Effect of Beetroot Juice Supplementation on Mood, Perceived Exertion, and Performance During a 30-Second Wingate Test

Nutritional Ergogenic Aids in Cycling: A Systematic Review

This systematic review aimed to evaluate the effectiveness of the independent or combined use of nutritional ergogenic aids belonging to Group A of the ABCD classification by the Australian Institute of Sport (AIS) in the context of cycling (caffeine, creatine, sodium bicarbonate, beta-alanine, nitrates, and glycerol). A comprehensive search was carried out using three databases: PubMed, Scopus, and Web of Science. All the databases were searched for Randomized Controlled Trials or crossover design studies assessing the effects of supplementation on cycling performance in comparison with placebos in healthy adults. The methodological quality of each study was evaluated using the Physiotherapy Evidence Database scale. Thirty-six articles involving 701 participants were included in this review, examining supplementation with caffeine (n = 5), creatine (n = 2), sodium bicarbonate (n = 6), beta-alanine (n = 3), and nitrates (n = 8). Additionally, supplemental combinations of caffeine and creatine (n = 3), caffeine and sodium bicarbonate (n = 3), caffeine and nitrates (n = 1), creatine and sodium bicarbonate (n = 1), and sodium bicarbonate and beta-alanine (n = 4) were analyzed. A benefit for cyclists' athletic performnce was found when consuming a caffeine supplement, and a potential positive effect was noted after the consumption of sodium bicarbonate, as well as after the combination of caffeine and creatine. However, no statistically significant effects were identified for the remaining supplements, whether administered individually or in combination.

Impact of a short-term nitrate and citrulline co-supplementation on sport performance in elite rowers: a randomized, double-blind, placebo-controlled crossover trial

PURPOSE

Citrulline (CIT) and beetroot extract (BR) have separately shown benefits in rowing performance-related outcomes. However, effects of combined supplementation remain to be elucidated. The main purpose of this research was to study the effects of 1 week of daily co-supplementation of 3.5 g BR (500 mg NO3-) plus 6 g CIT on aerobic performance, maximal strength, and high-intensity power and peak stroke in elite male rowers compared to a placebo and to a BR supplementation.

METHODS

20 elite rowers participated in this randomized, double-blind, placebo-controlled crossover trial completing 1 week of supplementation in each group of study: Placebo group (PLAG); BR group (BRG); and BR + CIT group (BR-CITG). 3 main physical tests were performed: aerobic performance, Wingate test and CMJ jump, and metabolic biomarkers and physiological outcomes were collected.

RESULTS

The Wingate all-out test showed no between-condition differences in peak power, mean power, relative power, or fatigue index (P > 0.05), but clearance of lactate was better in BR-CITG (P < 0.05). In the performance test, peak power differed only between PLAG and BR-CITG (P = 0.036), while VO2peak and maximum heart rate remained similar. CMJ jumping test results showed no between-condition differences, and blood samples were consistent (P > 0.200).

CONCLUSION

Supplementation with 3.5 g of BR extract plus 6 g of CIT for 7 days improved lactate clearance after Wingate test and peak power in a performance test. No further improvements were found, suggesting longer period of supplementation might be needed to show greater benefits.

Exploring the Impact of Alternative Sources of Dietary Nitrate Supplementation on Exercise Performance

An increase in the level of nitric oxide (NO) plays a key role in regulating the human cardiovascular system (lowering blood pressure, improving blood flow), glycemic control in type 2 diabetes, and may help enhance exercise capacity in healthy individuals (including athletes). This molecule is formed by endogenous enzymatic synthesis and the intake of inorganic nitrate (NO3-) from dietary sources. Although one of the most well-known natural sources of NO3- in the daily diet is beetroot (Beta vulgaris), this review also explores other plant sources of NO3- with comparable concentrations that could serve as ergogenic aids, supporting exercise performance or recovery in healthy individuals. The results of the analysis demonstrate that red spinach (Amaranthus spp.) and green spinach (Spinacia oleracea) are alternative natural sources rich in dietary NO3-. The outcomes of the collected studies showed that consumption of selected alternative sources of inorganic NO3- could support physical condition. Red spinach and green spinach have been shown to improve exercise performance or accelerate recovery after physical exertion in healthy subjects (including athletes).

Investigating sedentariness and health status of primary school teachers in Ghana

OBJECTIVE

Physical inactivity is linked to chronic illnesses and disabilities among workers, especially those in high demanding jobs like teachers. Despite the global prominence of sedentary behavior research, studies drawing the relationships between physical inactivity and multimorbidity among working teacher populations in low-and middle-countries remain untapped. This study assessed the sedentariness and health status of primary school teachers in Cape Coast Metropolis in Ghana.

METHOD

This cross-sectional survey employed 1109 primary school teachers from the Cape Coast Metropolis in the Central Region of Ghana, targeting the entire population.

RESULTS

Generally, the teachers were highly sedentary and reported poor health status. Other results showed no difference in sedentariness across gender, (n = 1107, t= -0.32, p > 0.05). However, female teachers suffer more pain and discomfort, (n = 1103.51), t = - 3.07, p < 0.05), anxiety and depression, (n = 1099.56), t = - 2.85, p < 0.000), and poor health status (n = 1107), t = 2.14, p < 0.05), than their male counterparts. Also, pain and discomfort, anxiety and depression, health status and years of work significantly predicted sedentariness among the teachers, F (4, 1104) = 5.966, p = 0.00, R = 0.145, R2 = 0.029, adjusted R2 = 0.018.

CONCLUSION

The findings suggest that individualized or personalized interventions are urgently needed to promote regular physical activity to improve the health status and reduce associated complications on the health and well-being, especially among the female primary school teachers. Given the health risks of sedentary lifestyle, behavioral interventions at the person-level (i.e., individualized- routine weekly physical activity programs) and built environmental restructuring (e.g., creation of walkways to encourage regular walking) could be done to improve physical activity behavior among teachers within the Cape Coast Metropolis, and perhaps beyond.

Effects of dietary nitrate supplementation on peak power output: Influence of supplementation strategy and population

Increasing evidence indicates that dietary nitrate supplementation has the potential to increase muscular power output during skeletal muscle contractions. However, there is still a paucity of data characterizing the impact of different nitrate dosing regimens on nitric oxide bioavailability and its potential ergogenic effects across various population groups. This review discusses the potential influence of different dietary nitrate supplementation strategies on nitric oxide bioavailability and muscular peak power output in healthy adults, athletes, older adults and some clinical populations. Effect sizes were calculated for peak power output and absolute and/or relative nitrate doses were considered where applicable. There was no relationship between the effect sizes of peak power output change following nitrate supplementation and when nitrate dosage when considered in absolute or relative terms. Areas for further research are also recommended including a focus on nitrate dosing regimens that optimize nitric oxide bioavailability for enhancing peak power at times of increased muscular work in a variety of healthy and disease populations.

