Looking to muscle up? Forget the powders and potions -- stock up on beet juice. That's the conclusion of a study that finds the high nitrate content in beets and spinach will make you stronger.
Of course, Popeye knew that years ago, but the fictional character thought it was the iron in spinach that did the trick. Nope, it's the nitrate, say researchers at Washington University School of Medicine in St. Louis. Celery, arugula, and other leafy greens are also rich in the nutrient.
Building on a growing body of work that suggests dietary nitrate improves muscle performance in many elite athletes, the WUSL researchers found that drinking concentrated beet juice -- also high in nitrates -- increases muscle power in patients with heart failure.
"It's a small study, but we see robust changes in muscle power about two hours after patients drink the beet juice," said senior author Linda R. Peterson, MD, associate professor of medicine. "A lot of the activities of daily living are power-based -- getting out of a chair, lifting groceries, climbing stairs. And they have a major impact on quality of life.
"We want to help make people more powerful because power is such an important predictor of how well people do, whether they have heart failure, cancer or other conditions. In general, physically more powerful people live longer," Peterson said.
Noted in cyclists
In the September issue of the journal Circulation: Heart Failure, the scientists reported data from nine patients with heart failure. Two hours after the treatment, patients demonstrated a 13 percent increase in power in muscles that extend the knee.Based on research in elite athletes, especially cyclists who use beet juice to boost performance, the study's corresponding author, Andrew R. Coggan, PhD, assistant professor of radiology, suggested trying the same strategy in patients with heart failure.
The researchers observed the most substantial benefit when the muscles moved at the highest velocities. The increase in muscle performance was significant in quick, power-based actions, but researchers saw no improvements in performance during longer tests that measure muscle fatigue.
The researchers pointed out that participants experienced no major side effects from the beet juice, including no increase in heart rates or drops in blood pressure, which is important in patients with heart failure.
While the trial was not designed to find out whether patients noticed an improved ability to function in daily life, the researchers estimated the size of the benefit by comparing the improvement in muscle power with what is seen from an exercise program.
"I have compared the beet-juice effect to Popeye eating his spinach," said Coggan, who specializes in exercise physiology. "The magnitude of this improvement is comparable to that seen in heart failure patients who have done two to three months of resistance training."
The nitrates in beet juice, spinach, and other leafy green vegetables such as arugula and celery are processed by the body into nitric oxide, which is known to relax blood vessels and have other beneficial effects on metabolism.
With the growing evidence of a positive effect from dietary nitrates in healthy people, elite athletes, and now heart failure patients, the researchers also are interested in studying dietary nitrates in elderly populations.
"One problem in aging is the muscles get weaker, slower and less powerful," Coggan said. "Beyond a certain age, people lose about 1 percent per year of their muscle function. If we can boost muscle power like we did in this study, that could provide a significant benefit to older individuals."