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HMS, BM EQ-Bank 764 MC

During a 200-metre sprint, an athlete experiences significant fatigue in the final 50 metres. Which of the following best explains the primary cause of this fatigue?

  1. Depletion of phosphocreatine stores
  2. Accumulation of lactic acid in the muscles
  3. Depletion of muscle and liver glycogen
  4. Increased use of fat as a fuel source
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\(B\)

Show Worked Solution

Consider Option B: 

  • In a 200-metre sprint (lasting approximately 20-30 seconds), the glycolytic system is the predominant energy system.
  • The primary cause of fatigue is the accumulation of lactic acid in the muscles, which occurs when lactic acid is produced faster than it can be removed, interfering with muscle contraction.

Other Options:

  • A is incorrect: While PCr stores are depleted during the sprint, this occurs within the first 10-15 seconds and is not the primary cause of fatigue in the final stages of a 200m race.
  • C is incorrect: Glycogen depletion is a cause of fatigue in longer duration activities (typically > 60 minutes), not in short-duration, high-intensity events like a 200m sprint.
  • D is incorrect: Increased fat metabolism is associated with longer endurance events and is not a cause of fatigue in sprint events; fat metabolism actually increases during recovery, not during the sprint itself.

\(\Rightarrow B\)