Researchers within the Center East and the UK examined the acute results of PGJ on 22 elite male under-20 soccer gamers, assessing modifications in cardio and anaerobic efficiency in a randomized, double-blind, placebo-controlled crossover examine.
They famous that the outcome “not solely displays the mixed polyphenol and carbohydrate results of PGJ but in addition helps the practicality of utilizing pure drinks as pre-exercise methods in elite athletes.”
Polyphenol sports activities supplementation
Each cardio endurance and anaerobic energy are key contributors to soccer participant efficiency, as gamers will usually cowl as much as 13 km in a given match and carry out actions resembling sprinting, leaping, tackling and kicking.
Sport dietary supplements are a typical efficiency assist, and it’s properly established that consuming carbohydrates round match time will improve endurance, nevertheless, the impression of various carbohydrate sources is under-researched, in response to the authors of the brand new examine.
Just lately, research have explored the benefits of fruit juices wealthy in carbohydrates and polyphenols, and grape juice is one that’s famous for its antioxidant properties, naturally occurring sugars, phenolic compounds and electrolytes.
Some research has already emerged to counsel that purple grape juice could enhance antioxidant exercise and endurance, having been proven to extend time to exhaustion in leisure runners. Nevertheless, one meta-analysis discovered no important impact on efficiency, seemingly because of the restricted variety of athlete-focused research.
Research particulars
The gamers accomplished two check classes, every separated by a one-week washout interval, both receiving PGJ or a placebo in 4 equal doses (10 ml/kg of physique weight), beginning 4 hours earlier than the check and at hourly intervals, with the final dose taken one hour prior. The purple grape juice was diluted to supply a 7% carbohydrate answer, whereas the placebo mimicked the juice in look, taste and quantity.
An intermittent health check was used to evaluate cardio health, consisting of 30-second bursts of operating adopted by 15 seconds of restoration, with most velocity serving as an indicator of VO₂max. Decrease-body energy was additionally evaluated by way of standing lengthy soar scores, whereas fatigue was assessed by way of a self-reported visible analog scale.
Outcomes confirmed that consuming purple grape juice on the aforementioned customized dose considerably improved cardio endurance in elite male soccer gamers by enhancing most operating velocity, time to exhaustion and VO₂max. Nevertheless, it didn’t considerably alter perceived fatigue or energy efficiency.
The researchers famous that there are a number of potential causes for the end result, noting that supplementation was seemingly to enhance endurance by supplying carbohydrates that spare muscle glycogen and preserve calcium dealing with in muscle tissue. In addition they steered that purple grape juice could delay central fatigue by decreasing serotonin manufacturing by way of lowered tryptophan uptake. Nevertheless, they attribute the insignificant distinction in perceived fatigue to the tiring nature of the train assessments.
In addition they famous that the juice’s excessive polyphenol content material might cut back oxidative stress, irritation and improve vasodilation (the widening of blood vessels because of the leisure of the blood vessel’s muscular partitions), which might in flip additional assist endurance.
“Purple grape juice supplementation enhanced endurance efficiency parameters in most contributors, with important particular person variability in response,” the researchers concluded. “These findings spotlight the potential advantages of PGJ, notably for athletes extra attentive to its results, emphasizing the necessity for customized supplementation methods.”
They famous that because of the small, homogenous group of contributors and reliance on subjective fatigue measures, future research ought to discover longer-term results, embody feminine athletes, have a look at dose-response relationships and examine the function of genetics and metabolism in PGJ’s effectiveness.
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Journal: Frontiers in Diet. doi: 10.3389/fnut.2025.1559917. “Particular person responses to purple grape juice consumption on endurance, explosive energy, and fatigue in younger male elite soccer gamers”. Authors: Niknam, A. et al.