Dietary nitrate ingested with and without pomegranate supplementation does not improve resistance exercise performance

This study tested the hypothesis that co-ingesting nitrate (NO₃^-)-rich beetroot juice (BR) and pomegranate powder (POM) would enhance neuromuscular performance during vertical countermovement jumps, explosive kneeling countermovement push-ups, and back squats compared to BR ingestion alone. Fifteen recreationally-active males were assigned in a double-blind, randomized, crossover design, to supplement in 3 conditions: (1) NO₃^--depleted beetroot juice (PL; 0.10 mmol NO₃^-) with two empty gelatin capsules; (2) NO₃^--rich beetroot juice (BR; 11.8 mmol NO₃^-) with two empty gelatin capsules, and (3) BR with 1,000 mg of POM powder in two capsules (BR + POM). Participants completed 5 countermovement jumps and 5 kneeling countermovement push-ups interspersed by 1  min of recovery. Subsequently, participants performed 2 sets of 2 × 70% one-repetition maximum back squats, interspersed by 2  min of recovery. Plasma [NO₃^-] and nitrite ([NO₂^-]) were elevated following BR and BR + POM compared with PL and POM (p < 0.001) with no differences between BR and BR + POM (p > 0.05) or PL and POM (p > 0.05). Peak power during countermovement jumps increased by 3% following BR compared to BR + POM (88.50 ± 11.46 vs. 85.80 ± 10.14 W/Kg^0.67, p = 0.009) but not PL (88.50 ± 11.46 vs. 85.58 ± 10.05 W/Kg^0.67, p = 0.07). Neuromuscular performance was not different between conditions during explosive kneeling push-ups and back squats (p > 0.05). These data provide insight into the efficacy of NO₃^- to modulate explosive resistance exercise performance and indicate that supplementing with BR alone or combined with POM has limited ergogenic potential on resistance exercise. Furthermore, caution is required when combining BR with POM, as this could compromise aspects of resistance exercise performance, at least when compared to BR ingested independently.

Photobiomodulation does not improve anaerobic performance in well-trained cyclists

To determine if photobiomodulation (PBM) has ergogenic effects on the anaerobic performance of well-trained cyclists. Fifteen healthy male road or mountain bike cyclists participated in this randomized, double-blinded, placebo-controlled, crossover study. Athletes were randomly assigned to receive photobiomodulation (630 nm, 4.6 J/cm², 6 J per point, 16 points, PBM session) or placebo intervention (PLA session) in the first session. The athletes then performed a 30-s Wingate test to determine mean and peak average power, relative power, mean and peak velocity, mean and peak RPM, fatigue index, total distance, time to peak power, explosive strength, and power drop. After 48 h, athletes returned to the laboratory for the crossover intervention. The repeated-measures ANOVA test followed by Bonferroni post hoc test or Friedman test with Dunn's post hoc test (p < 0.05), and Cohen's d statistic were used for comparisons. Performance in the Wingate test was not significantly different (p > 0.05) between PBM and PLA sessions for any variable. Only a small effect size was detected for time to peak power (-0.40; 1.11 to 0.31) and explosive strength (0.38; -0.34 to 1.09). We conclude that irradiation with red light, under a low energy density, does not promote ergogenic effects on the anaerobic performance of cycling athletes.

Effects of Dietary Nitrate Supplementation on Performance during Single and Repeated Bouts of Short-Duration High-Intensity Exercise: A Systematic Review and Meta-Analysis of Randomised Controlled Trials

Inorganic nitrate (NO₃^-) has emerged as a potential ergogenic aid over the last couple of decades. While recent systematic reviews and meta-analyses have suggested some small positive effects of NO₃^- supplementation on performance across a range of exercise tasks, the effect of NO₃^- supplementation on performance during single and repeated bouts of short-duration, high-intensity exercise is unclear. This review was conducted following PRISMA guidelines. MEDLINE and SPORTDiscus were searched from inception to January 2023. A paired analysis model for cross-over trials was incorporated to perform a random effects meta-analysis for each performance outcome and to generate standardized mean differences (SMD) between the NO₃^- and placebo supplementation conditions. The systematic review and meta-analysis included 27 and 23 studies, respectively. Time to reach peak power (SMD: 0.75, p = 0.02), mean power output (SMD: 0.20, p = 0.02), and total distance covered in the Yo-Yo intermittent recovery level 1 test (SMD: 0.17, p < 0.0001) were all improved after NO₃^- supplementation. Dietary NO₃^- supplementation had small positive effects on some performance outcomes during single and repeated bouts of high-intensity exercise. Therefore, athletes competing in sports requiring single or repeated bouts of high-intensity exercise may benefit from NO₃^- supplementation.

Effects of Dietary Nitrate Supplementation on Back Squat and Bench Press Performance: A Systematic Review and Meta-Analysis

This systematic review and meta-analysis investigated the influence of dietary nitrate supplementation on resistance exercise performance according to the PRISMA guidelines. Searches were conducted on MEDLINE, PubMed, ScienceDirect, Scopus and SPORTDiscus databases up to April 2023. Inclusion criteria were adult resistance-trained males who supplemented with a nitrate-rich supplement and nitrate-deficient placebo to assess repetitions-to-failure (RTF), peak power, mean power, peak velocity, and/or mean velocity during back squat and bench press exercise. A random effects model was performed on six studies and showed that nitrate supplementation improved RTF (standardized mean difference [SMD]: 0.43, 95% confidence intervals [95% CI]: 0.156 to 0.699, p = 0.002), mean power (SMD: 0.40, 95% CI: 0.127 to 0.678, p = 0.004), and mean velocity (SMD: 0.57, 95% CI: 0.07 to 1.061, p = 0.025) but had no effect on peak power (SMD: 0.204, 95% CI: -0.004 to 0.411, p = 0.054) or peak velocity (SMD: 0.00, 95% CI: -0.173 to 0.173, p = 1.000) when back squat and bench press were combined. Subgroup analyses revealed that back squats were more likely to be enhanced and that a dosing regimen may influence the efficacy of nitrate supplementation. Overall, nitrate supplementation had a small beneficial effect on some aspects of resistance exercise performance, but there were limited studies available and the variability was large. Additional studies that focus on upper and lower body resistance exercise and nitrate dosage are required to elucidate the efficacy of dietary nitrate supplementation on resistance exercise performance.

Effects of dietary nitrate supplementation on muscular power output: Influence of supplementation strategy and population

Increasing evidence indicates that dietary nitrate supplementation has the potential to increase muscular power output during skeletal muscle contractions. However, there is still a paucity of data characterizing the impact of different nitrate dosing regimens on nitric oxide bioavailability its potential ergogenic effects across various population groups. This narrative review discusses the potential influence of different dietary nitrate supplementation strategies on nitric oxide bioavailability and muscular power output in healthy adults, athletes, older adults and some clinical populations. Areas for further research are also recommended including a focus individualized nitrate dosing regimens to optimize nitric oxide bioavailability and to promote muscular power enhancements in different populations.

