Acute Effects of Polyphenols from Cranberries and Grape Seeds on Endothelial Function and Performance in Elite Athletes

Acute antioxidant supplementation and performance - Should this be considered

It is well known that a training intervention leads to mitochondrial adaptations with increased skeletal muscle mitochondrial biogenesis and function. Studies have recently indicated that skeletal muscle mitochondrial function is important for athletic performance. During exercise reactive oxygen species are released from skeletal muscle potentially leading to adaptations but maybe also to fatigue. Focus has been on how chronic antioxidant supplementation affects a training adaptation, where some studies are reporting an abolished adaptation. Whether acute antioxidant supplementation could have a positive effect on fatigue and performance is interesting and highly relevant in sports where athletes are competing over several consecutive days or on the same day, with preliminary competitions in the morning and finals in the afternoon, where it is important for the athletes to recover fast. This review provides an overview of the effects of acute antioxidant supplementation and whether it leads to improved performance and/or faster recovery in humans.

Polyphenol supplementation boosts aerobic endurance in athletes: systematic review

In recent years, an increasing trend has been observed in the consumption of specific polyphenols, such as flavonoids and phenolic acids, derived from green tea, berries, and other similar sources. These compounds are believed to alleviate oxidative stress and inflammation resulting from exercise, potentially enhancing athletic performance. This systematic review critically examines the role of polyphenol supplementation in improving aerobic endurance among athletes and individuals with regular exercise habits. The review involved a thorough search of major literature databases, including PubMed, Web of Science, SCOPUS, SPORTDiscus, and Embase, covering re-search up to the year 2023. Out of 491 initially identified articles, 11 met the strict inclusion criteria for this review. These studies specifically focused on the incorporation of polyphenols or polyphenol-containing complexes in their experimental design, assessing their impact on aerobic endurance. The methodology adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, and the risk of bias was evaluated using the Cochrane bias risk assessment tool. While this review suggests that polyphenol supplementation might enhance certain aspects of aerobic endurance and promote fat oxidation, it is important to interpret these findings with caution, considering the limited number of studies available. Systematic Review Registration: https://www.crd.york.ac.uk/PROSPERO/, identifier CRD42023453321.

Cranberry supplementation improves physiological markers of performance in trained runners

PURPOSE

Cranberries have the highest polyphenol and antioxidant capacity among fruits and vegetables and may protect against exercise-induced free radical production, consequently improving performance. This study aimed to investigate the effect of polyphenol-rich cranberry extract (CE) on time-trial performance and lactate response following exercise.

METHODS

A total of 14 trained runners were tested at i) baseline, ii) 2 h following an acute CE dose (0.7 g/kg of body mass), and iii) 4 weeks after daily supplement consumption (0.3 g/kg of body mass). At each time point, runners performed a 1500-m race followed by a 400-m race where the live vastus lateralis oxygenation changes were determined by near-infrared spectroscopy and blood lactate was measured at rest and 1 and 3 min after each trial. The Shapiro-Wilk test and repeated-measures analysis of variance were used to establish significance (P <0.05).

RESULTS

Cranberry supplementation over 28 d improved aerobic performance during the 1500-m time trial, whereas the acute dose had no effect. More specifically, muscle reoxygenation rates were significantly faster after 28 d compared to baseline (P = 0.04; η² = 0.29), and a trend towards slower deoxygenation rate was observed (P = 0.13; η² = 0.20). Chronic CE consumption also buffered the post-exercise lactate response for the 400-m race (P = 0.01; η² = 0.27), while no effects were seen for the longer race.

CONCLUSION

Our results suggest that cranberry supplementation may have ergogenic effects, as it improves physiological markers of performance during short- and long-distance running.

Effect of food sources of nitrate, polyphenols, L-arginine and L-citrulline on endurance exercise performance: a systematic review and meta-analysis of randomised controlled trials

BACKGROUND

Increasing nitric oxide bioavailability may induce physiological effects that enhance endurance exercise performance. This review sought to evaluate the performance effects of consuming foods containing compounds that may promote nitric oxide bioavailability.

