If you're a guy of a certain age, chances are you wouldn't think of hitting the gym without a jockstrap. For the uninitiated, the item known more formally as an "athletic supporter" consists of an elasticized waistband and leg straps connected to a pouch that holds the testicles close to the body. You women can think of it as a sports bra for a guy's balls.

Bike Athletic, the jock's apparent inventor and primary distributor, claims that it has shipped 350 million supporters in the past 130 years. But recently this elasticized chain binding men across the generations has snapped. At my gym, I've been horrified to see young guys lifting weights with boxer shorts peeking from their gym pants. I called Bike to see if my observations reflected a larger truth. "Kids today are not wearing jockstraps," answered spokesperson Jenny Shulman.

The collapse of this age-old bond between fathers and sons might speak elegiac volumes, except for one thing: jocks don't do much. Bike claims the contraption was invented in 1874 as "support for the bicycle jockeys riding the cobblestone streets of Boston." The manly wisdom that has prevailed in locker rooms for more than a century is that wearing an athletic supporter protects you from getting a hernia. The doctors I spoke to told me that's "an old athlete's tale."

"They kind of keep the genitalia from flopping around, is the best I could tell you," says Dr. William O. Roberts, a past president of the American College of Sports Medicine.

Jocks offer no protection against the relatively common inguinal hernia, in which a portion of the gut descends through the canal that contains the spermatic cord. They also won't protect you from what's known as a "sports hernia," a painful tearing or weakness of the muscles or tendons in the pubis area that's also known as "athletic pubalgia." (On the other hand, the jockstrap isn't to blame for my high school bout with jock itch. The itching starts when the warmth and wetness allow the fungus Trichophyton rubrum to flourish. That can happen, jock or no jock.)

Bike's position is that athletic supporters "fight fatigue" and "prevent strain." Indeed, jockstraps do a fine job of holding your balls out of harm's way. But while working out in boxer shorts (or stark naked) isn't a good idea, a decent pair of form-fitting briefs will probably do the job just as well.

The best reason to wear an athletic supporter is so you can wear a protective cup. Jockstraps come in two flavors: plain, and a kind of marsupial version that accepts a removable cup made of hard plastic. A well-placed blow in this region is not only agonizing; it can destroy a testicle.

While most men can get by without athletic supporters, a lot more ought to wear cups. Kids these days have helmets for practically everything; I wouldn't be surprised to see my sons wearing them for violin practice. But surprisingly few wear cups for sports, as I make my sons do for Little League and roller hockey. The young consider cups annoying, which explains why many eschew them even in situations that would seem to call for Kevlar.

I had heard that NFL players don't wear cups but was still astonished when Joe Skiba, assistant equipment manager of the New York Giants, provided confirmation. "The majority of players feel that less is more, especially padding below the torso," he explained. "They feel that it hinders their speed and performance."

Skiba says that many football players now sport a garment called compression shorts. According to Bike, which has diversified its athletic undergarment portfolio in these jock-unfriendly times, these stretchy shorts provide support and "steady, uniform pressure" to hold the groin, hamstring, abdomen, and quadriceps muscles in place during "the twisting, stretching and pivoting action of a game or strenuous exercise." They're also supposed to "fight fatigue by helping prevent vascular pooling."

Dr. Roberts is skeptical. "If the short is compressing enough to prevent pooling of blood, will it not also prevent blood flow from below?" he asks. "Would this flow obstruction not lead to calf fatigue and loss of lower muscle function?" But no matter whether they really "fight fatigue," it's no surprise that compression shorts are eating into the jock's market share. The shorts are more comfortable and less embarrassing-looking.

Still, Bike thinks there's snap in the old supporter yet. The company is launching a line with new fabrics and designs that they say will hit stores next year. They're also set to debut the "Boxer Jock" and the "Brief Jock"products with the support of a jock without the outdated appearance. After all, the Bike athletic supporter hadn't changed in 30 yearsright around the time I started wearing one. Nowadays, I just wear briefs to the gym. All the other stuff is just too much of a stretch.

Daniel Akst is a novelist and essayist living in New York's Hudson Valley.