Men who do manual labor may have healthier sperm than their bosses
A study from Harvard University found that workers who regularly lift weights or move heavy objects had almost 50 percent more sperm than those who sit down.
They also had higher levels of testosterone, the male sex hormone that regulates libido as well as muscle mass and sperm production.
Worldwide sperm counts are believed to have halved over the past five decades, with scientists blaming a range of environmental, dietary and lifestyle factors.
"We already know that exercise is associated with numerous health benefits in humans, including those observed in reproductive health, but few studies have looked at how occupational factors may contribute to these benefits," said the study's first author, Lidia Mínguez. - Alarcón.
"What these new findings suggest is that physical activity during work may also be associated with significant improvement in male reproductive potential," she said in a statement.
The researchers examined 950 samples from 377 men.
The men - who had an average age of 36 - completed a questionnaire about how often they lifted or moved heavy objects and their level of physical exertion at work.
Among participants, 12 percent reported frequently lifting or moving heavy objects at work. These men had a 46 percent higher sperm concentration compared to men who reported never lifting or moving heavy objects at work.