METHODS

Scopus, Web of Science, Ovid Medline, EMBASE and SportDiscus were searched, with included studies assessing endurance performance following consumption of foods containing nitrate, L-arginine, L-citrulline or polyphenols. Random effects meta-analysis was conducted, with subgroup analyses performed based on food sources, sex, fitness, performance test type and supplementation protocol (e.g. duration).

RESULTS

One hundred and eighteen studies were included in the meta-analysis, which encompassed 59 polyphenol studies, 56 nitrate studies and three L-citrulline studies. No effect on exercise performance following consumption of foods rich in L-citrulline was identified (SMD=-0.03, p=0.24). Trivial but significant benefits were demonstrated for consumption of nitrate and polyphenol-rich foods (SMD=0.15 and 0.17, respectively, p<0.001), including performance in time-trial, time-to-exhaustion and intermittent-type tests, and following both acute and multiple-day supplementation, but no effect of nitrate or polyphenol consumption was found in females. Among nitrate-rich foods, beneficial effects were seen for beetroot, but not red spinach or Swiss chard and rhubarb. For polyphenol-rich foods, benefits were found for grape, (nitrate-depleted) beetroot, French maritime pine, Montmorency cherry and pomegranate, while no significant effects were evident for New Zealand blackcurrant, cocoa, ginseng, green tea or raisins. Considerable heterogeneity between polyphenol studies may reflect food-specific effects or differences in study designs and subject characteristics. Well-trained males (V̇O2max ≥65 ml.kg.min-1) exhibited small, significant benefits following polyphenol, but not nitrate consumption.

CONCLUSION

Foods rich in polyphenols and nitrate provide trivial benefits for endurance exercise performance, although these effects may be food dependent. Highly trained endurance athletes do not appear to benefit from consuming nitrate-rich foods but may benefit from polyphenol consumption. Further research into food sources, dosage and supplementation duration to optimise the ergogenic response to polyphenol consumption is warranted. Further studies should evaluate whether differential sex-based responses to nitrate and polyphenol consumption are attributable to physiological differences or sample size limitations.

OTHER

The review protocol was registered on the Open Science Framework ( https://osf.io/u7nsj ) and no funding was provided.

Acute Effects of Salvia Supplementation on Cognitive Function in Athletes During a Fatiguing Cycling Exercise: A Randomized Cross-Over, Placebo-Controlled, and Double-Blind Study

Background:Salvia (sage) supplementation has been shown to improve the cognition function in healthy individuals or patients (e.g., attention, memory). To date, no study has explored its relevancy in the context of sporting performance. The aim of this study was to explore the acute effects of a combination of Salvia officinalis and Salvia lavandulaefolia on cognitive function in athletes performing a fatiguing cycling task.

Methods: Twenty-six volunteers were included in this cross-over, randomized, double-bind vs. placebo trial. Two hours before the two experimental sessions (here called SAGE and PLACEBO), volunteers randomly received a supplementation of sage or placebo. During each experimental session, participants were tested at four occasions while cycling during a warm-up, in the middle and at the end of a fatiguing task and after a short 5-min recovery. Tests included a Stroop task, a simple reaction time task, and a backward digit span memory task. Heart rate and rating of perceived exertion (RPE) were also measured at the beginning of the four test sessions.

Results: Heart rate was significantly greater during the fatiguing exercise than during warm-up and recovery (P < 0.001) without any supplementation effect. RPE was greater during the fatiguing exercise than during warm-up and recovery (P < 0.001). Moreover, RPE was significantly lower during the SAGE session as compared to PLACEBO (P = 0.002). Reaction time was not altered during the exercise but was significantly shorter with SAGE as compared to PLACEBO (P = 0.023). The Stroop task only revealed significantly longer reaction time during warm-up as compared to recovery (P = 0.02) independently of the supplementation. The digit span memory test revealed a significant greater span score with SAGE as compared to PLACEBO (P = 0.044).

