The following submission statement was provided by /u/filosoful:

A new study from Harvard Medical School researchers at Brigham and Women’s Hospital suggests that men who regularly lift heavy objects at work have higher sperm counts than men whose work is less physically demanding.

The study, published in Human Reproduction, is part of the Environment and Reproductive Health (EARTH) cohort, a clinical study that aims to explore how environmental chemicals and lifestyle choices affect reproductive health.

Please reply to OP's comment here: https://old.reddit.com/r/Futurology/comments/11dhcoe/physically_demanding_work_tied_to_male_fertility/ja8l1gm/