The Effect of an Ultradistance Foot Race on Thyroid, Stress Hormone Levels and the Immune System

Abstract

Background: The aim of the present research is to investigate the effect of an ultra-marathon race on the levels of thyroid, immune and stress system hormones. Moreover, to explore a potential correlation of the above-mentioned hormones with stress hormones. Methodology: 30 out of the 40 participants who took part in the race, finished the 246 km in less than 36 hours, and were included in the study. There were 3 different sampling times: prior, after and 48 hours after the race. Blood samples were taken to identify stress and inflammation markers, such as CRP, IL-6 NTproBNP, MBL, troponin, leptin, cortisole and thyroid hormones. Results: CRP, IL-6, SAA, NTproBNP and cortisol showed a dramatic increase after the race, much higher than their initial values, but returned to their initial equilibrium after 48 hours, except SAA which increased further. The behavior of mannose binding lectin with a similar growth trend was similar. Small fluctuations in all the thyroid hormones were observed with initially an increase in the levels, then a downward trend, reaching the initial values again. The only case where the concentration decreased after the race is that of leptin, while troponin concentrations were not detectable. Conclusions: An ultra marathon can be a very stressful event for the body, often elevating hormone levels beyond their normal rate. A significant correlation was observed in the way cortisol changes with CRP, IL-6 and NTroBNP, which reveals the close relationship of the endocrineimmune system in extreme cases of exercise such as that of Spartathlon.