Conclusion: The combination of Salvia improved the cognitive functions (perceived exertion, working memory, and reaction time). The positive effects were obtained in fresh condition and were maintained with fatigue.

Harnessing polyphenol power by targeting eNOS for vascular diseases

Vascular diseases arise due to vascular endothelium dysfunction in response to several pro-inflammatory stimuli and invading pathogens. Thickening of the vessel wall, formation of atherosclerotic plaques consisting of proliferating smooth muscle cells, macrophages and lymphocytes are the major consequences of impaired endothelium resulting in atherosclerosis, hypercholesterolemia, hypertension, type 2 diabetes mellitus, chronic renal failure and many others. Decreased nitric oxide (NO) bioavailability was found to be associated with anomalous endothelial function because of either its reduced production level by endothelial NO synthase (eNOS) which synthesize this potent endogenous vasodilator from L-arginine or its enhanced breakdown due to severe oxidative stress and eNOS uncoupling. Polyphenols are a group of bioactive compounds having more than 7000 chemical entities present in different cereals, fruits and vegetables. These natural compounds possess many OH groups which are largely responsible for their strong antioxidative, anti-inflammatory antithrombotic and anti-hypersensitive properties. Several flavonoid-derived polyphenols like flavones, isoflavones, flavanones, flavonols and anthocyanidins and non-flavonoid polyphenols like tannins, curcumins and resveratrol have attracted scientific interest for their beneficial effects in preventing endothelial dysfunction. This article will focus on in vitro as well as in vivo and clinical studies evidences of the polyphenols with eNOS modulating activity against vascular disease condition while their molecular mechanism will also be discussed.

Does red orange juice supplementation has a protective effect on performance, cardiovascular parameters, muscle damage and oxidative stress markers following the Yo-Yo Intermittent Recovery Test Level-1 under polluted air?

This study aimed to investigate the effect of red orange juice supplementation (ROJS) on performance, cardiovascular parameters, muscle damage and oxidative stress markers of athletes following exercise under polluted air. Eleven soccer players performed a Yo-Yo Intermittent Recovery Test Level-1 in polluted area (PA) and non-polluted area (NPA). Participants are invited to drink 500 ml of red orange or placebo (PLA) juice 2.5 h before the test. Blood samples were collected at rest and 3 min after each session to assess creatine kinase (CK), lactate dehydrogenase, malondialdehyde (MDA) and total antioxidant status. Our results showed that, VO_2max, heart rate and systolic blood pressure post-exercise were significantly altered by pollution with both supplements, but the damage was lowered more with ROJS than PLA. Concerning muscle damage and oxidative stress markers, orange juice supplementation blunted the effect of pollution on CK levels post-exercise (p > 0.05) and decreases significantly (p < 0.05) the MDA levels post-exercise in PA and NPA compared to PLA supplementation. In conclusion, ROJS seemed to be an appropriate strategy to reduce the risk of exposure to pollution especially on muscle damage and oxidative stress markers.

Effect of pomegranate fruit supplementation on performance and various markers in athletes and active subjects: A systematic review

The aim of the study was to review recent findings on the use of POM supplements in athletes of various disciplines and physically active participants. Eleven articles published between 2010 and 2018 were included, where the total number of investigated subjects was 176. Male participants constituted the majority of the group (n = 155), as compared to females (n = 21). 45% of research described was conducted on athletes, whereas the remaining studies were based on highly active participants. Randomised, crossover, double-blind study designs constituted the majority of the experimental designs used. POM supplementation varied in terms of form (pills/juice), dosage (50 ml-500 ml) and time of intervention (7 days-2 months) between studies. Among the reviewed articles, POM supplementation had an effect on the improvement of the following: whole body strength; feeling of vitality; acute and delayed muscle fatigue and soreness; increase in vessel diameter; blood flow and serum level of TAC; reduction in the rate of increase for HR, SBP, CK and LDH; support in the recovery of post-training CK, LDH, CRP and ASAT to their baseline levels; reduction of MMP2, MMP9, hsCRP and MDA; and increased activity of antioxidant enzymes (glutathione peroxidase and superoxide dismutase). In the majority of reviewed articles POM supplementation had a positive effect on a variety of parameters studied and the authors recommended it as a supplement for athletes and physically active bodies.

