|Image 1: There are two types of endurance exercise - the one that is healthy for obese diabetics and the one that chronically stresses and, in the worst case, eventually kills healthy but overambitious hobby athletes; the photo shows a collapsed runner at the 2007 London Marathon, where 22 of his comrades died |
In their study, Clemens Kirschbaum et al. analyzed the hair samples of 304 amateur endurance athletes (long-distance runners, triathletes and cyclists; 190 females, 114 males, mean age ~38 years) and 70 active control subjects (all recruited at local sport events or from friends and family of the authors ;-) and found on average +42% higher hair cortisol concentrations in the endurance athletes.
|Figure 1: Relative increase in hair cortisol levels in endurance athletes compared to controls (Kirschbaum. 2011)|
|Figure 2: Relative increase in hair cortisol levels of endurance runners in relation to average weekly training load in kilometers (calculation based on a regression with r=0.32, indicating a below average precision; Kirschbaum. 2011))|
that repeated physical stress of intensive training and competitive races among endurance athletes is associated with elevated cortisol exposure over prolonged periods of time.Even more important is their advice that, due to the possibly important implications of these findings, it would be necessary to study potentially detrimental effects on the somatic and mental health of the athletes in the future! Well, I probably don't have to tell you that the SuppVersity is going to be the place, where you will read about those studies first ;-)