Men Who Wear Boxer Shorts Have Higher Quality Sperm, Study Finds

In the case of boxers v. briefs, it's time to let 'em hang loose.

Listen up, lads.

The debate around men's underwear is officially more than just a matter of comfort, as new research reveals men who wear boxer shorts have higher sperm concentrations than men who wear tighter fitting jocks.

A team of Harvard researchers discovered loose is best when it comes to packaging one's package by undertaking the largest study on the issue to-date.

Published this week in Human Reproduction, the study recruited 656 male partners of couples who were seeking infertility treatment between 2000 and 2017. The men were aged between 18 and 56, had an average BMI of 26 and had not had vasectomies.

After providing a semen sample and a blood sample, the group answered a questionnaire to determine which style of underwear they wore most frequently in the previous three months.

Boys in boxers had a 25 percent higher sperm concentration, a 17 percent higher total sperm count and 33 percent more swimming sperm in a single ejaculation than their tightie whitie-wearing counterparts.

Harvard researchers undertook the largest study of its kind to determine if wearing tight underwear impacts men's semen quality. Image: Getty

While this investigation is the largest that's been done on the issue, scientists have been testing the effects of underwear choices on a man's swimmers for decades.

A study published in 1990 followed two men for an entire year as they alternated between tight fitting bikini type briefs to loose fitting boxer briefs in three-month episodes. Results revealed “sperm density, total number of sperm, total number of motile sperm, and total number of motile sperm per hour of abstinence,” gradually increased under loose conditions, and decreased under tight ones.

A more recent study however, conducted by the National Institutes of Health, looked at 35 aspects of sperm quality for 500 men and determined while some aspects were both better or worse between wearers of tight and loose fitting styles, none of the results were statistically significant.

Underwear choice also didn't affect how long it took for participants to get their partners pregnant.

Researchers discovered tighter underwear styles including briefs, bikinis (very brief briefs) and jockeys lead to lower sperm concentration. Image: Getty

But as lead researcher Dr. Lidia Mínguez-Alarcón points out, this new study yielded not only statistically significant results, but also revealed men who most frequently wore boxers had lower levels of follicle-stimulating hormone (FSH) compared to those who wore tighter-fitting briefs.

FSH stimulates sperm production, which leads researchers to believe the hormone begins to work when it needs to compensate for testicular damage caused by increased scrotal temperatures and decreasing sperm counts and concentration.

Mínguez-Alarcón said while this hypothesis will need confirmation with further research, this understanding of the link between underwear choice and indicators of testicular function was missing in previous studies.

“Since men can modify the type of underwear they choose to wear, these results may be useful to improve men’s testicular function," she said.