A study of 377 men who had partners seeking treatment at a fertility clinic in Boston, Massachusetts, has shown that men who lift heavy weights frequently as part of their job, have higher sperm concentration and count.
Results published in the journal Human Reproduction showed men who reported lifting or moving heavy objects at work had 46 percent higher sperm concentrations and 44 percent higher sperm counts than men who had more sedentary jobs. These men were found to have higher concentrations of the hormones testosterone and oestradiol too.
'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,' said first author Dr Lidia Mínguez-Alarcón, a reproductive epidemiologist in Brigham's Channing Division of Network Medicine and co-investigator of the study.