The Effect of Dietary Nitrate on the Contractile Properties of Human Skeletal Muscle: A Systematic Review and Meta-Analysis

The propose of this study was to systematically review the current literature and meta-analyse the effects of dietary nitrate (NO₃^-) supplementation on the contractile properties of skeletal muscle. A literature search of three databases was conducted in June 2021, with 19 studies meeting the inclusion criteria. Studies were included if a placebo versus dietary NO₃^--only supplementation protocol was used in healthy human, assessed muscle contraction or activities that was < 3 minutes in duration and focused on the lower-body. For the meta-analysis, a pooled standardised mean difference (SMD) was determined for maximum voluntary contraction (MVC) (n = 11), cycling, running and inertial load squad peak power output (PPO) (n = 8), mean power output (MPO) (n = 6) and time to PPO (n = 4). NO₃^- supplementation demonstrated a small improvement in PPO (SMD = 0.25, P = 0.030) and MPO (SMD = 0.28, P = 0.030) when compared to the placebo. NO₃^- also resulted in an enhanced time to PPO (SMD = -0.78, P < 0.001). There was no clear effect of NO₃^- on isometric MVC (SMD = 0.03, P = 0.758). This review reports that NO₃^- supplementation may have potential to enhance PPO, MPO and time to PPO during dynamic exercise, which may transfer to brief explosive actions commonly observed in sporting activities. Due to the variability in studies, we encourage researchers to use this work to explore areas where evidence in lacking and standardize the study design and procedures.Key teaching pointsFindings from this meta-analysis highlight the potential positive ergogenic effect of dietary NO3-supplementation on PPO, MPO and time to PPO during short duration (<10 s) dynamic exercise.NO3- supplementation might be considered as an ergogenic aid when executing power-based actions (e.g., 100 m sprinter or weightlifter).This review highlights that further research is required to address some of the contrasting findings presented here using a standardised procedure to allow for improved synthesis.

Does Beetroot Supplementation Improve Performance in Combat Sports Athletes? A Systematic Review of Randomized Controlled Trials

While studies on dietary nitrate (NO₃^-) supplementation and its impact on combat sports performance are increasing, finite conclusions from currently available investigations remain unclear. Thus, the present systematic review examined the acute and chronic ergogenic effect(s) of dietary nitrate intake from beetroot on different aspects of combat sports performance. A systematic search for randomized placebo-controlled studies investigating the effects of beetroot supplementation on combat sports outcomes was performed through Scopus, PubMed/MEDLINE, Web of Science, Scielo, Sport Discus, and Cochrane Library databases up to 2 January 2023. The different terms related to beetroot and to combat sports were connected in the search strategies using the Boolean operators 'AND' and 'OR'. A total of nine studies with good methodological quality (based on the Cochrane risk of bias tool) fulfilled the inclusion criteria. Seven studies used an acute supplementation strategy, while the other two studies utilized chronic supplementation. Findings showed beetroot intake may be an effective tool to improve oxidative metabolism and muscle force production (i.e., isokinetic and isometric) in combat sports athletes. However, these effects may depend on the population, intake duration, muscle group activated, and exercise type. Future studies are required to (1) understand the effects on female athletes and (2) elucidate the impacts of dosing protocols and specific exercise modalities for enhancing combat sports performance.

Effects of beetroot juice intake on repeated performance of competitive swimmers

Background: Beetroot juice is a sport supplement with a high level of evidence on the physical performance enhancement. However, in swimming, there is no clear data about the effects of beetroot juice on performance. Objective: To investigate whether an acute intake of beetroot juice (BJ) improves the performance of competitive swimmers in a repeated maximum swimming effort. Method: Thirteen national-level swimmers (six females and seven males), participated in this randomized, double-blind crossover study. In two different trials, swimmers ingested a 70-mL placebo shot (.04 mmol NO₃ ^-; PLA) or a 70-mL Beet-It shot (6.4 mmol of NO₃ ^-beet juice [BJ]) 3 h before undergoing a 6 × 100-m front-crawl maximal effort test with 7 min rest between each 100 m. Results: Overall, 100-m times showed no difference between the BJ and PLA groups (p = .364), although a possibly shorter time was observed for BJ in the last repetition (p = .104; mean difference [MD] = -.99 s, mean-based inference [MBI] = 49/51/0). Participants in the BJ condition showed a possibly lower rate of perceived exertion in the first (p = .242, MD = -.85, MBI = 70/28/2) and second repetitions (p = .165, MD = 1.15, MBI = 83/16/1), whereas Total Quality Recovery scale scores were likely higher in the first (p = .110, MD = 1.15, MBI = 83/16/1) and third (p = .082, MD = -.77, MBI = 70/29/1) repetitions compared with those in the PLA group. Blood lactate concentration [La⁺] levels showed no differences between groups in any of the repetitions (p > .05, unclear), and we observed an increase in 100-m times for both BJ and PLA (BJ: p = .014, MD = -1.51 s; PLA: p = .029, MD = -1.57 s) after the fifth repetition. Conclusion: No clear differences in performance were observed in a 6 × 100-m repeated sprint test by competitive swimmers when supplementing (or not) with BJ. However, there was a trend toward a better recovery between efforts and a better tolerance of fatigue when swimmers ingested BJ.

Dietary Nitrate Supplementation Enhances Performance and Speeds Muscle Deoxyhaemoglobin Kinetics during an End-Sprint after Prolonged Moderate-Intensity Exercise

Short-term dietary nitrate (NO3−) supplementation has the potential to enhance performance during submaximal endurance, and short-duration, maximal-intensity exercise. However, it has yet to be determined whether NO3− supplementation before and during submaximal endurance exercise can improve performance during a short-duration, maximal-intensity end-sprint. In a randomised, double-blind, crossover study, 9 recreationally active men ingested NO3−-rich (BR: 8 mmol NO3−/day) and NO3−-depleted (PL: 0.75 mmol NO3−/day) beetroot powder for 7 days. On day 7, participants completed 2 h of moderate-intensity cycling, which immediately transitioned into a 60 s maximal-intensity end-sprint, with supplements ingested 2 h before and 1 h into the moderate-intensity exercise bout. Plasma [NO3−] and [NO2−] were higher in BR compared to PL pre- and post-exercise (p < 0.05). Post-exercise plasma [NO3−] was higher than pre-exercise (562 ± 89 µM vs. 300 ± 73 µM; p < 0.05) and plasma [NO2−] was not significantly different pre- (280 ± 58 nM) and post-exercise (228 ± 63 nM) in the BR condition (p > 0.05). Mean power output during the final 30 s of the end-sprint was greater after BR (390 ± 38 W) compared to PL (365 ± 41 W; p < 0.05). There were no differences between BR and PL in any muscle oxygenation variables during moderate-intensity cycling (p > 0.05), but muscle [deoxyhaemoglobin] kinetics was faster during the end-sprint in BR (6.5 ± 1.4 s) compared to PL (7.3 ± 1.4 s; p < 0.05). These findings suggest that NO3− supplementation has the potential to improve end-sprint performance in endurance events when ingested prior to and during exercise.

Influence of Beetroot Juice Ingestion on Neuromuscular Performance on Semi-Professional Female Rugby Players: A Randomized, Double-Blind, Placebo-Controlled Study

PURPOSE

Beetroot juice (BRJ) is considered an ergogenic aid with good to strong evidence for improving human performance in sport modalities with similar demands to rugby. However, most of the studies were realized in male athletes with limited evidence in female athletes. Thus, the aim of this study was to explore the acute ingestion of BRJ in female rugby players.

METHODS

Fourteen semi-professional female rugby players (25.0 ± 3.7 years) belonging to a team from the First Spanish Female Rugby Division participated in this study. Participants were randomly divided into two groups that realized a neuromuscular battery after BRJ (140mL, 12.8 mmol NO₃^-) or placebo (PLAC, 140 mL, 0.08 mmol NO₃^-) ingestion on two different days separated by one week between protocols. The neuromuscular test battery consisted of a countermovement jump (CMJ), isometric handgrip strength (i.e., dominant), 10-m and 30-m sprint, agility t-test and Bronco test. Afterwards, participants reported a rate of perception scale (6-20 points) and side effects questionnaire associated with BRJ or PLAC ingestion.

