VanHeest, J. L., Mahoney, C. E., Cappaert, J. M., Hill, K. W., De Souza, M. J., & Rodgers, C. D. (2003). Induction of low T3 syndrome in female swimmers during a competitive season. Medicine and Science in Sports and Exercise, 35(5), Supplement abstract 1829.

Sub-elite female swimmers (N = 10) were assessed for thyroid stress every other week during a 12-week training period. The group was divided into an improved (N = 5) or non-improved (N = 5) group based on end of season performances.

Free T3 and Free T4 were significantly lower in the non-improved group than in the improved group at all times across the observation period. Poor performing female swimmers showed signs of low T3 syndrome (abnormalities in thyroid hormone and thyroid-stimulating hormone levels), which might reflect an altered metabolic state.

Implication. Poorly performing female swimmers might be suffering from thyroid mediated problems.

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