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Cycling and Chafing Cream Linked to Increased Estrogen levels in Male Cyclists

Tim Boyer's picture
Male Cyclist

A recently published article titled Reproductive Hormones and Interleukin-6 in Serious Leisure Male Athletes in the European Journal of Applied Physiology by researchers from the UCLA School of Nursing tells us that compared to triathletes and recreational athletes, serious cyclists may be facing hormonal imbalances that could have reproductive consequences.


The design of the study was to collect and compare data on the circulating hormone levels detected in male athletes who vary in their level of activity and choice of sport. This research is based on previous studies that have shown that ultra-endurance levels of exercise can affect the reproductive health of some athletes.

In the study, 107 male volunteers between the ages of 18 and 60 were categorized by their personal levels of exercise intensity and sport of choice and divided into three groups consisting of: 16 triathletes, 46 cyclists and 45 recreational athletes.

The participants in the study filled out a questionnaire that assessed their levels of activity and then provided blood samples for analysis. The blood samples were then measured for their levels of a variety of hormones as well as the presence of inflammation biomarkers.

What the blood samples revealed was that serious cyclists have 50% more testosterone in their blood than the recreational athletes and that cyclists also have twice as much estradiol in comparison to the recreational athletes and triathletes studied.

According to a news release by UCLA, the study’s lead author Leah FitzGerald states that, “Plasma estradiol and testosterone levels were significantly elevated in serious leisure male cyclists, a finding not previously reported in any type of male athlete…although preliminary, these findings warrant further investigation to determine if specific types of exercise may be associated with altered sex-hormone levels in men that could affect general health and reproductive well-being," says FitzGerald.

In men, a small percentage of the normal circulating level of testosterone is converted into estradiol—a form of estrogen—which is normal and does not adversely affect a man’s health. However, if too much estradiol is present it can then lead to loss of secondary sex characteristics such as pubic hair and cause the development of enlarged male breasts (gynecomastia).

A second finding of the study that may play a role in an imbalanced hormone level in male cyclists might be linked to the use of some commercial anti-chafing creams generically referred to as “chamois cream.”

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Chamois creams are applied directly to the perineum as a lubricant to prevent saddle sores and to kill off bacteria that thrive in the moist, warm environment of sweaty shorts. The problem, however, is that some creams contain parabens that are estrogen hormone agonists. Parabens are often used as anti-microbial preservatives in a wide range of consumer products, especially in cosmetics. Animal studies have demonstrated weak estrogenic and other endocrine disrupting effects of parabens, including reduced testosterone levels in exposed male rats.

The researchers reported that they did find an association between an increase in estrogen levels and increasing years of chamois cream use - particularly for male cyclists using the cream for more than four years. However, they also note that no direct cause and effect has been found and that additional studies are needed.

For additional information about how cycling can adversely affect a male cyclist’s reproductive health, follow this link to an article on the hazards of bike seats on impotence.

Image Source: Courtesy of Wikipedia


“Reproductive Hormones and Interleukin-6 in Serious Leisure Male Athletes” European Journal of Applied Physiology 2012, DOI: 10.1007/s00421-012-2356-2; Leah Z. FitzGerald et al.

UCLA NewsRoom

This page is updated on May 12, 2013.