RESULTS

Statistically significant improvements were observed in CMJ (7.7%; p = 0.029; ES = 0.62), while no differences were reported in dominant isometric handgrip strength (-1.7%; p = 0.274; ES = -0.20); 10-m and 30-m sprint (0.5-0.8%; p = 0.441-0.588; ES = 0.03-0.18); modified agility t-test (-0.6%; p = 0.503; ES = -0.12) and Bronco test (1.94%; p = 0.459; ES = 0.16).

CONCLUSIONS

BRJ ingestion could improve neuromuscular performance in the CMJ test, while no differences in sprint (10-m and 30-m sprint test), agility, isometric handgrip strength and endurance performance (i.e., Bronco test) were reported.

Acute Effects of Beetroot Juice Supplementation on Isometric Muscle Strength, Rate of Torque Development and Isometric Endurance in Young Adult Men and Women: A Randomized, Double-Blind, Controlled Cross-Over Pilot Study

This study was conducted to investigate the effect of concentrated beetroot juice on isometric strength and knee extensor muscle endurance in healthy adults. We conducted a randomized cross-over, double-blind experiment in which participants (18 healthy, physically active adults, 9 men, 9 women) consumed either concentrated beetroot juice (140 mL) or low-nitrate control supplement 2.5 h before the measurement. Isometric maximum strength (peak torque), explosive strength (isometric rate of torque development), and strength endurance at 50% of peak torque were measured on an isometric dynamometer. The results showed that concentrated beetroot juice had no effect on the maximum voluntary isometric strength and rate of torque development of the knee extensors. The only exception was the maximum rate of torque development, for which a positive influence was demonstrated only in men. As for the endurance of the knee extensors, the supplement had a positive effect in men (endurance time increased from 86.4 ± 46.1 s to 103.4 ± 53.7 s; p = 0.022), but not in women. The absence of effect on maximal voluntary strength is consistent with previous research. One the other hand, improvements in endurance and rate of torque development in men only point to an important aspect of a previously under-researched area of sex-specific responses to nitrate supplementation.

Effects of Dietary Nitrate Supplementation on Performance and Muscle Oxygenation during Resistance Exercise in Men

The purpose of the current study was to assess the effects of acute and short-term nitrate (NO3−)-rich beetroot juice (BR) supplementation on performance outcomes and muscle oxygenation during bench press and back squat exercise. Fourteen recreationally active males were assigned in a randomized, double-blind, crossover design to supplement for 4 days in two conditions: (1) NO3−-depleted beetroot juice (PL; 0.10 mmol NO3− per day) and (2) BR (11.8 mmol NO3− per day). On days 1 and 4 of the supplementation periods, participants completed 2 sets of 2 × 70%1RM interspersed by 2 min of recovery, followed by one set of repetitions-to-failure (RTF) at 60%1RM for the determination of muscular power, velocity, and endurance. Quadriceps and pectoralis major tissue saturation index (TSI) were measured throughout exercise. Plasma [NO3−] and nitrite ([NO2−]) were higher after 1 and 4 days of supplementation with BR compared to PL (p < 0.05). Quadriceps and pectoralis major TSI were not different between conditions (p > 0.05). The number of RTF in bench press was 5% greater after acute BR ingestion compared to PL (PL: 23 ± 4 vs. BR: 24 ± 5, p < 0.05). There were no differences between BR and PL for RTF for back squat or power and velocity for back squat or bench press (p > 0.05). These data improve understanding on the ergogenic potential of BR supplementation during resistance exercise.

Effects of Citrulline Supplementation on Different Aerobic Exercise Performance Outcomes: A Systematic Review and Meta-Analysis

Supplementation with Citrulline (Cit) has been shown to have a positive impact on aerobic exercise performance and related outcomes such as lactate, oxygen uptake (VO₂) kinetics, and the rate of perceived exertion (RPE), probably due to its relationship to endogenous nitric oxide production. However, current research has shown this to be controversial. The main objective of this systematic review and meta-analysis was to analyze and assess the effects of Cit supplementation on aerobic exercise performance and related outcomes, as well as to show the most suitable doses and timing of ingestion. A structured literature search was carried out by the PRISMA^® (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) and PICOS guidelines in the following databases: Pubmed/Medline, Scopus, and Web of Science (WOS). A total of 10 studies were included in the analysis, all of which exclusively compared the effects of Cit supplementation with those of a placebo group on aerobic performance, lactate, VO₂, and the RPE. Those articles that used other supplements and measured other outcomes were excluded. The meta-analysis was carried out using Hedges’ g random effects model and pooled standardized mean differences (SMD). The results showed no positive effects of Cit supplementation on aerobic performance (pooled SMD = 0.15; 95% CI (−0.02 to 0.32); I², 0%; p = 0.08), the RPE (pooled SMD = −0.03; 95% CI (−0.43 to 0.38); I², 49%; p = 0.9), VO₂ kinetics (pooled SMD = 0.01; 95% CI (−0.16 to 0.17); I², 0%; p = 0.94), and lactate (pooled SMD = 0.25; 95% CI (−0.10 to 0.59); I², 0%; p = 0.16). In conclusion, Cit supplementation did not prove to have any benefits for aerobic exercise performance and related outcomes. Where chronic protocols seemed to show a positive tendency, more studies in the field are needed to better understand the effects.

The effects of nitrate ingestion on high-intensity endurance time-trial performance: A systematic review and meta-analysis

Background/Objective

Dietary nitrate ingestion extends endurance capacity, but data supporting endurance time-trial performance are unclear. This systematic review and meta-analysis evaluated the evidence for dietary nitrate supplementation to improve high-intensity endurance time-trial performance over 5–30 min on the premise that nitrate may alleviate peripheral fatigue over shorter durations.

Methods

A systematic literature search and data extraction was carried out following PRISMA guidelines and the PICOS framework within five databases: PubMed, ProQuest, ScienceDirect, Scopus and SPORTDiscus. Search terms used were: (nitrate OR nitrite OR beetroot) AND (high intensity OR all out) AND (time trial or total work done) AND performance.

Results

Twenty-four studies were included. Fifteen studies applied an acute supplementation strategy (4.1 mmol–15.2 mmol serving on one day), eight chronic supplementation (4.0 mmol–13.0 mmol per day over 3–15 days), and one applied both acute and chronic supplementation (8.0 mmol on one day and over 15 days). Standardised mean difference for time-trial ranging from 5 to 30 min showed an overall trivial effect in favour of nitrate (Hedges'g = 0.15, 95% CI -0.00 to 0.31, Z = 1.95, p = 0.05). Subgroup analysis revealed a small, borderline effect in favour of chronic nitrate intervention (Hedges'g = 0.30, 95% CI -0.00 to 0.59, Z = 1.94, p = 0.05), and a non-significant effect for acute nitrate intervention (Hedges'g = 0.10, 95% CI -0.08 to 0.28, Z = 1.11, p = 0.27).

Conclusion

Chronic nitrate supplementation improves time-trial performance ranging from 5 to 30 min.

