The study reveals that drinking beetroot juice reduces oxygen uptake to an extent that cannot be achieved by any other known means, including training.
To reach the conclusion, research team conducted their study with eight men aged between 19 and 38. They were given 500ml per day of organic beetroot juice for six consecutive days before completing a series of tests, involving cycling on an exercise bike. On another occasion, they were given a placebo of blackcurrant cordial for six consecutive days before completing the same cycling tests.
After drinking beetroot juice the group was able to cycle for an average of 11.25 minutes, which is 92 seconds longer than when they were given the placebo. This would translate into an approximate 2 percent reduction in the time taken to cover a set distance. The group that had consumed the beetroot juice also had lower resting blood pressure.
The researchers are not yet sure of the exact mechanism that causes the nitrate in the beetroot juice to boost stamina. However, they suspect it could be a result of the nitrate turning into nitric oxide in the body, reducing the oxygen cost of exercise.
A regular beetroot drink allows you to exercise for longer without tiring
Forget punishing gym workouts and jogging miles uphill.
The key to boosting stamina could be as simple as a glass of beetroot juice.
A daily dose apparently allows us to exercise for longer before tiring.
Just under a pint of beetroot juice a day also lowers blood pressure, boosting heart health.
With some of the benefits even surpassing those gained from the strict training routines followed by professional sportsmen, the researchers admit to being stunned by the results.
And they say that while the earthy tang of the juice might not be to everyone’s taste, it could have a big impact on everyone from athletes training for big events to pensioners who lack the energy to walk to the shops.
The researchers, from the University of Exeter and the Peninsula Medical School, in the same city, recruited eight healthy young men to complete a series of cycling tests.
They took them twice – after drinking beetroot juice once a day for six days and after drinking blackcurrant cordial.
When tasked with cycling at an easy pace, the men used less oxygen after drinking beetroot juice, the Journal of Applied Physiology reports.
This indicates that their muscles were able to do the same amount of work while spending less energy. When they were asked to cycle for as long as they could before stopping, the beetroot juice allowed them to pedal an extra minute-and-a-half before running out of energy.
This 16 per cent increase in endurance means that someone who normally runs out of steam after jogging for hour would be able to keep going for an extra ten minutes.
Alternatively, they could cover the same distance but more quickly.
Researcher Andy Jones said: ‘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.
‘Obviously you get fitter with training but your oxygen uptake stays fixed.
‘You could take a Tour de France cyclist and a man in the street and their oxygen uptake at the same work rate would be exactly the same.’
The benefits are likely to be due to the high levels of nitrate in beetroot juice, which costs around £2 a pint in health food shops.
The chemical is also found in green leafy vegetables such as lettuce and spinach but is especially concentrated in juices.
It is thought that it undergoes a series of changes in the body which lead to the blood vessels widening, improving oxygen supply to the muscles.
Although the study used shop-bought beetroot juice, the researchers said that homemade versions should also be beneficial.
But drinking beetroot juice is likely to have another unexpected consequence – purple urine, or ‘beeturia’ as it is known to scientists.