Males with manual careers that lift heavy objects are 44% more likely to have a higher sperm count than those with less physically demanding jobs, a new study reveals.
Latest research conducted by Harvard TH Chan School of Public Health and Mass General Brigham has found that sperm count is higher amongst men who have jobs that require heavy lifting.
More than 370 men undergoing fertility treatment were analysed during the investigative study.
Each participant filled in a survey to outline their standard work routines and whether or not their job included carrying heavy objects.
The results state: “Men who reported often lifting or moving heavy objects at work had 46% higher sperm concentrations and 44% higher total counts compared with men who reported never lifting or moving heavy objects at work.”
According to the findings, testosterone was 24% higher in men who work night shifts compared to those only working in the day.
In addition, oestrogen concentrations were 45% higher in men working during the night compared to those who only work during the day.
Chief author Lidia Mínguez-Alarcón said: “Contrary to what some people remember from biology class, ‘male’ and ‘female’ hormones are found in both sexes, but in different amounts.
“In this case, we hypothesise that excess testosterone is being converted into oestrogen, which is a known way for the body to keep normal levels of both hormones.”
These new findings slam previous studies that have said that: “Work-related heavy exertion was related to lower sperm concentration and total sperm count, and shift work was not associated with semen quality.”
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Mínguez-Alarcón noted: “We found that work schedules and physically demanding jobs are associated with improvements in several markers of testicular function among men attending a fertility centre.
“There is increasing evidence that male infertility is associated with common chronic diseases such as cardiovascular disease and autoimmune disease, highlighting the broader importance of male reproductive health.”
She added: “Uncovering actionable steps people can take to improve their fertility stands to benefit all of us, not just couples trying to conceive.”
The full study has been published in the journal Human Reproduction.