Acute Effects of Beetroot Juice Supplements on Lower-Body Strength in Female Athletes: Double-Blind Crossover Randomized Trial

BACKGROUND

Beetroot juice (BRJ) is used as an ergogenic aid, but no previous study has analyzed the effect this supplement has on the production of explosive force and muscular endurance in physically active women.

HYPOTHESIS

BRJ improves explosive force and muscular endurance in the lower limbs of physically active women.

STUDY DESIGN

Randomized double-blind crossover study.

LEVEL OF EVIDENCE

Level 3.

METHODS

Fourteen physically active women performed a countermovement jump (CMJ) test, a back squat test for assessing velocity and power at 50% and 75% of one-repetition maximum (1RM), and the number of repetitions on a muscular endurance test consisting of 3 sets at 75% of 1RM in a resistance training protocol comprising 3 exercises (back squat, leg press, and leg extension). The participants performed the test in 2 sessions, 150 minutes after ingesting 70 mL of either BRJ (400 mg of nitrate) or a placebo (PLA).

RESULTS

A greater maximum height was achieved in the CMJ after consuming BRJ compared with a PLA (P = 0.04; effect size (ES) = 0.34). After a BRJ supplement at 50% 1RM, a higher mean velocity [+6.7%; P = 0.03; (ES) = 0.39 (-0.40 to 1.17)], peak velocity (+6%; P = 0.04; ES = 0.39 [-0.40 to 1.17]), mean power (+7.3%; P = 0.02; ES = 0.30 [-0.48 to 1.08]) and peak power (+6%; P = 0.04; ES = 0.20 [-0.59 to 0.98]) were attained in the back squat test. In the muscular endurance test, BRJ increased performance compared with the PLA (P < 0.00; η_p² = 0.651).

CONCLUSION

BRJ supplements exert an ergogenic effect on the ability to produce explosive force and muscular endurance in the lower limbs in physically active women.

CLINICAL RELEVANCE

If physically active women took a BRJ supplement 120 minutes before resistance training their performance could be enhanced.

The Effects of Dietary Nitrate Supplementation on Explosive Exercise Performance: A Systematic Review

Dietary nitrate supplementation is evidenced to induce physiological effects on skeletal muscle function in fast-twitch muscle fibers and may enhance high-intensity exercise performance. An important component of sport-specific skills is the ability to perform explosive movements; however, it is unclear if nitrate supplementation can impact explosive efforts. We examined the existing evidence to determine whether nitrate supplementation improves explosive efforts lasting ≤ 6 s. PubMed, Scopus and Directory of Open Access Journals (DOAJ) were searched for articles using the following search strategy: (nitrate OR nitrite OR beetroot) AND (supplement OR supplementation) AND (explosive OR power OR high intensity OR high-intensity OR sprint* OR “athletic performance”). Out of 810 studies, 18 were eligible according to inclusion criteria. Results showed that 4 of the 10 sprint-type studies observed improved sprint time, power output, and total work in cycling or running, whereas 4 of the 10 resistance-based exercise studies observed improvements to power and velocity of free-weight bench press as well as isokinetic knee extension and flexion at certain angular velocities. These results suggest that nitrate potentially improves explosive exercise performance, but further work is required to clarify the factors influencing the efficacy of nitrate in different exercise modalities.

The Effect of Beetroot Ingestion on High-Intensity Interval Training: A Systematic Review and Meta-Analysis

Dietary nitrate supplementation has shown promising ergogenic effects on endurance exercise. However, at present there is no systematic analysis evaluating the effects of acute or chronic nitrate supplementation on performance measures during high-intensity interval training (HIIT) and sprint interval training (SIT). The main aim of this systematic review and meta-analysis was to evaluate the evidence for supplementation of dietary beetroot-a common source of nitrate-to improve peak and mean power output during HIIT and SIT. A systematic literature search was carried out following PRISMA guidelines and the PICOS framework within the following databases: PubMed, ProQuest, ScienceDirect, and SPORTDiscus. Search terms used were: ((nitrate OR nitrite OR beetroot) AND (HIIT or high intensity or sprint interval or SIT) AND (performance)). A total of 17 studies were included and reviewed independently. Seven studies applied an acute supplementation strategy and ten studies applied chronic supplementation. The standardised mean difference for mean power output showed an overall trivial, non-significant effect in favour of placebo (Hedges' g = -0.05, 95% CI -0.32 to 0.21, Z = 0.39, p = 0.69). The standardised mean difference for peak power output showed a trivial, non-significant effect in favour of the beetroot juice intervention (Hedges' g = 0.08, 95% CI -0.14 to 0.30, Z = 0.72, p = 0.47). The present meta-analysis showed trivial statistical heterogeneity in power output, but the variation in the exercise protocols, nitrate dosage, type of beetroot products, supplementation strategy, and duration among studies restricted a firm conclusion of the effect of beetroot supplementation on HIIT performance. Our findings suggest that beetroot supplementation offers no significant improvement to peak or mean power output during HIIT or SIT. Future research could further examine the ergogenic potential by optimising the beetroot supplementation strategy in terms of dosage, timing, and type of beetroot product. The potential combined effect of other ingredients in the beetroot products should not be undermined. Finally, a chronic supplementation protocol with a higher beetroot dosage (>12.9 mmol/day for 6 days) is recommended for future HIIT and SIT study.

Effect of dietary nitrate on human muscle power: a systematic review and individual participant data meta-analysis

BACKGROUND

Previous narrative reviews have concluded that dietary nitrate (NO3-) improves maximal neuromuscular power in humans. This conclusion, however, was based on a limited number of studies, and no attempt has been made to quantify the exact magnitude of this beneficial effect. Such information would help ensure adequate statistical power in future studies and could help place the effects of dietary NO3- on various aspects of exercise performance (i.e., endurance vs. strength vs. power) in better context. We therefore undertook a systematic review and individual participant data meta-analysis to quantify the effects of NO3- supplementation on human muscle power.

METHODS

The literature was searched using a strategy developed by a health sciences librarian. Data sources included Medline Ovid, Embase, SPORTDiscus, Scopus, Clinicaltrials.gov , and Google Scholar. Studies were included if they used a randomized, double-blind, placebo-controlled, crossover experimental design to measure the effects of dietary NO3- on maximal power during exercise in the non-fatigued state and the within-subject correlation could be determined from data in the published manuscript or obtained from the authors.

RESULTS

Nineteen studies of a total of 268 participants (218 men, 50 women) met the criteria for inclusion. The overall effect size (ES; Hedge's g) calculated using a fixed effects model was 0.42 (95% confidence interval (CI) 0.29, 0.56; p = 6.310 × 10- 11). There was limited heterogeneity between studies (i.e., I2 = 22.79%, H2 = 1.30, p = 0.3460). The ES estimated using a random effects model was therefore similar (i.e., 0.45, 95% CI 0.30, 0.61; p = 1.064 × 10- 9). Sub-group analyses revealed no significant differences due to subject age, sex, or test modality (i.e., small vs. large muscle mass exercise). However, the ES in studies using an acute dose (i.e., 0.54, 95% CI 0.37, 0.71; p = 6.774 × 10- 12) was greater (p = 0.0211) than in studies using a multiple dose regimen (i.e., 0.22, 95% CI 0.01, 0.43; p = 0.003630).

