Metabolic Adaptations to Endurance training Flashcards
What is the hallmark of endurance training?
To increase VO2 max.
What is the most important metabolic adaptation in response to endurance training?
To increase the ratio of lipid to carbohydrate used during prolonged exercise.
What are the 4 ways in which endurance training modifies the proportion of energy sources used during exercise?
1) Muscle mitochondrial content increases
2) Fatty acid uptake increases
3) Rate of glycogen breakdown decreases
4) Glucose uptake decreases
What does mitochondrial content increasing mean in the muscle?
Enhances the capacity of muscle to synthesize ATP from aerobic breakdown of carb and fat.
How does fatty acid uptake increase as a result of endurance training?
Because of increased capillary density and lipoprotein lipase in muscle. These facilitate delivery and hydrolysis on lipoprotein-bound TG to be used in exercising muscle.
What does ‘rate of glycogen breakdown decreasing’ mean?
Endurance training increases muscle glycogen content, but decreases breakdown, which reduces production of AMP + Pi.
This is important as these are allosteric regulators of glycogen phosphorylase.
What does reduced carbohydrate usage mean in terms of lactate production?
It diminishes lactate production, therefore causing a delay to reach lactate threshold (marker of fatigue).
How does endurance training increase VO2 max?
Circulatory adaptations
- Increased erythrocytes (increased haemoglobin)
- Increased stroke volume hence increased maximal cardiac output.
What are the mechanisms by which endurance training increases muscle glycogen content?
- Increased insulin action
- GLUT4
- Hexokinase
- Glycogen synthase
What effect does endurance training have on IMTG content and location?
Endurance training increases IMTG content, with IMTG locating closely to the mitochondria in muscle
What affect does endurance training have on mitochondria?
Increases mitochondria number and size. Also increases the amount of mitochondrial proteins.
‘Endurance training increases oxidative enzymes in mitochondria’. What are these enzymes?
Complex I-III and Citrate Synthase
What affect does endurance training have on plasma lipid profile?
- 5-9% reduction in plasma TG conc.
- 2% reduction in cholesterol, 3% reduction in LDL
- 2-3% increase in HDL
What is the relationship between glut4 and muscle glycogen accumulation?
Higher levels on GLUT4 correlates with higher muscle glycogen accumulation.
What is the difference in fibre types between TR and UT individuals?
% of type I is greater in TRN than UT individuals, % of type IIb was less in TRN than UT. No difference in IIa fibres.
What happened to plasma insulin, plasma C peptide, and plasma glucose after training?
All decreased.
What is IMP?
If rate of ATP resynthesis is behind rate of ATP breakdown, ADP and AMP accumulation occur. AMP activates AMP deaminase, product of this reaction = IMP.
IMP = marker of imbalance between ATP resynthesis and breakdown.
What is increase in body temperature associated with and why?
Fatigue. Direct effect of hypothermia on CNS or muscle function. Also of hypothermia and any dehydration on CV function, ability to maintain optimal cardiac output and O2 delivery to muscles.
What are the 6 characteristics of an endurance athlete?
- High VO2 max
- Ability to maintain high %VO2 max.
- Higher power output at lactate threshold (muscle oxidative capacity)
- Fatigue resistance
- Efficient/economical technique
- Ability to oxidise fat at high power outputs.
What happens to K+ balance after prolonged exercise?
There is a progressive release of K+ from contracting skeletal muscle, manifesting itself as a slow rise in arterial plasma K+.
There is a slight reduction in intra-muscular K+ levels, may be enough loss to impact excitability of sarcolemma during prolonged exercise.
