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Glycogen depletion — MRCP Part 1 MCQ

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HardExercise PhysiologyGlycogen depletionMRCP Part 1

A 29-year-old male endurance cyclist has declining performance, recurrent metatarsal stress injuries, reduced libido and fewer morning erections. BMI is 21 kg/m². Testosterone and free T3 are low-normal, with normal prolactin and no systemic inflammatory disease. What is the most likely unifying process?

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Correct answer: E — Persistent low energy availability causing REDs

The best answer is “Persistent low energy availability causing REDs”. Relative energy deficiency in sport can affect men with a normal BMI and need not involve a formal eating disorder. Persistent low energy availability suppresses reproductive and metabolic axes, impairs bone health and blunts training adaptation, explaining reduced libido, stress injury and falling performance. Primary gonadal failure would typically raise gonadotropins and does not unify bone and performance changes; normal prolactin weakens hyperprolactinaemia, while isolated overtraining should not be assumed before assessing energy availability.

Reference: IOC 2023 consensus statement on REDs: https://pubmed.ncbi.nlm.nih.gov/37752011/