Six days of supplementation with nitrate-rich beetroot juice led to a 3.4% average improvement in performance, compared to a nitrate-depleted beetroot juice, according to data published in Nutrients.
“As such, our findings suggest that nitrate supplementation could represent an effective nutritional strategy to improve exercise performance in soccer players, especially towards the end of the match when sprint intensity/frequency has been shown to decrease significantly due to fatigue,” wrote researcher from researchers from Maastricht University Medical Centre and the Institute of Sports and Exercise Studies at the HAN University of Applied Sciences in The Netherlands.
Growing interest
There has been increasing levels of interest in the potential benefits of beetroot juice for boosting athletic performance, particularly following a report in the Wall Street Journal that stated that the Auburn University football team drinks the juice before its games.
The majority of the science has been in support of the potential sports nutrition benefits of beetroot, linked to the nitrate concentration in the vegetable.
Recent studies have reported significant benefits for a range of athletes, including swimmers and cyclists.
The study used the standardized beetroot juice from UK company Beet It. The brand promotes its products with a claim of being backed by science. That claim is borne out by the company’s production process, which can standardize the amount of nitrate in the company’s 2.3-oz shots
“It reliably delivers 400 mg of nitrate in every serving. Beet It developed a process to adjust the amount of nitrate in every shot,” Joel Maharry, a marketing specialist and principal in the firm Ulrich Maharry that is coordinating the US launch, told us recently.
Study details
For the new study, the researchers recruited 32 male soccer players with an average age of 23 playing for Dutch amateur league clubs to participate in their randomized, double-blind cross-over study.
The players were randomly assigned to consume either a nitrate-rich (800 mg nitrate/day) or a nitrate-depleted beetroot juice for six days before completing a high intensity exercise. This was followed by at least eight days of “wash-out” before crossing over to the other intervention for another six days.
Results showed that consuming the nitrate-rich beetroot juice led to an 11-fold increase in plasma nitrate and 3-fold increase in plasma nitrite concentration.
Performance increased by 3.4% in the nitrate-rich group, compared to the placebo, nitrate-depleted juice group.
“Although the exact mode of action explaining this effect is still unclear, animal studies have shown that nitrate supplementation can increase blood flow, and enhance contractile function in type II muscle fibers,” wrote the researchers. “There is some suggestion that these adaptations might be responsible for the improved performance observed during high intensity/intermittent type exercise in which type II fibers are heavily recruited.”
A decrease in heart rate was also observed in the nitrate-rich beetroot juice group, compared to placebo.
“To the best of our knowledge, the current findings are the first evidence of changes in heart rate following nitrate ingestion in young healthy athletes,” they reported. “Whether the decrease in mean heart rate is related to the improved exercise performance is unclear, as the only available literature describing effects of inorganic nitrate-nitrite on heart rate are from heart failure patients
“While it is currently unclear whether nitrate and/or nitrite ingestion can similarly increase cardiac contractility in healthy individuals, such an effect could explain the decrease in heart rate observed in our study; i.e., allowing the same cardiac output with increased stroke volume, but lower heart rate.”
The study was funded by the Dutch Technology Foundation STW.
Source: Nutrients
2017, Volume 9, Number 3, Page 314; doi:10.3390/nu9030314
“Beetroot Juice Supplementation Improves High-Intensity Intermittent Type Exercise Performance in Trained Soccer Players”
Authors: J. Nyakayiru, et al.