Lecture 7 - Lipid metabolism during exercise Flashcards
Pyruvate can also turn into ____
Lactate
As you increase the power output, the concentration of lactate in the blood willl…
increase slowly and then at higher intensities will increase quite dramatically
What happens if you exercise above and below the lactate threshold?
Below: blood lactate will level off, any decrease slightly
Above: continuous rise in lactate
Lactate is produced even below the…
maximum oxygen uptake
I.e the hypoxia is not the reason pryuvate is forced down the path towards lactate
The production of lactate is determined by the
Balance between the rates of pyruvate formation and the rates of pyruvate oxidation (of course there are factors that affect both of these)
List the factors involved in the regulation of lactate metabolism during exercise:
Production determined by balance between rates of pyruvate formation and oxidation
Blood levels determined by rates of lactate production and clearance
Muscle oxidative capacity
LDH isoenzymes favours the production of lactate (more = more lactate for a given amount of pyruvate)
o(2) supply to contracting muscle - If you hold your breath and exercise you’ll produce more lactate
Adrenaline - increases the rate of glycogen breakdown - will see more lactate
Muscle [glycogen] - more glycogen broken down = more lactate
The lactate threshold is used as a measure in sports science because…
provides a measure of the muscle oxidative capacity without having to take a muscle biopsy and measure the mitochondria
Following a period of training, what will be the effect on lactate?
low blood and muscle levels - one of the hallmarks of training
Fats can only be oxidised meaning their metabolism is only…..
aerobic
The power output from fat oxidation is lower than…
the output from carbohydrate oxidation
After exercise and training, if you have a fatty meal you’re better able to …
remove triglycerides from the bloodstream as they go into the muscle
Here they are more likely to be oxidized so that’s why it is a good way to regulate fat mass
Lipolysis is usually measured from the appearance of..
glycerol
There is a reciprocal relationship between FAs from adipose tissue and
FAs from muscle - When you prevent the FAs release from
What does the hormone sensitive lipase (HSL) do?
breaks down triglycerides
sensitive to hormones that mobilise glycerol
monoglyeride (MGL) lipase…
breaks down FA and cleaes off glycerol
What is responsible fot he regulation of adipose tissue lipolysis during exercise?
It is mediated by apipose triglyceride lipase (ATGL) and hormone sensitive lipase (HSL)
Beta-adrenergi stimulation
decease in insulin - an anabolic hormone
adipose tissue blood flow - during exercise this is reduced, so less enters the blood stream
FFA/albumin ratio - albumin is the most abundadnt plasma protein which has binding sites for FAs
Blood (glucose) and lactate - decreases lipolysis
Caffeine - probably acting via adrenaline - mobilise FAs.
How is lipolysis regulated with the muscle?
mediated by adipose triglyceride lipase (ATGL) and hormone sensitive lipase (HSL)
B-adrenergic stimulation (via PKA) - Adrenaline
ERK (activated by Ca2+) - another kinase
AMPK inhibits HSL activation - AMPK promotes energy breakdown (a bit counter-inituitive, reason not known)
Blood (glucose)
plasma FFA availability
What are the determinants of muscle FA uptake?
Arterial plasma (FAs)
Ability of muscle to oxidise FAs - maintain lower intracellular conc. and maintain diffusion gradient
FA transporter (FABP,CD36, FATP)
Carnitine (helps get them across the mitochondrial membrane), CPT activity
Beta-oxidative capacity (HAD: an ezyme involved in the first step in Mitochondria breakdown of FA) - more mitochrondria, more breakdown
What are the means of msucle FA uptake?
1- simple diffusion
2 CD36 and FABP act to enhance local (FA) for diffusion
- CD36 and FABP facilitate FA uptake
- FA uptake via FATP
- Long chain FA uptake via FATP
Carnitine can act to…
facilitate FA uptake into the mitochondria
a credible “fat”drug
carnitine can act as a buffer for an increase in
glycolytic rate (exercise intensity)
The more HAD you have in the muscle, the greater your
FAT oxidation - will burn more fat
Therefore when you exercise more = increase in mitochondria - increase in HAD = will burn more fat over a day
Which intensity is there maximum fat oxidation?
25% Vo2MAX
Why is FA oxidation reduced with increasing exercise intensity?
reduced plasma FA availability
Increased glycolytic flux inhibits CPT activity and mitochondrial FA uptake (malonyl-CoA?, pH)
Reduced carinitine availabilty
(oxidation of CHO requires less O2 for given ATP production)
Medium chain Triglycerides don’t need ____ to get in to the mitochondria
CPT - can be oxidised easier
from 40-80% VOC2 peak, what happens to long chain, and medium chain triglycerides?
long chain - goes down
medium chain - doesn’t change (will be added to sports supplements)
How does training effect lipid metabolism
trainsed has a greater FA uptake and oxidation (muscle uses more triglyceride)
Trained muscle has a greater capacity for fat oxidation, using FAs from blood and FAs from muscle triglyercides (the latter to a greater extent)
What is the adaptation to trained muscle which makes FA oxidation better?
Increase the amountof CPT and the abililty of FAs transported into the mitochondria
