Glucocorticoids accelerate erythropoiesis in healthy humans - should the use in sports be reevaluated?

Purpose: The World Anti-Doping Agency prohibit glucocorticoid administration in-competition but not in periods out-of-competition. Glucocorticoid usage is controversial as it may improve performance, albeit debated. A hitherto undescribed but performance relevant effect of glucocorticoids in healthy humans is accelerated erythropoiesis. We investigated whether a glucocorticoid injection accelerate erythropoiesis, increase total hemoglobin mass, and improve exercise performance.

Methods: In a counterbalanced, randomized, double-blinded, placebo-controlled crossover design (3-months washout), ten well-trained males (peak oxygen uptake: 60 ± 3 mL O₂·min^-1·kg^-1) were injected with 40 mg triamcinolone acetonide (glucocorticoid group) or saline (placebo group) in the gluteal muscles. Venous blood samples collected before and 7-10 h, 1, 3, 7, 14 and 21 days after treatment were analyzed for hemoglobin concentration and reticulocyte percentage. Hemoglobin mass and mean power output in a 450-kcal time trial was measured before as well as one and three weeks after treatment.

Results: A higher reticulocyte percentage was evident three (19 ± 30 %, P < 0.05) and seven (48 ± 38 %, P < 0.001) days after glucocorticoid administration, compared with placebo, whereas hemoglobin concentration was similar between groups. Additionally, hemoglobin mass was higher (P < 0.05) seven (glucocorticoid: 886 ± 104 g, placebo: 872 ± 103 g) and 21 days (glucocorticoid: 879 ± 111 g, placebo: 866 ± 103 g) after glucocorticoid administration compared with placebo. Mean power output was similar between groups seven (glucocorticoid: 278 ± 64 W, placebo: 275 ± 62 W) and 21 days (glucocorticoid: 274 ± 62 W, placebo: 275 ± 60 W) after treatment.

Conclusions: Intramuscular injection of 40 mg triamcinolone acetonide accelerates erythropoiesis and increase hemoglobin mass but does not improve aerobic exercise performance in the present study. The results are important for sport physicians administering glucocorticoids and prompt a reconsideration of glucocorticoid usage in sport.