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HMS, BM EQ-Bank 766

A swimmer completes a 200-metre freestyle race and feels significant muscle fatigue in the final 50 metres. Analyse the physiological causes of this fatigue and how it affects performance.   (5 marks)

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Sample Answer

  • The 200-metre freestyle predominantly uses the glycolytic energy system, with increasing aerobic system contribution toward the end of the race.
  • The primary cause of fatigue is the accumulation of lactic acid in the working muscles, which occurs when production exceeds the rate of removal.
  • Lactic acid accumulation reduces the muscle’s ability to contract forcefully by disrupting calcium binding and cross-bridge formation in the muscle fibres.
  • The increasing acidosis in the muscle environment affects enzyme function, reducing the rate of ATP production through glycolysis.
  • The swimmer experiences a noticeable decline in stroke efficiency and power output as muscle fibre recruitment patterns change in response to fatigue.
  • Coordination and technique deteriorate in the final 50 metres as the central nervous system adapts to the changing muscle fibre capabilities.
  • The perception of effort significantly increases as the body requires increased nervous system activation to maintain the same power output with fatiguing muscles.
Show Worked Solution

Sample Answer 

  • The 200-metre freestyle predominantly uses the glycolytic energy system, with increasing aerobic system contribution toward the end of the race.
  • The primary cause of fatigue is the accumulation of lactic acid in the working muscles, which occurs when production exceeds the rate of removal.
  • Lactic acid accumulation reduces the muscle’s ability to contract forcefully by disrupting calcium binding and cross-bridge formation in the muscle fibres.
  • The increasing acidosis in the muscle environment affects enzyme function, reducing the rate of ATP production through glycolysis.
  • The swimmer experiences a noticeable decline in stroke efficiency and power output as muscle fibre recruitment patterns change in response to fatigue.
  • Coordination and technique deteriorate in the final 50 metres as the central nervous system adapts to the changing muscle fibre capabilities.
  • The perception of effort significantly increases as the body requires increased nervous system activation to maintain the same power output with fatiguing muscles.