In a study at the University of Exeter in England, cyclists who consumed up to half a liter of beet juice daily for six days completed workouts faster than those who didn't drink it, and it took them longer to reach fatigue. "Beet juice contains nitrates that your body converts into nitric oxide, which expands your blood vessels and can lead to more oxygen being delivered to your muscles as you exercise," explains Stella Lucia Volpe, PhD, chair of the department of nutrition sciences at Drexel University in Philadelphia. "This can make it easier for you to go faster and harder for greater amounts of time."
For the best results, drink about 8 ounces (80 calories) on mornings when you have a big sweat session planned. Not a fan of the earthy beverage? Sip smaller amounts throughout the day, or add a splash of lemonade or carrot or orange juice to help cut the flavor. "Just make sure that the beet juice is still the highest concentration—about 90 percent of your drink," Volpe says.
(Please note: Consuming a lot of beet juice could turn your pee and/or poop reddish, so don't freak out if that happens—it's totally normal!) Beets are also high in health-boosting antioxidants, potassium, folate and manganese, and drinking the juice may help lower blood pressure.