in the frequency of recruitment of motor units and a significant increase in the load against which motor units contract
Muscle mass is determined by the balance between what 2 processes?
- Protein synthesis
- Protein degredation
What is the key variable of muscle force production?
of cross bridges activated
