A new study suggests that men in occupations that require physical exertion may be more fertile than white-collar workers sitting at desks.
The study published in the journal Human Reproduction in February looked at 950 semen samples from 377 male partners in couples seeking fertility treatment between 2005 and 2019.
The men had a median age of 36 and were mostly white. They completed a questionnaire on how often they lifted or moved heavy objects, their physical exertion at work, and their typical shift schedule. Blood samples were also analysed.
Among the participants, men who reported often lifting or moving heavy objects at work had a 46% higher sperm concentration and 44% greater total sperm count than men who reported never lifting or moving heavy while on the job. They also had higher levels of testosterone, the hormone that regulates sperm production as well as muscle mass and libido.
The researchers adjusted for other possible factors for the disparity, including age, body mass index (BMI), education, race, and smoking.
“Men working non-daytime/rotating shifts and those with physically demanding jobs have higher sperm concentration and total sperm count as well as higher estradiol and total testosterone concentrations,” the researchers summarised their findings.
They also reported that while research on male fertility has focused on environmental, dietary, and lifestyle factors, “little attention has been paid to occupational factors.”
It shows that the trend of fewer men getting university degrees, which often lead to 9-to-5 desk jobs, may have a positive aspect.
At the same time, the study authors noted that the participants were all men who were seeking fertility treatment and that men who were less healthy may not be able to engage in physically demanding work, limiting the study’s application for drawing conclusions about the general population.
Nevertheless, the findings of the study coincide with the body of research that has shown a positive link between physical activity and healthy sperm. A healthy body has the most favourable conditions for generating healthy sperm and exercise is a key factor in health.
“Whatever your doctor tells you to do to help you care for your heart is going to help your fertility,” Shanna Swan, a leading reproductive epidemiologist and professor at the Icahn School of Medicine at Mount Sinai, told Euronews.
It provides one more piece of evidence that sitting is the new smoking.
