Metabolic Responses to Sprint Exercises Flashcards
What is a observed where performance can be measured and appropriately compared through historical time?
A clear and steady progression in performance.
Define exercise intensity?
The rate of power production relative to the functional capacity of the individual.
Define exercise duration?
The duration for which a particular exercise intensity is sustained.
Give the exercise intensity domains?
Moderate, heavy, very-heavy, severe.
What are the characteristics of moderate intensity exercise?
No sustained increase in arterial blood lactate and a tolerable duration >3 hours.
What are the characteristics of heavy intensity exercise?
Sustained increase in arterial blood lactate that comes to a steady state and a tolerable duration of ~1-3 hours.
What are the characteristics of very-heavy intensity exercise?
Progressive increase in arterial blood lactate throughout and a tolerable duration of ~2-60 minutes.
What are the characteristics of severe intensity exercise?
Rapid muscle fatigue, limited by the VO2max and a tolerable duration of
What does heterogenous mean in terms of muscles?
Made of fibres with different metabolic, physical and anatomical properties.
Which muscle fibre types are small in size?
Type 1
Which muscle fibre types are large in size?
Type 2x
Which muscle fibre types are highly resistant to fatigue?
Type 1
Which muscle fibre types are the most power and force producing?
Type 2x
Which muscle fibre types contract rapidly
Type 1, 2x and 2a
Which muscle fibre type is most mitochondrial dense?
Type 1
Which muscle fibre type is highly oxidative?
Type 1
Which muscle fibre type is highly glycolytic?
Type 2x
What is the fibre recruitment profile?
The orderly hierarchy of motor unit recruitment from type 1, to type 2a, to type 2x.
Is the relationship between fibre type and metabolic properties fixed?
No.
What does the relationship between fibre type and metabolic properties depend on?
Response to and type of training.
In skeletal muscles what is the [ATP] 5-8mmol/kg enough for?
8 maximal contractions or ~2-3 seconds.
During sprint exercise from what sources is ATP largely from?
Anaerobic: stored ATP, PCr breakdown and glycolysis.
What is cross talk of energy providing pathways?
The contribution of energy derived from alternative pathways integrating.
What are the relative contributions of each energy providing pathways dependent on?
Fibre type; type 1 has a slow decrease in [ATP] whereas type 2x has a large decrease which is protected and maintained.
From high to low, list the storage of carbohydrates, glycogen and fatty acids?
Fatty acids> carbohydrates> glycogen> PCr
What are the fastest routes to provide energy?
Stored ATP and PCr.
From high to low, list the maximum flux of carbohydrates, fatty acids, glycolysis and PCr?
PCr> glycolysis> carbohydrates> fatty acids.
What enzyme breaks down PCr?
Creatine Kinase
What is a quality of creatine kinase?
It is near-equilibrium and has the fastest rate of all other enzymes in the muscle.
What does PCr breakdown buffer?
ADP accumulation
What is thought to be a major cause of muscle fatigue?
Inorganic Phosphate
How was inorganic phosphate found to be a major cause of muscle fatigue?
Using genetically mutated mice with no creatine kinase activity; showed lower absolute force but better maintenance of force due to lack of Pi formation.
What do high rates of ADP accumulation cause?
Slower rates of muscle relaxation which can dramatically inhibit muscle power.
What is excellent at buffering ADP accumulation?
The Lowman reaction
What does MR spectroscopy show sprint to contribute to?
And alkalosis rather than an acidosis.
What is MMCK?
Mechanical machinery creatine kinase
Where is MMCK expressed?
In the cytosol
Where is mitochondrial CK co-localised to?
The adenine nucleotide translocase (ANT)
What rae MMCK and MiCK required for?
Maintenance of the creatine-phosphorcreatine shuffle to communicate between the mitochondrial and myofibril.
What is there close communication between in type 1 and type 2 muscle fibres?
Type 1: PCr and oxidative phosphorylation
Type 2: Glycoslyis and PCr
What two types of buffers is PCr?
A temporal energy buffer, providing rapid ATP provision during sprint exercise when ATP storage is challenged, and a spatial energy buffer, a signalling molecule to communicate with other cellular compartments to increase the rate of ATP production.
What two reactions buffer cytosolic [ATP] during severe intensity exercise?
Adenylate kinase and AMP deaminase
What does AMP accumulation play an important role in stimulating?
Glycogen phosphorylase and PFK
When is AMP deaminase inhibited?
When [ATP] is high
What is IMP an allosteric activator of?
Glycogen phosphorylase
What do type 2 muscle fibre have greater of?
[PCr], glycogen content, glycogen phosphorylase activity, AMP deaminase activity, a-glycerophosphate shuttle expression.
Is glycolytic flux dependent on the oxygen availability in type 2 muscle fibres?
No, but in type 1 it is.
