Last Christmas, my well-meaning wife, knowing I was in need of some good workout pants, picked up a pair for me from Lululemon. The highly-coveted brand, renowned for virtually inventing the booming “athleisure” apparel category, certainly does make a nice pair of stretchy pants. Slim to the hips and snug around the crotch, my new pair felt like a toreador’s pajamas. But given that my pants preference runs more in the direction of MC Hammer than Mick Jagger, I decided they were not quite for me. Frankly, I didn’t think I had the cojones, so to speak, to pull off the look.

Little did I know that Lululemon had not long before rolled out its ABC Pant ($128, lululemon.com), a trouser showcasing the label’s signature slim fit, but built with “ABC (anti-ball crushing) engineering” to give “you and the family jewels room to breathe.”

RELATED: Fitness Finds Under $100

Since then, the ABC pant has helped to drive a 16% increase in same-store sales last quarter in Lululemon’s menswear business, making them one of the most popular items, according to a report from Bloomberg Business. “Given the trend toward slimmer, snugger, lower-rise trousers, they make a certain sort of sense. They offer the best of both worlds: looking slim while avoiding any potential crowding,” says Matthew Kitchen, a men's style writer and associate editor at mensjournal.comof the pants' runaway popularity.

And it turns out there is a very good reason to give your boys some extra room to roam.

RELATED: 12 Signs of Depression in Men

First of all, there is actually some truth to the urban legend-sounding idea that wearing tight clothing can "cook your balls" and affect fertility. "If you subject men to prolonged exposure to increased temperature in the testicles, it will have a negative effect on the production of sperm, and low blood flow in the area can have a similar impact,” explains Joshua U. Klein, MD, Medical Director of Reproductive Medicine Associates, a fertility clinic in Brooklyn, New York.

And even though the research on tight clothing's contribution to the problem is mixed, “given the potential problem, it makes sense for a man who’s having trouble getting [his partner] pregnant or has poor sperm quality to find pants that allow for a little breathing room,” Dr. Klein says.

Plus, like the ubiquitous yoga pant and other athleisure staples for women, the ABC pant is meant to be worn to the biergarten and to the gym. So if the added convenience of already being in workout clothes is enough to motivate you to get to the gym or head outdoors, all the better. Adds Dr. Klein: “What we do know is that men who sit all day are more likely to have poorer sperm quality, and that exercise in general is associated with better sperm quality.”

That, and better heart health, lower stress levels, and a hardier immune system.

RELATED: 13 Surprising Facts About Testosterone