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.
