A single dose of purple grape juice improves physical performance and antioxidant activity in runners: a randomized, crossover, double-blind, placebo study

Abstract

Purpose To investigate the effects of a single dose of juice on physical performance, oxidative stress, inflammation and muscle damage in runners. Methods Fourteen recreational male runners (39 ± 9 years, VO2peak = 55.9 ± 6.5 ml/kg/min) performed two running tests to exhaustion at 80% of VO2max after ingesting grape juice or a placebo drink (10 ml/kg/day) randomly. Blood samples were taken before and 2 h after supplementation and immediately after running to analyze total antioxidant capacity (TAC), malondialdehyde (MDA), alpha-1 acid glycoprotein (A1GPA), high-sensitivity C-reactive protein (hs-CRP), creatine kinase (CK) and lactate dehydrogenase (LDH). Results The participants ran for an average of 59.2 ± 27.8 min until exhaustion in the placebo group and for 68.4 ± 29.7 min until exhaustion in the grape juice intake group, which was a significantly longer time (p = 0.008). This improvement in physical performance was accompanied by a 43.6% increase in TAC (p = 0.000) at the post-exercise timepoint compared to the level at baseline. MDA, A1GPA, hs-CRP, CK, and LDH did not exhibit changes. In contrast, no significant change in any variable was observed after consuming the placebo drink. Conclusion The single-dose intake of purple grape juice demonstrated an ergogenic effect in recreational runners by increasing run time to exhaustion and increasing antioxidant activity.

Does Flavonoid Consumption Improve Exercise Performance? Is It Related to Changes in the Immune System and Inflammatory Biomarkers? A Systematic Review of Clinical Studies since 2005

“…Grape juice supplementation was also demonstrated to be effective in increasing performances in recreational runners who carried out four to five training sessions per week (78-min average training time/session) [ 86 ]. In addition, a recent study from the same authors concluded that just a single dose of grape juice two h before exercise is able to enhance runner performances [ 136 ]. Although the mechanisms underlying these effects remain unknown, the authors hypothesized that the anti-inflammatory, antioxidant [ 86 , 136 , 137 ], and vasodilator properties [ 138 ] of grape juice could lead to a better recovery between daily training sessions and, hence, an overall better exercise performance.…”

Effects of a Single Oral Megadose of Vitamin D3 on Inflammation and Oxidative Stress Markers in Overweight and Obese Women: A Randomized, Double-Blind, Placebo-Controlled Clinical Trial

“… 19 Total antioxidant capacity (TAC) was quantified in the plasma by measuring the scavenging activity of the free radical 2.2-diphenyl-1-picrylhydrazyl. 20 Plasma concentrations of high-sensitivity C-reactive protein (hs-CRP) and alpha-1- acid glycoprotein (A1GPA) was quantified by immunoturbidimetry using specific commercial kits (Labtest) and an automatic analyzer (LabMax 240 Premium; Labtest) according to the manufacturer’s instructions.…”

Grape polyphenols supplementation for exercise-induced oxidative stress

“…Tavares-Tocano et al [87] also showed that a single dose of purple grape juice of 10 ml/kg with a concentration of 3106.6 mg/l was able to promote increased plasma antioxidant activity in recreational male runners, but did not change the plasma concentration of lipid peroxidation by MDA.…”