|Image 1: Norman Stadler 2004 winner of the Ironman Hawaii probably had a hell of a testosterone boost, when this photo was taken (img. Kai Baumgartner. 2004)|
What's worse? Cycling, or swimming, cycling and running?
To test the hypothesis that "serious leisure time athletes", in this case cyclists (>8h of intense training per week) and triathletes (>5h of intense training per week), are at much greater risk of developing training-related hormonal disturbances than the average "recreational athlete" who performs less than 3.5h of moderate exercise per week, L.Z. Fitzgerald and his colleagues from the School of Nursing at UCLA assessed the body composition, physical activity and hormonal and inflammatory markers of 107 healthy men (age 18-60 years).
|Figure 1: Demographic and physical variables of the cyclists (n=46), triathletes (n=16) and recreational athletes (n=45) of which I believe that they me independent (caffeine, age) and dependent (body fat, lean body mass) confounding factors data expressed relative to the statistical average; calculated based on Fitzgerald. 2012|
|Figure 2: Estradiol, testosterone, SHBG, luteinizing hormone (LH) and follicle stimulating hormone (FSH) expressed relative to data from a reference cohort I "borrowed" from Brambilla et al. (2009); calculation based on Fitzgerald. 2012|
If you cherish your manhood, man up and don't use chamois cream
A closer analysis of the individual hormone levels does yet reveal a pretty awkward phenomenon: In spite of having the lowest luteinizing hormone levels of all three groups (-56% below "my" reference, i.e. Brambilla. 2009) and an exorbitant amount of estrogen (+113% more than "my" reference) they also have the highest amount of testosterone in their blood. And while I am usually smart-assing scientists for following mainstream paradigms and not following up interesting / surprising results, this is one of the rare cases, where I really have to take my hat off to Mr. Fitzgerald and his colleagues, because I would never have thought of the somewhat shocking explanation the guys came up with:
Some cyclists apply chamois cream to their perineum area to help prevent chafing and bacterial infections related to bicycle saddle sores. The various commercial creams contain a variety of ingredients including lubricants, polymers, oils (jojoba, lanolin, mineral, olive, peppermint, rosewood, soybean, tea tree, St John’s wort), vitamins (A, C, D, E), and alcohols. Additionally, some of these creams contain parabens which are anti-microbial preservatives, but also weak estrogen agonists (Frederiksenet. 2011). In vitro studies demonstrate that parabens bind to estrogen receptors and initiate estrogenic cellular path-ways (Darbre. 2004).And in fact, a follow up questionnaire confirmed the scientists' suspicion. While only 10% of the triathletes, who obviously cycle as well, used paraben-containing chamois cream roughly 50% of the cyclists applied them regularly to their best parts - with shocking side-effects:
Among the cyclists, there was a significant dose-dependent increase in estradiol levels with increasing years of chamois cream use for men using the cream for more than 4 years (p = 0.03) with notable effect size (partial n² =0.12).If we briefly discard the high estrogen levels in the cyclists and take an objective look at what conventional wisdom tells us about the detrimental effects of high intensity endurance exercise in general and the arduous combination of swimming, cycling and running, also known as triathlon, this study does still provide enough evidence to cause another of our broscientific myths to totter...
...high intensity endurance exercise does not per se reduce testosterone levels!
|Image 2: I wonder if there is a "don't use if you don't want to castrate yourself" warning anywhere on this tub of chamois crème.|