Feeling hormonal How serious cycling could be playing havoc with male reproductive health
16:27 GMT, 23 May 2012
Male cycling enthusiasts may have more to worry about than saddle sores and road safety, after a study found the sport can play havoc with their fertility.
Researchers at UCLA School of Nursing found serious cyclists – rather than the recreational rider – could experience hormonal imbalances that could affect their reproductive health.
They found keen bikers had more than double the amount of estradiol in their blood compared to triathletes and other sport enthusiasts.
Serious cycling: Could raise estrogen levels in men
Estradiol is a form of estrogen and, in males, is produced as an active metabolic product of testosterone.
Possible conditions associated with elevated estrogen in males include gynecomastia, a condition that may result in the loss of pubic hair and enlarged breast tissue.
Study author assistant professor Leah FitzGerald, said: '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.'
Most research studying the effects of exercise on reproductive health has focused on female athletes; there have been few studies that have looked at male endurance-trained athletes.
The UCLA study explored associations between exercise intensity and circulating levels of reproductive hormones in both serious leisure athletes and recreational athletes.
The researchers divided 107 healthy male study subjects (ages 18 to 60) into three groups: 16 triathletes, 46 cyclists and 45 recreational athletes.
Participants completed the International Physical Assessment Questionnaire to provide an objective estimate of time they spent participating in different levels of physical activity and inactivity during the previous week.
Blood samples were then collected from each participant to measure total testosterone, estradiol, cortisol, interleukin-6 and other hormones.
Plasma estradiol concentrations were more than two times higher in the cyclists than in the triathletes and recreational athletes, and total testosterone levels were about 50 percent higher in cyclists than in the recreational athletes.
'Plasma estradiol and testosterone levels were significantly elevated in serious leisure male cyclists, a finding not previously reported in any type of male athlete,' said Leah FitzGerald.
One of the interesting findings of the study related to the use of chamois cream used by some cyclists to prevent chafing.
In the study, 48.5 percent of cyclists – compared with 10 percent of triathletes – reported using a paraben-containing chamois cream.
At this time, however, no direct cause and effect has been found, the researchers said.
The study has been published in the European Journal of Applied Physiology.