“From a practical perspective, beetroot juice has the potential to be an effective performance-enhancing tool for recreational soccer players and athletes, particularly in sports where agility is critical (e.g., basketball),” wrote researchers in Japan.
Soccer players require the ability to quickly assess situations and make changes in direction and speed, abilities that are closely aligned with agility.
Agility is defined as “a rapid whole-body movement with change of velocity or direction in response to a stimulus”. Change-of-direction speed and decision-making factors are components of agility, relying on lower-limb muscle strength and cognitive function, respectively.
The short bursts of high-intensity exercise characteristic of soccer can temporarily impair executive functions, adversely affecting decision-making, reasoning and attention. This can be due to oxygen concentration and neurovascular mechanisms.
The nitrates in beetroot juice are converted to nitric oxide, which increases blood flow and oxygen to the brain and muscles. This may attenuate potential declines in cognitive performance and improve muscle power output.
The researchers noted that the positive effects of beetroot juice supplementation “may be most apparent during reduced oxygenation that occurs immediately after high-intensity sprinting,” counteracting declines in agility and performance that can sometimes follow high-intensity sprints.
Study details
The study was a crossover design involving 21 male soccer players who were randomized to consume a single 70 mL dose of concentrated beetroot juice containing 400 mg of nitrates, or a placebo vegetable juice before completing three sets of 6 × 20 m all-out sprints
Following a three-day washout period, the participants consumed the other drink and performed the same exercise. The researchers measured salivary nitrate concentration and blood pressure.
The soccer players completed several tests using sensors to evaluate simple response time, choice response time and change-of-direction speed following intake of beetroot juice compared to placebo. A Y-shaped agility test evaluated choice response time and cognitive processing abilities during movement, and a T-test was used to evaluate change-of-direction speed.
“Under practical field-based conditions, acute beetroot juice intake enhanced post-sprint agility and change-of-direction performance, particularly [choice response time] and [change-of-direction speed],” the researchers wrote.
Simple response time did not differ between the beetroot juice and placebo groups. Compared to placebo, salivary nitrates increased, and blood pressure decreased in the beetroot juice group.
“These results provide new evidence that beetroot juice may improve agility-related performance in sports requiring rapid decision making and change-of-direction movements, particularly under post-sprint conditions,” they wrote.
They called for further studies with larger sample sizes and the incorporation of objective biochemical tests. They also noted the limitation of the placebo vegetable juice tasting different from beetroot juice, potentially leading to biased results.
Source: Nutrients. doi: 10.3390/nu18060897. “Influence of Acute Beetroot Juice Intake on Agility Performance Immediately Post-Repeated Maximal Sprinting in Soccer Players”. Authors: X. Yang et al.
