Fatigue and Pacing Flashcards
Explain fatigue and give some examples of the causes
Fatigue is the failure of the skeletal muscles to perform at the required capacity due to reaching a limit of performance, lack of fuel, increased H+ ions causing acidosis, lactate accumulation, decreased oxygen supply, increased phosphate, failure to lose heat
Explain central fatigue
A failure of the central nervous system to adequately drive the muscle, disturbances in brain neurotransmitters and higher serotonin paired with decreased dopamine leading to fatigue, depletion of brain glycogen, increase in core and brain temperature which reduces drive of CNS
Explain peripheral fatigue
Impairment located in the muscle characterized by a metabolic end point, depletion of glycogen and ATP, accumulation of H+ ions causing acidosis, accumulation of inorganic phosphates, feedback from fatigue-sensitive muscle afferents (group III/IV) relay exercise induced metabolic disturbances to central nervous system, acts as regulator for exercise
What happens when peripheral fatigue is blocked?
Peripheral fatigue acts as a regulator for exercise, blocking it causes a greater drive to perform from the central nervous system, greater cardiovascular and respiratory response to exercise = greater central motor drive, significantly lower overall power output and metabolic rate due to early fatigue, highlights crucial role of afferent feedback in pacing
Explain the importance of pacing and feedback on sports performance
Pacing is the distribution of work rate throughout exercise which largely influences success or failure of performance, afferent feedback informs central nervous system of fatigue or lack of fatigue in order to make decisions on pace/effort, external performance feedback is about making strategic decisions on pace/effort based on external factors during performance, initial pacing based on anticipatory feedforward algorithm which then changes based on afferent feedback and external performance factors
Explain the characteristics of transient fatigue
Up to 80 minutes after exercise, main causes are acidosis, substrate depletion, electrolyte disturbance, dehydration
Explain the characteristics of acute fatigue
From 80 minutes to 72 hours after exercise, main causes are micro trauma caused by eccentric muscle actions during running, blunt trauma from tackles/collisions
Explain the characteristics of chronic fatigue
Fatigue that lasts longer than 72 hours post-exercise, main causes are inadequate recovery, excessive training/playing work load/volume, external factors
Discuss the use of questionnaires in measuring fatigue
Measure muscle soreness, fatigue, mood and sleep quality. Unknown reliability. Easy to do and sensitive to changes in performance. Subjective so players can easily manipulate answers. Record weekly within 2-3 days post-match (depending on training)
Discuss the use of blood-borne markers in measuring fatigue
Measures creatine kinase, testosterone/cortisol and glutamate/glutamine. Varied reliability. Useful to understand mechanisms of fatigue and health status. Costly, invasive and poor temporal relationship with performance and perceptual change. Only measure when other markers suggest investigation of health status
Discuss the use of neuromuscular performance in measuring fatigue
Measure countermovement jump flight time, force and power. Good reliability. Indirect marker of fatigue and can easily be embedded into training programme. Difficult to identify match-specific fatigue. Record weekly, 2-3 days post-match (depending on training)
Discuss the use of performance tests in measuring fatigue
Measure running velocity. Good reliability. Can identify match-specific fatigue. Time consuming and can cause additional fatigue. Use when other markers suggest fatigue or when returning from injury