CONCLUSIONS

Acute or chronic dietary NO3- intake significantly increases maximal muscle power in humans. The magnitude of this effect-on average, ~ 5%-is likely to be of considerable practical and clinical importance.

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

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.

A single-dose nitrate-producing dietary supplement affects cardiorespiratory endurance and muscular fitness in healthy men: A randomized controlled pilot trial

Introduction:

The main aim of this pilot study was to examine the effects of a single-dose intervention with a novel nitrate-producing formulation (MagNOVOx™) on biomarkers of cardiorespiratory endurance and muscular fitness in 12 healthy men.

Methods:

The study participants (age = 22.7 ± 2.8 years, height = 184.1 ± 5.7 cm, and weight = 82.5 ± 8.4 kg) were randomly allocated to receive either a single dose of MagNOVOx™ or a placebo (inulin) in a cross-over design. The primary outcome for this study was the change in running time to exhaustion evaluated at baseline (before supplementation) and post-intervention.

Results:

Time to exhaustion was improved after the intervention in 8 out of 11 participants (72.7%) who received MagNOVOx™, and in 1 out of 11 participants (9.1%) who received placebo (p = 0.004), and MagNOVOx™ outcompeted placebo in terms of improving leg press performance (p < 0.01). No significant differences between MagNOVOx™ and placebo were found for blood pressure responses (p > 0.05).

Conclusion:

These promising findings should be further corroborated in medium- and long-term trials, and different populations, while the exact mechanism of MagNOVOx™ requires additional physiological studies.

Possible Effects of Beetroot Supplementation on Physical Performance Through Metabolic, Neuroendocrine, and Antioxidant Mechanisms: A Narrative Review of the Literature

Athletes often seek to use dietary supplements to increase performance during exercise. Among various supplements, much attention has been paid to beetroot in recent years. Beetroot is a source of carbohydrates, fiber, protein, minerals, and vitamins; also, it is a natural source of nitrate and associated with improved sports performance. Nitrates can the modification of skeletal muscle contractile proteins or calcium handling after translation. The time to reach the peak plasma nitrate is between 1 and 3 h after consumption of a single dose of nitrate. Nitrate is metabolized by conversion to nitrite and subsequently nitric oxide. Beetroot can have various effects on athletic performance through nitric oxide. Nitric oxide is an intracellular and extracellular messenger for regulating certain cellular functions and causes vasodilation of blood vessels and increases blood flow. Nitric oxide seems to be effective in improving athletic performance by increasing oxygen, glucose, and other nutrients for better muscle fueling. Nitric oxide plays the main role in anabolic hormones, modulates the release of several neurotransmitters and the major mediators of stress involved in the acute hypothalamic-pituitary-adrenal response to exercise. Beetroot is an important source of compounds such as ascorbic acid, carotenoids, phenolic acids, flavonoids, betaline, and highly active phenolics and has high antioxidant properties. Beetroot supplement provides an important source of dietary polyphenols and due to the many health benefits. Phytochemicals of Beetroot through signaling pathways inhibit inflammatory diseases. In this study, the mechanisms responsible for these effects were examined and the research in this regard was reviewed.

Influence of Dietary Nitrate Supplementation on Physical Performance and Body Composition Following Offseason Training in Division I Athletes

PURPOSE

To determine the effects of dietary nitrate supplementation, in the form of red spinach extract (RSE), on adaptations to offseason training in collegiate athletes. Methods: Sixteen Division I male baseball athletes (20.5 ± 1.7y, 90.4 ± 0.5 kg) enrolled in this study and were randomized into a RSE (n = 8) or placebo (n = 8; PL) group. Athletes completed an 11-week resistance training program during the offseason, which consisted of 2-3 workouts per week of upper and lower-body exercises and baseball-specific training. Athletes consumed a RSE (2 g; 180 mg nitrate) or PL supplement daily for the entire offseason training program. Pre and post-training, all athletes underwent one-repetition maximum (1RM) strength testing for the bench press and completed a Wingate anaerobic cycle test (WAnT). Body composition analysis was completed via a 4-compartment model, as well as muscle thickness (MT) measurement of the rectus femoris (RF) and vastus lateralis (VL) via ultrasonography. Resting heart rate and blood pressure (BP) were also obtained. Separate repeated measures analyses of variance were used to analyze all data. Results: Significant (p ≤ 0.05) main effects for time were observed for improved bench 1RM, fat-free mass, body fat percentage, RF MT, and VL MT. No significant group x time interactions (p > 0.05) were found for any measure of performance, body composition, or cardiovascular health. However, a trend for improved peak power in the WAnT was observed (p = 0.095; η²=0.200). Conclusions: These data suggest that daily RSE supplementation had no effect on performance, body composition, or cardiovascular measures in male Division I baseball players following offseason training.

Influence of Sex and Acute Beetroot Juice Supplementation on 2 KM Running Performance

Purpose: To assess the effect of acute nitrate-rich (BJ) and nitrate-depleted (PL) beetroot juice ingestion on 2 km running performance in amateur runners, and to what extent the ergogenic effect of BJ supplementation would be influenced by the sex of the participants; Methods: Twenty-four amateur long-distance runners (14 males and 10 females) performed a 2 km time trial (TT) on an outdoor athletics track 2.5 h after ingesting either 140 mL of BJ (~12.8 mmol NO3−) or PL. After the tests, blood [lactate] and ratings of perceived exertion (RPE) related to the leg muscles (RPEmuscular), cardiovascular system (RPEcardio) and general overall RPE (RPEgeneral) were assessed; Results: Compared to PL, BJ supplementation improved 2 km TT performance in both males (p < 0.05) with no supplement × sex interaction effect (p > 0.05). This improvement in 2 km running performance was a function of improved performance in the second 1 km split time in both males and females (p < 0.05). Supplementation with BJ did not alter post-exercise blood [lactate] (p > 0.05) but lowered RPEgeneral (p < 0.05); Conclusions: acute BJ supplementation improves 2 km running performance in amateur runners by enhancing performance over the second half of the TT and lowering RPEgeneral by a comparable magnitude in males and females.

Acute Effects of Caffeine Intake on Psychological Responses and High-Intensity Exercise Performance

OBJECTIVE

The aim of this study was to investigate the effects of caffeine supplementation on: (i) psychological responses of subjective vitality and mood; (ii) performance through a Wingate test; and (iii) rate of perceived exertion (RPE) reported after a Wingate test.

METHODS

Fifteen male participants (22.60 ± 2.16 years) ingested 6 mg·kg-1 of caffeine or placebo (sucrose) supplementation in two experimental sessions. After 60 min from supplement intake, participants fulfilled two questionnaires, which measured subjective vitality and mood state, respectively. Subsequently, participants' performance was assessed through a Wingate test, which was followed by measurements of RPE at general, muscular, or cardiovascular level.

RESULTS

Caffeine supplementation increased some components of mood, as assessed by profile of mood states (POMS) (tension and vigor dimensions) and subjective vitality profiles, which were followed by a greater maximum power, average power, and lower time needed to reach maximum power during the Wingate test. Moreover, lower RPE, both at muscular and general levels were reported by participants after the Wingate test.

CONCLUSIONS

These results suggest that caffeine supplementation exerts positive effects both in psychological and physical domains in trained subjects.

