Integration of exercise metabolism Flashcards
5 things that can happen to pyruvate
- Reversible conversion to lactate (Anaerobic glycolysis)
- Conversion to acetyl CoA or oxaloacetate and oxidation through the citric acid cycle
- used in gluconeogenesis to resynthesise glucose
- Conversion to alanine, linking carbohydrate and protein metabolism
fat oxidation
- what 2 things can triacylglycerol be hydrolysed to
- what can glycerol be used for
- what is glycerol 3 phosphate required for
- what are fatty acids converted to
- what 2 things can acyl coA be used for
- fatty acids and glycerol
- first step in gluconeogenesis into glucose
- also required for triacylglycerol synthesis
- acyl coa through beta oxidation
- can enter the krebs cycle or be used in triacylglycerol synthesis
proteins
- what are proteins hydrolysed to
- what are these things converted to
- what are they used for
- amino acids
- urea, pyruvate, acetyl coa, compounds of the citric acid cycle
- yield energy or used in synthesis of glucose or fatty acids
which energy system uses carbs, lipids and proteins as food fuel
aerobic system
Which energy source and when, depends on….
○ Exercise parameters (Frequency, intensity, time, type)
○ Male/ Female
○ Age (Mitochondrial function which reduces with age)
○ Nutritional status
○ Training state (Health)
○ Genome (muscle fibre type)
○ Environmental factors (Ambient temperature and oxygen availability)
exercise intensity and energy source
- what is the source at low intensity
- source at moderate intensity
- what happens to use of CHO and lipid between 40-70% VO2 max
- does fat oxidation increase or decrease as duration increases
- source at maximal intensity exercise
- Low rate of ATP synthesis from breakdown of triglycerides is sufficient for the low rate of ATP breakdown at rest.
- As exercise intensity increases to intensity that can be maintained, Pi, ADP, AMP, Ca2+ and epinephrine rise to stimulate breakdown of CHO and lipid.
- Use of CHO and lipid changes at between 40-70% VO2max, with a reduction in lipid usage and more CHO
- increases
- initially PC for first 10 seconds, then glucose and glycolysis
the basic process of carb loading
○ Days 1-4 Lowering glycogen content intake (40% of macro) to increase glycogen synthase which decreases muscle glycogen content
○ Then 2-3 days of excess carb intake (70% of macro) causing muscle glycogen to increase above original baseline so more for the race increasing time to exhaustion
what is the impact of CHO intake during endurance events
- can increase time to exhaustion
- in research, the Control group was exhausted after approximately 3 h, and the contribution of carbohydrates to energy production had fallen below 30%. Athletes who took CHO - could cycle for an additional hour, and carbohydrates still contributed half of the total energy.
chronic fat loading pre exercise
- how its done
- adaptions
- impact on fat max and maximal fat oxidation
- more of a long term lifestyle strict diet control
○ increase in myocellular triacylglycerols
○ increased uptake of plasma fatty acids by the active muscles
○ Increased use of plasma triacylglycerols for energy production - The plasma concentration of ketone bodies rises (the name ketogenic diet)
- the muscle and liver glycogen stores drop or do not change.
- increase, up to 80% of VO2 max and 1.6 g/min–1, respectively.
carnitine
- what is it needed for
- how does it do that
- what does exercise do to demand
- what is the problem
- fa entry to mitochondria
- Acetyl CoA and carnitine form acetylcarnitine and CoA for entry
- increased as there’s more acetyl coa
- stores a limited so deplete and limit the entry of lipids to the mitochondria
fat intake during exercise
- what fat should you ingest
- how does fat intake benefit during exercise
- limitations
- Medium-chain triacylglycerols (MCT)- absorbed faster than LCT, with no need for carnitine transport across the mitochondrial membrane where they’re used in beta-oxidation
- longer time for CHO stores to deplete delaying fatigue, as able to use fat at a higher intensity (fat stores don’t deplete, glycogen does
- not as good as carbs, can cause gastrointestinal problems
how can we measure energy source being used during exercise
- what ratio is used
- what does the value produced mean
- respiratory exchange ratio (RER) - volume of expired CO2 divided by the o2 consumed
- Closer to 1 is pure CHO oxidation, 0.7 pure fat oxidation
- Above 1, eg. If 1.3 in anaerobic systems
metabolic flexibility
- what is it
- 2 key aspects (fasting and fed state)
- what is associated with high flexibility
- the capacity for the organism to adapt substrate oxidation to fuel activity
- switch to lipid oxidation and fatty acid oxidation during fasting where have low o2 availability
- suppress lipid and increase glucose uptake, oxidation and storage under fed state
- associated with faster switch, eg. can adapt do a different diet faster
impact of endurance training on energy sources used during exercise
- 2 main aims
- benefits for the contribution of lipids
- impact
- cause of the improvements in VO2 max
- improve cardiorespiratory fitness which will improve endurance
- use lipids at higher intensity, sparing glucose which can be used at a higher intensity
- increase muscle mitochondria, decrease glucose uptake, decrease glycogenolysis, increase fatty acid uptake
- more due to the cv adaptions, not energy source
adrenaline
- what is the purpose in exercise regarding fuel source
mobilise energy sources into the bloodstream (glucose, fatty acids)
