Central Fatigue Flashcards
What is the central fatigue hypothesis?
During prolonged exercise the synthesis and metabolism of central monoamines like serotonin, dopamine and noradrenaline are influenced.
The theory around serotonin and central fatigue and the process that occurs.
This neurotransmitter is associated with lethargy and sleepiness so could be linked to perceived exhaustion and fatigue during exercise.
The process:
When glycogen stores are depleted, increased utilisation of FFA and BCAA.
FFA and tryptophan are transported in the blood by the same carrier, albumin.
As FFA level in blood increases it displaces albumin bound tryptophan and increases the conc of free tryptophan in the blood.
Also, the increased utilisation of BCAAs decreases its conc in the blood. BCAAs competes with tryptophan for the same transporter in the brain.
During exercise, the entry of tryptophan into the CNS is favoured due to increased use of BCAAs and elevated plasma FFAs.
The entry of tryptophan into the brain leads to elevated 5-HT levels as tryptophan -> 5-HTP -> 5-HT.
Increased serotonin leads to decreased performance
Why is dopamine linked to central fatigue?
It’s linked to motivation so the individuals sense of effort and willingness to continue exercise is significantly influenced by the CNS.
Why is acute severe hypoxia linked to a reduced exercise performance?
It’s due to a failure of drive from the motor cortex, as a consequence of diminished O2 availability in the brain.
Ie. We need O2 to think
