Longitudinal Changes in Competitive Performance in Elite 46,XY DSD Runners During Prolonged Testosterone Suppression

Purpose: To assess longitudinal changes in official competitive performance in elite runners with androgen-sensitive 46,XY differences of sex development (DSD) during prolonged testosterone suppression. Methods: This retrospective longitudinal study analyzed nine elite 46,XY DSD runners with type II 5α-reductase deficiency who maintained serum testosterone below 2.5 nmol/L after gonadectomy, gonadotropin-releasing hormone agonist treatment, or combined oral contraceptive use. Outdoor performances in sprint, middle-distance, and long-distance events were evaluated. Semester-best performances were compared with pre-suppression personal bests and expressed as percentage change and World Athletics World Ranking points. Results: Before treatment, mean serum testosterone was 22.5 ± 6.5 nmol/L. Follow-up included 16 performance profiles and 44 semester-best observations over 0–1258 days of suppression. Competitive performance declined after testosterone suppression, with mean decrements of 6.0%, 7.1%, 6.5%, 7.2%, 6.6%, and 4.4% across successive semesters. Across the full observation period, the mean performance decrement was 6.5 ± 3.6%, and after two years it remained approximately 6.0 ± 4.5%. No significant difference in percentage decrement was observed between sprint and middle-/long-distance groups, although substantial interindividual variability was present. Conclusion: Sustained testosterone suppression in elite androgen-sensitive 46,XY DSD runners was associated with a clear but heterogeneous reduction in competitive performance. In several athletes, the decrement remained smaller than the expected elite male–female performance gap, suggesting that prior male-range androgen exposure may confer advantages not uniformly abolished by current testosterone suppression.