Lecture 7: Fatigue

Question 1

Sources of fatigue

Answer 1

• Prolonged task execution
• Other activities
• Lack of sleep
• Chronic fatigue

Question 2

Types of fatigue

Answer 2

• Peripheral/physical

- Central/mental

Question 3

Hill (1920s) - peripheral fatigue

Answer 3

• Fatigue is caused by limited capactiy of the heart
  = oxygen demands of muscles exceeds limited capacity of heart
  -> accumulation of lactic acid -> fatigue
• That fatigue resides in the periphery

Question 4

Mosso (1892) - central vs. peripheral fatgie

Answer 4

• Hypothesis fatigue in muscle & brain (stops activating muscles)
• Sent electrical stimulation to muscles = doesn’t include brain
• Got participant to move finger until could not (fatigued) = involving muscle + brain
  = got fatigued sooner than in other condition
  = central fatigue/’willpower’ (to drive the muscle)

Question 5

Peripheral fatigue and performance

Answer 5

Possible mechanisms:
- Decreased firing rates of motorneurons
- Reduced conduction along muscle membrane
- Depletion of energy stores (muscle glycogen)
- Lactic acid (blood lactate)
Mechanisms occur with prolonged activation but cannot explain motor failure = these processes would not have reached their limit
- Q1) is fatigue a stop emotion?
- Q2) can it be overriden?

Question 6

Central command & performance under fatigue

Answer 6

• Fatigue is a brain-derived emotion which makes sure that exercise is conducted within biological limit

Question 7

Exercise intensity & attention

Answer 7

1) Internal/association
2) External/dissociation
- High fatigue = ‘attention drawn inwards to monitor bodily process’
- As intensity increases, movement from dissociative => associative focus

Question 8

Fatigue, motivation & endurance performance (Marcora & Staiano, 2010)

Answer 8

• If outcome more important, should be able to overcome fatigue and keep going
• Performed time to exhaustion test, going at 80% max. output
• Did max. power test before & after = were able to produce high power output after being fatigued
• Muscle fatigue cannot explain exhaustion -> motivation!

Question 9

Barte et al (2019)

Answer 9

• Pretest -> fatigue protocol ->(motivation vs. control) posttest
• 60 amateur soccer players
• Fatigue before pretest = 3.8
• Fatigue before posttest = 8.1
• Motivation counteracts negative effects of fatigue = sustained motivation since pre-test
• Motivation group = faster + maintain accuracy