Acute Beetroot Juice Supplementation Attenuates Morning-Associated Decrements in Supramaximal Exercise Performance in Trained Sprinters

Diurnal fluctuations in power output have been well established with power loss typically occurring in morning (AM) times. Beetroot juice (BRJ) is a source of dietary nitrate that possess ergogenic properties, but it is unknown if ingestion can mitigate performance decrements in the morning. The purpose of this study was to examine the effects of acute BRJ supplementation on diurnal fluctuations in anaerobic performance in trained sprinters. Male Division 1 National Collegiate Athletic Association (NCAA) sprinters (n = 10) participated. In a double-blinded crossover study design, participants completed three counterbalanced exercise trials under different conditions: Morning–placebo (8:00 HR, AM-PL), Morning–BRJ (8:00 HR, AM-BRJ), and Afternoon–no supplement (15:00 HR, PM). For each trial, participants completed 3 × 15 s Wingate anaerobic tests separated by 2 min of rest. Each trial was separated by a 72 h washout period. Mean power output (p = 0.043), anaerobic capacity (p = 0.023), and total work (p = 0.026) were significantly lower with the AM-PL condition compared to PM. However, BRJ supplementation prevented AM losses of mean power output (p = 0.994), anaerobic capacity (p = 0.941), and total work (p = 0.933) in the AM-BRJ compared to the PM condition. Rate of perceived exertion was not significantly different between any conditions (p = 0.516). Heart rate was significantly lower during the AM-BRJ condition compared to AM-PL (p = 0.030) and PM (p < 0.001). Findings suggest anaerobic capacity suffers during AM versus PM times in trained sprinters, but BRJ ingestion abolishes AM-associated decrements in performance.

The Effect of Dietary Nitrate Supplementation on Isokinetic Torque in Adults: A Systematic Review and Meta-Analysis

Dietary nitrate (NO3-) supplementation, which can enhance performance in exercise settings involving repeated high-intensity efforts, has been linked to improved skeletal muscle contractile function. Although muscular strength is an important component of explosive movements and sport-specific skills, few studies have quantified indices of muscular strength following NO3- supplementation, particularly isokinetic assessments at different angular velocities. We performed a systematic review and meta-analysis to determine whether dietary NO3- supplementation improves peak torque, as assessed by the gold standard method of isokinetic dynamometry, and if this effect was linked to the angular velocity imposed during the assessment. Dialnet, Directory of Open Access Journals, MEDLINE, PubMed, SciELO, Scopus, and SPORTDiscus were searched for articles using the following search strategy: (nitrate OR beet*) AND (supplement* OR nutr* OR diet*) AND (isokinetic OR strength OR "resistance exercise" OR "resistance training" OR "muscular power"). The meta-analysis of data from 5 studies with 60 participants revealed an overall effect size of -0.01 for the effect of nitrate supplementation on isokinetic peak torque, whereas trivial effect sizes ranging from -0.11 to 0.16 were observed for independent velocity-specific (90°/s, 180°/s, 270°/s, and 360°/s) isokinetic peak torque. Four of the five studies indicated that dietary NO3- supplementation is not likely to influence voluntary knee extensor isokinetic torque across a variety of angular velocities. These results suggest that NO3- supplementation does not influence isokinetic peak torque, but further work is required to elucidate the potential of NO3- supplementation to influence other indices of muscular strength, given the dearth of experimental evidence on this topic.

Dietary Nitrate Supplementation and Exercise-Related Performance

Over the last decade, there has been a growing interest in the utility of nitrate (NO3^-) supplementation to improve exercise-related performance. After consumption, dietary NO3^- can be reduced to nitric oxide, a free radical gas involved in numerous physiological actions including blood vessel vasodilation, mitochondrial respiration, and skeletal muscle contractile function. Emerging evidence indicates that dietary NO3^- supplementation has a small but nevertheless significant beneficial effect on endurance performance through the combined effects of enhanced tissue oxygenation and metabolic efficiency in active skeletal muscle. There is further evidence to suggest that dietary NO3^- exerts a direct influence on contractile mechanisms within the skeletal muscle through alterations in calcium availability and sensitivity. Response heterogeneity and sizeable variability in the nitrate content of beetroot juice products influence the effectiveness of dietary NO3^- for exercise performance, and so dosing and product quality, as well as training history, sex, and individual-specific characteristics, should be considered.

A Randomized, Crossover Study of the Acute Cognitive and Cerebral Blood Flow Effects of Phenolic, Nitrate and Botanical Beverages in Young, Healthy Humans

Background: In whole foods, polyphenols exist alongside a wide array of other potentially bioactive phytochemicals. Yet, investigations of the effects of combinations of polyphenols with other phytochemicals are limited. Objective: The current study investigated the effects of combining extracts of beetroot, ginseng and sage with phenolic-rich apple, blueberry and coffee berry extracts. Design: This randomized, double-blind, placebo-controlled crossover design investigated three active beverages in 32 healthy adults aged 18–49 years. Each investigational beverage comprised extracts of beetroot, ginseng and sage. Each also contained a phenolic-rich extract derived from apple (containing 234 mg flavanols), blueberry (300 mg anthocyanins) or coffee berry (440 mg chlorogenic acid). Cognition, mood and CBF parameters were assessed at baseline and then again at 60, 180 and 360 min post-drink. Results: Robust effects on mood and CBF were seen for the apple and coffee berry beverages, with increased subjective energetic arousal and hemodynamic responses being observed. Fewer effects were seen with the blueberry extract beverage. Conclusions: Either the combination of beetroot, ginseng and sage was enhanced by the synergistic addition of the apple and coffee berry extract (and to a lesser extent the blueberry extract) or the former two phenolic-rich extracts were capable of evincing the robust mood and CBF effects alone.

Effects of Dietary Nitrate Supplementation on Weightlifting Exercise Performance in Healthy Adults: A Systematic Review

Dietary nitrate (NO₃⁻) supplementation has been evidenced to induce an ergogenic effect in endurance and sprint-type exercise, which may be underpinned by enhanced muscle contractility and perfusion, particularly in type II muscle fibers. However, limited data are available to evaluate the ergogenic potential of NO₃⁻ supplementation during other exercise modalities that mandate type II fiber recruitment, such as weightlifting exercise (i.e., resistance exercise). In this systematic review, we examine the existing evidence basis for NO₃⁻ supplementation to improve muscular power, velocity of contraction, and muscular endurance during weightlifting exercise in healthy adults. We also discuss the potential mechanistic bases for any positive effects of NO₃⁻ supplementation on resistance exercise performance. Dialnet, Directory of Open Access Journals, Medline, Pubmed, Scielo, Scopus and SPORT Discus databases were searched for articles using the keywords: nitrate or beetroot and supplement or nut*r or diet and strength or “resistance exercise” or “resistance training” or “muscular power”. Four articles fulfilling the inclusion criteria were identified. Two of the four studies indicated that NO₃⁻ supplementation could increase aspects of upper body weightlifting exercise (i.e., bench press) performance (increases in mean power/velocity of contraction/number of repetitions to failure), whereas another study observed an increase in the number of repetitions to failure during lower limb weightlifting exercise (i.e., back squat). Although these preliminary observations are encouraging, further research is required for the ergogenic potential of NO₃⁻ supplementation on weightlifting exercise performance to be determined.

