There's a secret source of power within you called nitric oxide —and though your body makes it naturally, chances are you need more

Nope, it's not the stuff you inhale at the dentist's office (that's nitrous oxide). Nitric oxide (NO) is produced in your body, and it has far-reaching perks. Your immune cells release it to kill infectious bacteria. It also keeps your mitochondria, which supply you with energy, running smoothly and dilates your blood vessels, reducing blood pressure and improving circulation.

But NO's biggest benefits are reserved for your muscles. "Several recent studies have revealed that the gas makes your muscles more efficient, and as a result they require less oxygen to work out at higher intensities," says Andrew Jones, Ph.D., a professor of applied physiology at the University of Exeter in England. That means it's easier for you to push yourself harder.

Unfortunately, your levels of this beneficial gas start to dip as early as age 25. But it's so essential to good health that Jones says everyone would benefit from upping their supply, including fit women. These three science-backed strategies will help you fill your tank.

Nitric Oxide Cardio

Kick It Higher with Cardio

"When you work out, your heart pumps harder. The additional pressure on the arterial wall triggers the production of NO, which then helps the blood vessels dilate to allow for the increased circulation," says James Rippe, M.D., a preventive cardiologist and fitness expert and the founder of the Rippe Lifestyle Institute, a health research organization. The best exercise for NO production is cardio, because it really revs your heart rate and blood flow, he says. Your levels of the gas will start to climb after a single 30-minute session (like this 30-minute cardio abs workout), but if you continue to get your heart pumping three or more times a week, your body will produce more NO every day.

Nitric Oxide Beet Juice

Get Juiced

While exercising increases your overall stores of NO, you can get a quick jolt of it to help fuel your next workout by downing a glass of beet juice. The drink is loaded with nitrate, a compound the body breaks down to form NO. In a recent study, cyclists who drank five to nine ounces of beet juice two and a half hours before a workout were able to increase the time they spent pedaling by as much as 14 percent. (That's not the only reason endurance athletes swear by beet juice.) Not a fan of beets? Jones says a cup of spinach also has enough nitrate to give you an edge. (Better yet, try a smoothie bowl that hides the taste of beets with berries.)

Nitric Oxide Sun

Step Into the Light

Spending time outdoors will rev up your NO. People who were exposed to UVA rays for 20 minutes found that their NO levels rose and their blood pressure dropped, the Journal of Investigative Dermatology reports. (If that doesn't do it, these other benefits of sunlight will convince you to get outside, stat.) The study authors say the skin has its own stores of NO and that UVA rays unlock them, releasing the molecules into your bloodstream. But this is the same type of UV light that's responsible for skin aging, wrinkles, and cancer, so always put on SPF before heading out. (These sweat-tested sunscreens are great for outdoor workouts.) It will reduce UVA exposure and may mean you produce slightly less NO, but experts say that you'll likely still get enough to reap the health benefits.