Beetroot juice boosts stamina by making muscles more fuel-efficient, scientists have found.
Last year the same researchers reported that the juice can increase physical endurance. The study focused on men aged 19 to 38 cycling on exercise bikes. Drinking 500ml of beetroot juice a day for a week enabled them to cycle 16 per cent longer before getting tired out. Now the scientists believe they understand how the beetroot boost works.
The new research showed beetroot juice doubled the amount of nitrate in the blood of volunteers, and reduced the rate at which muscles used their main source of energy. Beetroot juice helped muscles work more efficiently and lowered their oxygen uptake.
The scientists, from the University of Exeter's School of Sport and Health Sciences, believe nitrate from beetroot juice leads to increased levels of nitric oxide in the body, which affects a range of functions including blood flow, hormone levels and cell signalling. The findings are published in the Journal of Applied Physiology.
The study's leader, Professor Andy Jones, said: "We have seen growing interest in the benefits of drinking beetroot juice in the world of professional sport and I expect this study to attract even more attention from athletes."