Effects of polyphenol (carob) supplementation on body composition and aerobic capacity in taekwondo athletes

Herbal products and supplements use by athletes has increased over the past decade. One such item being polyphenols. These are reported to reduce weight and modify body composition, which could aid athletes in many sports. Therefore, the purpose of the study was to determine the effect of 6 weeks supplementation with carob, a naturally occurring polyphenol, on body composition and aerobic capacity in youth taekwondo athletes. Twenty-three taekwondo athletes (21.9 ± 1.2 years; 1.64 ± 0.03 m; 67.4 ± 17.3 kg;BMI: 22.8 ± 5.5 kg/m²) participated in a short-term (6-week) double-blind randomized design parallel fully controlled training study (pre-to-post measurements): Supplemented group (SG), n = 11;placebo group (PG), n = 12. Body composition, aerobic capacity, heart rate and RPE were analyzed before and after 6 weeks of carob rich polyphenol ingestion. Significantly greater decreases in weight were observed for SG and PG (-2.82% and - 0.51%respectively) with differences between groups (p < 0.001). No significant differences were reported in percentage body fat and muscular volume between groups. Our results revealed an improvement of aerobic performance score and RPE with differences between groups. A cute polyphenol supplementation seemed to be effective in reducing body weight and improving aerobic performance in athletes.

Montmorency cherry supplementation improves 15-km cycling time-trial performance

Aim

Montmorency cherries are rich in polyphenols that possess antioxidant, anti-inflammatory and vasoactive properties. We investigated whether 7-day Montmorency cherry powder supplementation improved cycling time-trial (TT) performance.

Methods

8 trained male cyclists (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot {V}{{\text{O}}_{2{\text{peak}}}}$$\end{document}V˙O2peak: 62.3 ± 10.1 ml kg⁻¹ min⁻¹) completed 10-min steady-state (SS) cycling at ~ 65% \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot {V}{{\text{O}}_{2{\text{peak}}}}$$\end{document}V˙O2peak followed by a 15-km TT on two occasions. Participants consumed 6 pills per day (Montmorency cherry powder, MC; anthocyanin 257 mg day⁻¹ or dextrose powder, PL) for a 7-day period, 3 pills in the morning and evening. Capillary blood [lactate] was measured at baseline, post SS and post TT. Pulmonary gas exchange and tissue oxygenation index (TOI) of m. vastus lateralis via near-infrared spectroscopy, were measured throughout.

Results

TT completion time was 4.6 ± 2.9% faster following MC (1506 ± 86 s) supplementation compared to PL (1580 ± 102 s; P = 0.004). Blood [lactate] was significantly higher in MC after SS (PL: 4.4 ± 2.1 vs. MC: 6.7 ± 3.3 mM, P = 0.017) alongside an elevated baseline TOI (PL: 68.7 ± 2.1 vs. MC: 70.4 ± 2.3%, P = 0.018).

Discussion

Montmorency cherry supplementation improved 15-km cycling TT performance. This improvement in exercise performance was accompanied by enhanced muscle oxygenation suggesting that the vasoactive properties of the Montmorency cherry polyphenols may underpin the ergogenic effects.

Polyphenols and Performance: A Systematic Review and Meta-Analysis

BACKGROUND

Polyphenols exert physiological effects that may impact athletic performance. Polyphenols are antioxidants that have been noted to hinder training adaptations, yet conversely they stimulate stress-related cell signalling pathways that trigger mitochondrial biogenesis and influence vascular function.

