Benefits
Less loss of muscle strength after hard exercise
In a placebo-controlled trial in 44 sport-active adults, 400 mg a day of the extract led to a smaller loss of maximal leg strength over the days after an exhausting jumping workout than placebo. The muscle damage marker creatine kinase and the inflammation marker IL-6 rose in both groups and did not differ between them. This is one sponsor-funded trial.
Antioxidant enzyme activity after exercise
In the same trial, activity of glutathione peroxidase, one of the body's own antioxidant enzymes, tended to be higher with the extract after the workout, but the difference from placebo did not reach statistical significance (p = 0.068). Treat this as a signal for future studies rather than a shown effect.
Muscle soreness after exercise
Pain when getting up from a chair after the workout tended to be lower with the extract than with placebo, but the difference was not statistically significant (p = 0.079), and soreness recalled over daily life did not differ between groups (p = 0.78). A soreness benefit has not been shown.
Mechanism of action
Antioxidant polyphenols
The extract is rich in polyphenols, which act as antioxidants in laboratory studies. In the human trial an antioxidant enzyme only tended to rise after exercise, so how much this matters in people is not yet known.
Anti-inflammatory activity in laboratory work
The trial authors cite earlier laboratory work in which this extract showed anti-inflammatory activity, including blocking COX enzymes. In the human trial, the inflammation marker IL-6 rose after exercise in both groups and did not differ from placebo.
Clinical trials
Randomized, double-blind, placebo-controlled parallel trial; 400 mg a day for 10 days before a 200-jump exercise test, on the test day and for 4 days after (Buchwald-Werner et al. 2018, J Int Soc Sports Nutr)
44 healthy, sport-active men and women aged 22 to 50
Loss of maximal leg strength was smaller with the extract than with placebo (p = 0.031). Glutathione peroxidase activity (p = 0.068) and pain on movement (p = 0.079) leaned toward the extract without reaching significance; recalled soreness, creatine kinase and IL-6 did not differ between groups. No serious or product-related adverse events. Sponsored by Vital Solutions, which owns the ingredient; two authors worked for the company.