Abstract
BackgroundRecent 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.MethodsEight 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.ResultsTTE100% 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).ConclusionsThe 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.
Highlights
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
Polyphenols further enhance the effects of dietary NO3− by promoting their conversion into nitric oxide (NO) [15, 16], and protecting NO from damage caused by reactive oxygen species (ROS) [17]
Despite no overall significant effect of POMx, there appear to be two participants (HW and LS) who increased their performance with POMx in both altitudes
Summary
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. Crum et al Journal of the International Society of Sports Nutrition (2017) 14:14 contains a greater concentration of polyphenols (~3.8 mg.ml −1) than other polyphenol-rich beverages such as red wine (~3.5 mg.ml−1), Concord grape juice (~2.6 mg.ml−1) and cranberry juice (~1.7 mg.ml−1) [9]. These are predominantly from the ellagitannin (ET) subclass (80–90%) with smaller amounts of anthocyanins (8–15%) [10]. Previous research involving NO3− supplementation has predominantly used beetroot juice (BRJ), which contains ~11 mmol.L−1 NO3− [18] in comparison to 12.93 ppm.L−1 (~0.2 mmol.L−1) in POMJ and 109 ppm.L−1 (~1.76 mmol.L−1) in POMx, as reported by Roelofs et al
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