OBJECTIVE

To determine the overall effect of polyphenols on human athletic performance.

METHODS

A search strategy was completed using MEDLINE, EMBASE, CINAHL, AMED and SPORTDiscus in April 2016. The studies were screened and independently reviewed by two researchers against predetermined criteria for eligibility. As a result of this screening, 14 studies were included for meta-analysis. Of these, the studied populations were predominately-trained males with an average intervention dose of 688 ± 478 mg·day^-1.

RESULTS

The pooled results demonstrate polyphenol supplementation for at least 7 days increases performance by 1.90% (95% CI 0.40-3.39). Sub-analysis of seven studies using quercetin identified a performance increase of 2.82% (95% CI 2.05-3.58). There were no adverse effects reported in the studies in relation to the intervention.

CONCLUSION

Overall the pooled results show that polyphenols, and of note quercetin, are viable supplements to improve performance in healthy individuals.

An Acute Dose of Specific Grape and Apple Polyphenols Improves Endurance Performance: A Randomized, Crossover, Double-Blind versus Placebo Controlled Study

Polyphenols are thought to be an interesting ergogenic aid for exercise and recovery. However, most studies regarding the effects of polyphenols investigated several days of supplementations. The present work aimed to study the effects of an acute intake of grape and apple polyphenols on the capacity to maintain intense exercise, here named endurance performance. Forty-eight physically active men (31 ± 6 years) were included in this study. During the two testing sessions, volunteers completed an endurance test at a high percentage of their maximal aerobic power and time to exhaustion was measured. Respiratory and pain parameters were also monitored. The preceding evening and 1 h before testing, volunteers had to absorb either 500 mg of polyphenols or placebo according to randomization. In comparison with the placebo, the mean duration of the maximal endurance test was significantly increased with polyphenols (+9.7% ± 6.0%, p < 0.05). The maximal perceived exertion was reached later with polyphenols (+12.8% ± 6.8%, p < 0.05). Practically, the present study showed the beneficial effects of grape and apple polyphenols for athletes looking for endurance performance improvements. The specifically designed profile of polyphenols appeared to enhance the capacity to maintain intensive efforts and delay perceived exertion.

The effect of acute pomegranate extract supplementation on oxygen uptake in highly-trained cyclists during high-intensity exercise in a high altitude environment

BACKGROUND

Recent research has indicated that pomegranate extract (POMx) may improve performance during aerobic exercise by enhancing the matching of vascular oxygen (O2) provision to muscular requirements. POMx is rich in ellagitannin polyphenols and nitrates (NO3-), which are both associated with improvements in blood flow and O2 delivery. Primarily, this study aimed to determine whether POMx improves performance in a cycling time trial to exhaustion at 100%VO2max (TTE100%) in highly-trained cyclists. In addition, we investigated if the O2 cost (VO2) of submaximal exercise was lower with POMx, and whether any changes were greater at high altitude where O2 delivery is impaired.

METHODS

Eight cyclists exercised at three submaximal intensities before completing a TTE100% at sea-level (SEA) and at 1657 m of altitude (ALT), with pre-exercise consumption of 1000 mg of POMx or a placebo (PLAC) in a randomized, double-blind, crossover design. Data were analysed using a three way (treatment x altitude x intensity) or two-way (treatment x altitude) repeated measures ANOVA with a Fisher's LSD post-hoc analysis. Significance was set at p ≤ 0.05. The effect size of significant interactions was calculated using Cohen's d.

RESULTS

TTE100% performance was reduced in ALT but was not influenced by POMx (p > 0.05). Plasma NO3- were 10.3 μmol greater with POMx vs. PLAC (95% CI, 0.8, 19.7,F1,7 = 7.83, p < 0.04). VO2 measured at five minutes into the TTE100% was significantly increased in ALTPOMx vs. ALTPLAC (+3.8 ml.min-1kg-1, 95% CI, -5.7, 9.5, F1,7 = 29.2, p = 0.001, ES = 0.6) but unchanged in SEAPOMx vs. SEAPLAC (p > 0.05). Submaximal VO2 values were not affected by POMx (p ≥ 0.05).

