For most athletes, a mouth guard is simply a piece of protection, something to be tolerated to avoid a worst-case scenario. But two new products are changing the way players view mouth guards and at the same time are broadening their appeal to competitors in other sports. Weekend warriors to elite athletes are putting down hundreds or even thousands of dollars to purchase mouthpieces that promise not only to protect but to improve their performance.

The products, the Makkar PPM and Under Armour Performance Mouthwear, work by shifting the jaw into a more comfortable position. The manufacturers claim that the shift helps to relax the entire body — improving posture, range of motion, flexibility, balance and strength.

The mouthpiece works by preventing the body’s natural stress response, according to Dr. William Balanoff, a dentist in Fort Lauderdale, Fla., employed by Bite Tech, the company that developed the Under Armour product. When we are under stress, he said, we clench our teeth, completing a circuit that leads to the release of stress hormones into the bloodstream as part of the fight or flight response. While those hormones can have short-term benefits, such as increased strength or reaction time, over time the detriments exceed the gains. Performance mouthpieces aim to short-circuit the process by preventing the teeth from clenching.

“When people keep their teeth separated, they’re a little stronger,” said Dr. Vincent Quas at the Bend Orthodontic Center, one of the local dental practices that offers the Under Armour product. “But the problem is you can’t do that in the middle of competition.”

In the heat of competition, athletes naturally clamp down. Quas said researchers have been looking at the link between mouthpieces and performance for more than 30 years, but the devices have never gained widespread acceptance.

“It’s not new, but what they’ve done is a marvelous job of marketing,” he said. “And they’ve developed a material that is superior to anything we’ve had before.”

Dr. Kelley Mingus, at Distinctive Dentistry at Broken Top in Bend, has been selling the Makkar product for about 18 months.

“It’s more than just a shock-absorber or a cushion,” he said. “You’re encouraging your body to be in proper postural alignment, which will help you resist injury.”

Mingus said the mouthpiece also positions the jaw in more of an underbite position, which helps to open up the airway. “From an endurance athlete perspective, you’re going to have an increased airflow, more oxygen in the lungs and less lactic acid buildup,” he said.

That could help runners and cyclists train harder and longer before tiring and, in theory, improve performance on race day.

Do the mouth guards work? There’s plenty of anecdotal evidence. More than half of the New Orleans Saints football team that played in the Super Bowl on Sunday wear the PPM mouth guards. So do alpine skier Bode Miller and pro golfer Scott McCarron. Meanwhile, Under Armour and Bite Tech have signed pro athletes, including football star Adrian Peterson and hockey great Brett Hull, as investors and pitch-men.

And there’s some research to suggest the performance claims are more than just marketing.

With funding from Makkar, researchers at Rutgers University tested the effect of the PPM in 22 male professional and college athletes. They found the mouthpiece significantly improved their performance in vertical jumps and a strength test but did not impact the number of repetitions they could do on the bench press.

Bite Tech funded research at The Citadel in South Carolina that tested how the mouthpiece affected endurance activities. The researchers found that lactate levels in the blood were 18 percent lower with the mouthpiece than without. The higher the lactate levels, the quicker the muscle will tire. CT scans also revealed that the athletes’ airways were open wider when they used the mouthpiece.

The mouthpieces are slowly starting to gain appeal among competitive athletes but are just now starting to filter into the mainstream market.

“The big barrier is cost,” Mingus said. “That’s where the benefit of Under Armour comes in. Under Armour allows you to get mass exposure, so the cost is going to come down.”

Mingus sells three different PPM products — from an entry-level product for about $500 to a high-end custom model that runs more than $2,000. The difference is mainly in the techniques used to determine the ideal jaw positioning. The most expensive model involves a two-hour process using computers and electrodes to find the sweet spot.

The Under Armour mouthpieces range in price from $300 to $500, and Quas said he doesn’t believe there’s additional value in paying for the more expensive Makkar product and the fitting process.

“I think it’s just craziness,” he said. “PPM is exactly the same; there’s no difference.”

Mingus has sold “about 8 to 10” of the PPM products, mostly to high school students playing football or baseball or participating in wrestling.

“I think the biggest sport that’s going to have a benefit is golfing,” he said. “Increased range of motion, flexibility and balance will give you a more consistent ball-striking ability and you have an increased power stroke. This is going to be really good for the aging golfer.”

Mouthpieces would be a new development in the golf world, although several professional golfers now use them. James Chrisman, an insurance agent from Bend and a former University of Oregon golfer, purchased the entry-level PPM product from Mingus late last year. He had a chance to use the mouth guard for the first time while golfing in Phoenix this winter and noticed an immediate impact.

“I hadn’t played for a month, and I hit it great,” he said. “So it was, ‘Gosh, maybe this thing does work.’”

Chrisman said he hasn’t played enough with the mouthpiece yet to give a firm pronouncement on the product’s effectiveness, but he’s definitely intrigued. He used it mainly during practice at the driving range, but he’s noticed that he’s hitting the ball farther with his driver and irons. Is that better range of motion and flexibility, or is it all in his mind?

“Golf is all in your skull,” he said. “If it makes you think you’re doing better, then use it.”