Effects of Beetroot Juice Supplementation on Cognitive Function, Aerobic and Anaerobic Performances of Trained Male Taekwondo Athletes: A Pilot Study

Abstract

Studies have shown that nitrate (NO3−)-rich beetroot juice (BJ) supplementation improves endurance and high-intensity intermittent exercise. The dose–response effects on taekwondo following BJ supplementation are yet to be determined. This study aimed to investigate two acute doses of 400 mg of NO3− (BJ-400) and 800 mg of NO3− (BJ-800) on taekwondo-specific performance and cognitive function tests compared with a placebo (PL) and control (CON) conditions. Eight trained male taekwondo athletes (age: 20 ± 4 years, height: 180 ± 2 cm, body mass: 64.8 ± 4.0 kg) completed four experimental trials using a randomized, double-blind placebo-controlled design: BJ-400, BJ-800, PL, and CON. Participants consumed two doses of BJ-400 and BJ-800 or nitrate-depleted PL at 2.5 h prior to performing the Multiple Frequency Speed of Kick Test (FSKT). Countermovement jump (CMJ) was performed before the (FSKT) and PSTT, whereas cognitive function was assessed (via the Stroop test) before and after supplementation and 10 min following PSTT. Blood lactate was collected before the CMJ tests immediately and 3 min after the FSKT and PSST; rating of perceived exertion (RPE) was recorded during and after both specific taekwondo tests. No significant differences (p > 0.05), with moderate and large effect sizes, between conditions were observed for PSTT and FSKT performances. In addition, blood lactate, RPE, heart rate, and CMJ height were not significantly different among conditions (p > 0.05). However, after the PSTT test, cognitive function was higher in BJ-400 compared to other treatments (p < 0.05). It was concluded that acute intake of 400 and 800 mg of NO3−rich BJ reported a moderate to large effect size in anaerobic and aerobic; however, no statistical differences were found in taekwondo-specific performance.

Nutritional Ergogenic Aids in Combat Sports: A Systematic Review and Meta-Analysis

“…Intake of 2 g/kg beetroot juice 150 min before the test in boxers did not produced differences in blood lactate levels or heart rate compared with the placebo group, but there was a significant decrease in power [41]. The same 1-day protocol with a controlled quantity of nitrate (NO 3 − ; 400 or 800 mg) in taekwondo practitioners did not produce differences in the number of kicks, general fitness (TTE, jump height, anaerobic performance and heart rate), blood lactate levels or perceptual training intensity [39]. However, 1 g of beetroot extract improved VO 2 peak (+10.0%) and the anaerobic threshold (+13.5%) compared with the placebo group without affecting blood lactate levels [40].…”

“…The level ranged from amateur to professional in both sexes, with a majority of male athletes (n = 726) compared with female athletes (n = 78) and nondetermined gender because the studies did not report it (n = 150) [27,34,37,45,57,58,[63][64][65]69]. Most studies focussed on grappling disciplines (n = 33) , followed by striking disciplines (n = 15) [23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41], mixed disciplines (n = 1) [75] and combat sports in general since they were not identified in the methodology (n = 2) [76,77]. In the case of NEAs, caffeine was the most evaluated supplement (n = 26) [23][24][25][26][27][28][29][30][42][43][44][45][46][47]…”

“…Most studies focussed on grappling disciplines (n = 33) , followed by striking disciplines (n = 15) [23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41], mixed disciplines (n = 1) [75] and combat sports in general since they were not identified in the methodology (n = 2) [76,77]. In the case of NEAs, caffeine was the most evaluated supplement (n = 26) [23][24][25][26][27][28][29][30][42][43][44][45][46][47][48][49][50][51][52][53][54][55][56][57][58], followed by plasma buffers (n = 19) [31]…”

“…The use of 6-12 mmol of NO 3 − contained in beetroot juice supplements produced significant im-provements in time to exhaustion in a 5-30 min cycling race, but slightly non-significant improvements in time trial or graded-exercise performance [80]. Regarding combat sports, neither 2 g/kg of beetroot juice [41] nor 400 and 800 mg of NO 3 − contained in the juice [39] produced performance advantages; indeed, there were negative effects on power compared with the placebo group [41]. Misinformation regarding the NO 3 − concentration of the product [41] did not permit determining whether the ergogenic dose established in other sports trials was achieved.…”

Dietary nitrate, aging and brain health: the latest evidence

“…Several studies have emerged in the past 18 months exploring the effects of acute/short-term dietary nitrate supplementation on cognitive function. Three of these studies [25,26,27 ▪ ] involved young, athletic participants and assessed cognitive function via performance on the Stroop test. This is a common cognitive test, used to measure certain aspects of executive function, selective attention and reaction time, in which participants are presented with the names of colors such as ‘red’, ‘green’, ‘blue’ and ‘yellow’.…”