A new study by researchers at Brigham and Women’s Hospital, a founding member of the Mass General Brigham Health System, suggests that men who regularly lift heavy objects at work have higher sperm counts. The study, published in human reproductionis part of the EARTH (Environment and Reproductive Health) cohort, a clinical study that aims to explore how exposure to environmental chemicals and lifestyle choices affect reproductive health.
“We already know that exercise is associated with multiple health benefits in men, including those seen on reproductive health, but few studies have examined how occupational factors may contribute to these benefits,” said said first author Lidia Mínguez-Alarcón, reproductive epidemiologist at Brigham’s Channing Division of Network Medicine and co-investigator of the EARTH study. “What these new findings suggest is that physical activity during labor may also be associated with a significant improvement in male reproductive potential.”
Infertility is a growing problem, and it can be caused by a wide variety of complex factors. However, about 40% of infertility cases can be attributed to male factors, such as sperm count, sperm quality, and sexual function. In particular, sperm count and sperm quality are believed to be the main drivers behind the growth in male infertility rates. % between 2000 and 2017.
“Furthermore, there is growing evidence that male infertility is associated with common chronic conditions such as cardiovascular disease and autoimmune disease, underscoring the broader importance of male reproductive health,” said said Mínguez-Alarcón.
The EARTH Study is a collaboration between the Harvard T. Chan School of Public Health and Mass General Brigham to assess the effect of environmental and lifestyle factors on fertility. EARTH collected sample and survey data from more than 1,500 men and women, and the current study focused on a subset of these participants, including 377 male partners of couples seeking treatment in a fertility center.
Researchers found that men who reported often lifting or moving heavy objects at work had 46% higher sperm concentration and 44% higher total sperm count than those who had less physical jobs. Men who reported more physical activity at work also had higher levels of testosterone, a male sex hormone, and unexpectedly higher levels of estrogen, a female hormone.
“Contrary to what some people remember from biology class, ‘male’ and ‘female’ hormones are found in both sexes, but in different amounts,” Mínguez-Alarcón said. “In this case, we hypothesize that excess testosterone is converted to estrogen, which is a known way for the body to maintain normal levels of both hormones.”
While the current study found a relationship between physical activity and fertility in men seeking fertility treatment, further research is needed to confirm whether these findings hold true for men in the general population. The researchers also hope that future studies will reveal the underlying biological mechanisms at play.
“Reproductive health is important on its own, but growing evidence suggests that male infertility can give us insight into broader public health issues, including the most common chronic diseases,” Mínguez-Alarcón said. . “Discovering concrete steps people can take to improve their fertility benefits us all, not just couples trying to conceive. »