CONCLUSIONS

The restoration of SEA VO2 values at ALT is likely driven by the high polyphenol content of POMx, which is proposed to improve nitric oxide bioavailability. Despite an increase in VO2, no change in exercise performance occurred and therefore this study does not support the use of POMx as an ergogenic supplement.

Effects of pomegranate extract on blood flow and vessel diameter after high-intensity exercise in young, healthy adults

The effects of pomegranate extract (PE) supplementation were evaluated on high-intensity exercise performance, blood flow, vessel diameter, oxygen saturation (SPO₂), heart rate (HR), and blood pressure (BP). In a randomized, crossover design, nineteen recreationally resistance-trained participants were randomly assigned to PE (1000 mg) or placebo (PL), which were consumed 30 min prior to a repeated sprint ability (RSA) test and repetitions to fatigue (RTF) on bench and leg press. The RSA consisted of ten six-second sprints on a friction-loaded cycle ergometer with 30 s recovery. Brachial artery blood flow and vessel diameter were assessed by ultrasound. Blood flow, vessel diameter, SPO₂, HR, and BP were assessed at baseline, 30 min post ingestion, immediately post exercise (IPost), and 30 min post exercise (30minPost). With PE, blood flow significantly increased IPost RSA (mean difference = 18.49 mL min^-1; P < .05), and IPost and 30minPost RTF (P < .05) according to confidence intervals (CI). Vessel diameter increased significantly 30minPost RSA according to CI and resulted in a significant interaction IPost and 30minPost RTF (P < .05). With PE, according to CI, average and peak power output increased significantly in sprint 5 of the RSA (P < .05). There was no significant difference between PE and PL for bench (P = .25) or leg press (P = .15) repetitions. Acute PE supplementation enhanced vessel diameter and blood flow, suggesting possible exercise performance enhancement from increased delivery of substrates and oxygen. The acute timing and capsule form of PE may be advantageous to athletic populations due to ergogenic effects, taste, and convenience.

Impact of Dietary Antioxidants on Sport Performance: A Review

Many athletes supplement with antioxidants in the belief this will reduce muscle damage, immune dysfunction and fatigue, and will thus improve performance, while some evidence suggests it impairs training adaptations. Here we review the effect of a range of dietary antioxidants and their effects on sport performance, including vitamin E, quercetin, resveratrol, beetroot juice, other food-derived polyphenols, spirulina and N-acetylcysteine (NAC). Older studies suggest vitamin E improves performance at altitude, with possible harmful effects on sea-level performance. Acute intake of vitamin E is worthy of further consideration, if plasma levels can be elevated sufficiently. Quercetin has a small beneficial effect for exercise of longer duration (>100 min), but it is unclear whether this benefits athletes. Resveratrol benefits trained rodents; more research is needed in athletes. Meta-analysis of beetroot juice studies has revealed that the nitrate component of beetroot juice had a substantial but unclear effect on performance when averaged across athletes, non-athletes and modes of exercise (single dose 1.4 ± 2.0%, double dose 0.5 ± 1.9%). The effect of addition of polyphenols and other components to beetroot juice was trivial but unclear (single dose 0.4 ± 3.2%, double dose -0.5 ± 3.3%). Other food-derived polyphenols indicate a range of performance outcomes from a large improvement to moderate impairment. Limited evidence suggests spirulina enhances endurance performance. Intravenous NAC improved endurance cycling performance and reduced muscle fatigue. On the basis of vitamin E and NAC studies, acute intake of antioxidants is likely to be beneficial. However, chronic intakes of most antioxidants have a harmful effect on performance.