A key to endurance in exercise is oxygen utilization. As you workout, your body uses a lot of oxygen, and depleting that oxygen will (as anyone who has ever been out of breath knows) make you feel tired, sometimes well before your muscles give out. Now a new study suggests that beet juice may be able to increase endurance by 16 percent—more than is possible by any other means, including training. But be careful making use of this news: it's possible to have too much of a good thing.
Researchers at the University of Exeter's School of Sport and Health Sciences tested the effects of beet juice on eight men between 19 and 38 years old. All the men drank half a liter per day of beet juice for six days, and then were asked to cycle on a stationary bike. The men followed the same procedure on a different week, this time using a placebo of black currant juice. The beet juice gave the men the strength to cycle an average of 16 percent longer. And, after the beet juice the men also had a lower resting blood pressure than after the currant juice. Said Professor Andy Jones, an author of the study, "Our study is the first to show that nitrate-rich food can increase exercise endurance. We were amazed by the effects of beet juice on oxygen uptake because these effects cannot be achieved by any other known means, including training." He went on to point out the possible benefits of the research beyond the realm of athletics: "I am sure professional and amateur athletes will be interested in the results of this research. I am also keen to explore the relevance of the findings to those people who suffer from poor fitness and may be able to use dietary supplements to help them go about their daily lives."
The effects of beet root on blood pressure were studied last year, when a study published in the journal Hypertension showed that the same half-liter of beet juice used for the exercise study could lower blood pressure by roughly 10 points—more than the effect of many prescription drugs. (For this study, the beet juice went up against water rather than blackcurrant juice.) Here the effect was very immediate: the beet juice dropped blood pressure within an hour of its consumption, and had its strongest effect two to three hours later.
What is beet juice doing? According to the researchers from both studies, beets are very high in nitrates, which when processed in the body increase our levels of nitric oxide. And nitric oxide, in turn, helps to relax blood vessels, and improve oxygen efficiency. Hence the lowered blood pressure and increased endurance of beet juice drinkers.
Beets are the newest vegetable to study for cardiovascular effects, but they are not alone in being high in nitrates. In particular, lettuce, spinach, and other green, leafy vegetables are also rich in nitrates, and may gloss your initiation to beet juice while giving many of the same benefits. Remember, it is best to enter the world of beet juice with caution. Some people are intolerant of beet juice, and may feel headachey or ill. Some don't appreciate the red urine that may result. And beet juice is seriously strong stuff—it's not easy to drink much of it each day. So it might be best to mix beet juice with other fruit or vegetable juices. Of course, adding spinach juice to cut the flavor of beets may not appeal. In that case, try carrot or apple juice for a mixer. Then get out there and claim your 16 percent increased endurance!