Acute Effects of Beetroot Juice Supplements on Resistance Training: A Randomized Double-Blind Crossover

The ingestion of beetroot juice (BJ) has been associated with improvements in physical performance in endurance sports, however the literature on resistance training (RT) is scarce. The aim of this study was to investigate the acute effects of BJ compared to a placebo (PLA) on muscular endurance and movement concentric velocity during RT. Twelve healthy men performed an incremental RT test (back squat and bench press) with three sets, at 60%, 70%, and 80% of their repetition maximum (1-RM). Movement velocity variables, total number of repetitions performed until concentric failure, blood lactate, and ratings of perceived effort post-training were measured. A higher number of repetitions were recorded with BJ compared to those with PLA (13.8 ± 14.4; p < 0.01; effect size (ES) = 0.6). Differences were found at 60% 1-RM (9 ± 10; p < 0.05; ES = 0.61) and 70% 1-RM (3.1 ± 4.8; p < 0.05; ES = 0.49), however, no differences were found at 80% 1-RM (1.7 ± 1; p = 0.12; ES = 0.41). A greater number of repetitions was performed in back squat (13.4 ± 13; p < 0.01; ES = 0.77), but no differences were observed in bench press (0.4 ± 5.1; p = 0.785; ES = 0.03). No differences were found for the rest of the variables (p > 0.05). Acute supplementation of BJ improved muscular endurance performance in RT.

No Differences Between Beetroot Juice and Placebo on Competitive 5-km Running Performance: A Double-Blind, Placebo-Controlled Trial

The authors examine the effect of an acute dose of beetroot juice on endurance running performance in "real-world" competitive settings. In total, 70 recreational runners (mean ± SD: age = 33.3 ± 12.3 years, training history = 11.9 ± 8.1 years, and hours per week training = 5.9 ± 3.5) completed a quasi-randomized, double-blind, placebo-controlled study of 5-km competitive time trials. Participants performed four trials separated by 1 week in the order of prebaseline, two experimental, and one postbaseline. Experimental trials consisted of the administration of 70-ml nitrate-rich beetroot juice (containing ∼4.1 mmol of nitrate, Beet It Sport®) or nitrate-depleted placebo (containing ∼0.04 mmol of nitrate, Beet It Sport®) 2.5 hr prior to time trials. Time to complete 5 km was recorded for each trial. No differences were shown between pre- and postbaseline (p = .128, coefficient variation = 2.66%). The average of these two trials is therefore used as baseline. Compared with baseline, participants ran faster with beetroot juice (mean differences = 22.2 ± 5.0 s, p < .001, d = 0.08) and placebo (22.9 ± 4.5 s, p < .001, d = 0.09). No differences in times were shown between beetroot juice and placebo (0.8 ± 5.7 s, p < .875, d = 0.00). These results indicate that an acute dose of beetroot juice does not improve competitive 5-km time-trial performance in recreational runners compared with placebo.

Analysis of Sports Supplements Consumption in Young Spanish Elite Dinghy Sailors

The sports performance of dinghy sailors is determined by their state of nutrition and hydration. Sports supplementation plays a prominent role in elite sailors, being essential in periods of competition due to its characteristics. This study aims to analyze the consumption of sports supplements (SS) in the different categories and groups of sailors based on the level of evidence, differentiating according to sex, competitive level, and type of boat. A total of 42 sailors from national and international levels and belonging to the Laser, 420, Techno-293 and RS:X classes participated in this study. They completed a questionnaire with questions about the consumption of SS and the possible repercussions on health and/or sports performance. The results were analyzed based on the different categorizations and group organization recently established by the Australian Institute of Sport (AIS), as well as by sex, level of competition and class to which the participants belonged. The male sailors and those who competed internationally had a higher prevalence in the consumption of SS. Among the classes of vessels studied, class 420 had the lowest SS consumption. SS intake was higher during competition days, regardless of sex or level of competition. Based on the classification established by the AIS, statistically significant differences were observed in sex, level of competition, and the type of boat.

Effects of Beetroot Juice Ingestion on Physical Performance in Highly Competitive Tennis Players

Beetroot juice (BJ) contains high levels of inorganic nitrate (NO₃⁻) and its intake has good evidence in increasing blood nitrate/nitrite concentrations. The ingestion of BJ has been associated with improvements in physical performance of endurance sports, however the literature in intermittent sports is scarce. The aim of this study was to investigate whether BJ could improve physical performance in tennis players. Thirteen well-trained tennis players (25.4 ± 5.1 years) participated in the study during their preparatory period for the tennis season. Subjects were randomly divided into two groups and performed a neuromuscular test battery after either BJ or placebo (PLA) consumption. Both trials were executed on two separate days, in randomized order, with one week of wash out period. The test battery consisted of serve velocity test (SVT), countermovement jump (CMJ), isometric handgrip strength (IHS), 5-0-5 agility test (5-0-5), and 10 m sprint (10-m). No significant differences were found in SVT (1.19%; p = 0.536), CMJ (0.96%; p = 0.327), IHS (4.06%; p = 0.069), 5-0-5 dominant and nondominant side (1.11–2.02%; p = 0.071–0.191) and 10-m (1.05%; p = 0.277) when comparing BJ and PLA ingestion. Thus, our data suggest that low doses of BJ (70 mL) consumption do not enhance tennis physical performance.

Effects of caffeine supplementation on physical performance and mood dimensions in elite and trained-recreational athletes

BACKGROUND

Caffeine supplementation (CAFF) has an established ergogenic effect on physical performance and the psychological response to exercise. However, few studies have compared the response to CAFF intake among athletes of different competition level. This study compares the acute effects of CAFF on anaerobic performance, mood and perceived effort in elite and moderately-trained recreational athletes.

METHODS

Participants for this randomized, controlled, crossover study were 8 elite athletes (in the senior boxing national team) and 10 trained-recreational athletes. Under two experimental conditions, CAFF supplementation (6 mg/kg) or placebo (PLAC), the athletes completed a Wingate test. Subjective exertion during the test was recorded as the rating of perceived exertion (RPE) both at the general level (RPEgeneral) and at the levels muscular (RPEmuscular) and cardiorespiratory (RPEcardio). Before the Wingate test, participants completed the questionnaires Profiles of Moods States (POMS) and Subjective Vitality Scale (SVS).

RESULTS

In response to CAFF intake, improvements were noted in Wpeak (11.22 ± 0.65 vs 10.70 ± 0.84; p = 0.003; [Formula: see text] =0.44), Wavg (8.75 ± 0.55 vs 8.41 0.46; p = 0.001; [Formula: see text] =0.53) and time taken to reach Wpeak (7.56 ± 1.58 vs 9.11 ± 1.53; p <  0.001; [Formula: see text] =0.57) both in the elite and trained-recreational athletes. However, only the elite athletes showed significant increases in tension (+ 325%), vigor (+ 31%) and SVS (+ 28%) scores after the intake of CAFF compared to levels recorded under the condition PLAC (p <  0.05). Similarly, levels of vigor after consuming CAFF were significantly higher in the elite than the trained-recreational athletes (+ 5.8%).

CONCLUSIONS

CAFF supplementation improved anaerobic performance in both the elite and recreational athletes. However, the ergogenic effect of CAFF on several mood dimensions and subjective vitality was greater in the elite athletes.