Researchers have found that consuming dietary nitrate – the active molecule in beetroot juice – can increase muscle force while exercising, an advance that may lead to better workout supplements.
While previous studies have shown that dietary nitrate enhances exercise, it has remained unclear how the body converts this molecule into the chemical nitric oxide to be used by our cells.
In the new study, published earlier this month in the journal Acta Physiologica, scientists traced the distribution of ingested nitrate in the saliva, blood, muscle, and urine of ten healthy volunteers who performed leg exercises.
Scientists probed where in the body the dietary nitrate molecules were active to understand better the mechanisms in play.
During the workout, which included 60 thigh muscle contractions at maximum intensity for over five minutes, researchers found a significant increase in the nitrate levels in the quadriceps muscle.
They say the nitrate boost led to an increase in muscle force of about seven per cent, compared to when participants took a placebo.
“Our research has already provided a large body of evidence on the performance-enhancing properties of dietary nitrate, commonly found in beetroot juice,” said study co-author Andy Jones from the University of Exeter in the UK.
“Excitingly, this latest study provides the best evidence to date on the mechanisms behind why dietary nitrate improves human muscle performance,” Dr Jones added.
Earlier studies had discovered an increase of nitrate in tissue and body fluid after ingesting labeled dietary nitrate.
But in the new research, scientists could accurately assess where the nitrate is increased and active.
They were also able to shed new light on how the nitrate consumed is used up by the body to enhance exercise performance.
Citing a limitation of the study, researchers said while dietary nitrate supplementation often occurs in the form of beetroot juice, they say it is unclear how the results might have differed if the beverage had been consumed by the participants.
Since the research was conducted in a young male population, scientists say further studies are required to determine how women and older people responded to the supplementation.
“This study provides the first direct evidence that muscle nitrate levels are important for exercise performance, presumably by acting as a source of nitric oxide,” Barbora Piknova, another author of the study from the National Institutes of Health in the US, said.
“These results have significant implications not only for the exercise field, but possibly for other medical areas such as those targeting neuromuscular and metabolic diseases related to nitric oxide deficiency,” Dr Piknova added.