The impact of an ultramarathon on hormonal and biochemical parameters in men.

OBJECTIVE: To examine circulating hormonal responses in men competing in the Western States Endurance Run (WSER, June 23 to 24, 2012): a 161-km trail run that starts in Squaw Valley, CA, and concludes in Auburn, CA. METHODS: We examined 12 men who completed the WSER. Blood samples were obtained the morning before the race, immediately postrace (IP), and 1 (D1) and 2 (D2) days after the conclusion of the WSER. The hypothalamic-pituitary-testicular (HPT) axis was assessed by measuring testosterone and luteinizing hormone (LH). We also examined sex hormone-binding globulin (SHBG) and cortisol. Biochemical and muscle damage markers were also measured. RESULTS: Relative to prerace, there were significant (P ≤ .05) decreases in testosterone, LH, and SHBG, whereas cortisol showed a significantly marked elevation at IP. Testosterone, LH, SHBG, and cortisol remained significantly different from prerace at D1. Additionally, the testosterone to cortisol (T:C) ratio, a marker of anabolism, was decreased at IP and D1. Serum total protein, albumin, and globulin significantly decreased at IP, and remained decreased at D1 and D2. Bilirubin increased significantly IP and D1, whereas alkaline phosphatase decreased at D1 and D2. Creatine kinase, myoglobin, aspartate aminotransferase, and alanine aminotransferase increased at IP, and continued to be significantly elevated at D1 and D2. CONCLUSIONS: Training for and completing the WSER produced a significant suppression in the HPT axis as seen by decreased levels of testosterone and LH. Additionally, running the WSER continued to influence endocrine function until 2 days after the race. Furthermore, the stress caused by the WSER produced severe muscle damage.