Study leader Professor Andy Jones said: “Our study is the first to show that nitrate-rich food can increase exercise endurance. We were amazed by the effects of beetroot juice on oxygen uptake because these effects cannot be achieved by any other known means, including training.”
In addition to endurance athletes, the research team believes drinking beetroot juice could also benefit elderly people or those with cardiovascular, respiratory or metabolic diseases. “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,” said Jones.
Beetroot juice doubled the amount of nitrate in volunteers’ blood and reduced the rate at which muscles used their main source of energy.
It also helped muscles work more efficiently and lowered their oxygen uptake during both low-intensity and high-intensity exercise.
The research was conducted with eight men aged between 19 and 38. Each drank 500ml per day of organic beetroot juice for six consecutive days before completing exercise tests including cycling and exercise bike performance.
They also received a placebo of blackcurrant cordial for six consecutive days before completing the same tests.
After drinking beetroot juice, the men were able to cycle for an average of 11.25 minutes - 92 seconds longer than after drinking the placebo. “This would translate into an approximate 2% reduction in the time taken to cover a set distance,” said the researchers. “The group that had consumed the beetroot juice also had lower resting blood pressure.”
Although unsure precisely how the nitrate in the beetroot juice boosts stamina, they believe it could result from the nitrate turning into nitric oxide in the body. That, in turn, reduces the oxygen cost of exercise.
Scientists at Exeter University worked in partnership with Peninsula Medical School to conduct the research the results of which were published in the Journal of Applied Physiology.
The team plans to conduct more research to better understand the relationship between nitrate-rich foods and exercise physiology.
Meanwhile, last year, beetroot juice was shown to cut blood pressure in research conducted by the Peninsula Medical School, Barts and the London School of Medicine. Research results were published in February 2008 in the American Heart Association journal Hypertension.
Source: Journal of Applied Physiology.
Title: Dietary nitrate supplementation enhances muscle contractile efficiency during knee-extensor exercise in humans.
Authors: Stephen Bailey, Jonathan Fulford, Anni Vanhatalo, Paul Winyard, Jamie Blackwell, Fred DiMenna, Daryl Wilkerson, Nigel Benjamin, and Andrew M. Jones.