Central + Peripheral Fatigue and Pacing

Question 1

What are the causes of fatigue?

Answer 1

• Failure to supply enough oxygen
• Failure to keep lactate levels down
• Failure to keep phosphate or hydrogen ions down
• Depletion of glycogen
• Failure to lose heat, threat to homestatic control.

Question 2

What is central fatigue?

Answer 2

Failure of the central nervous system to adequately drive the muscle

Question 3

What is peripheral fatigue?

Answer 3

An impairment located in the muscle characterised by a metabolic end point

Question 4

What is the difference between Afferent and Efferent feedback?

Answer 4

Afferent = Driving stimuli via sensory neurons from the muscle to the CNS. ‘Affect of exercise’
Efferent = Driving stimuli from the CNS to the muscle
‘How can we effect the muscle’

Question 5

What are the main components which cause central fatigue?

Answer 5

• Disturbances in brain neurotransmitters, such as serotnin (increased = fatigue), norepinephrine, dopamine (decreased = fatigue)
• Depletion of brain glycogen
• Increases in brain and core temperature

Question 6

What are the main components which cause peripheral fatigue?

Answer 6

• Depletion of substrates (ATP, PCr, Glycogen)
• Accumulation of metabolites such as Hydrogen ions
• Feedback from fatigue sensitive muscle afferents - relay exercise induced metabolic disturbances to the CNS

Question 7

Is there a limit or threshold to fatigue?

Answer 7

Amann 2011, reported there was a limit to fatigue this was shown through pre-existing exercise had substantial adverse effect on CMD and power output.

Question 8

What did Amann report when peripheral feedback was reduced?

Answer 8

Increased EMG activity = stronger drive to perform when not receiving peripheral feedback.
However there was still greater CV response and respiratory response to exercise = without afferent feedback athletes would become exhausted

Question 9

According to Amann what did the findings highlight in regards to afferent feedback?

Answer 9

Afferent feedback has a crucial role to the central drive in pacing during an event. Efficient and effective pacing = less fatigue.

Question 10

What is a pacing strategy?

Answer 10

Defined as the distribution of work rate throughout an exercise bout and largely influences the success or failure of the performance. Pacing comes in to play to ensure you can achieve maximum performance without loss of cellular homestasis.

Question 11

Which factors may potentially alter a pacing strategy?

Answer 11

Nutritional status, Surface, Course conditions, Climate conditions, Opposition, Psychological status