However, the study, funded by PepsiCo Inc. and published in Frontiers in Nutrition, noted that “despite molecular findings which considerably advance this field, tart cherry supplementation did not improve muscle function recovery”
Researchers at the University of Exeter, the Quadram Institute for Food, Microbiome and Health in Norwich, and other UK institutions analyzed muscle using blood samples and biopsies to assess the effects of tart cherry (TC) supplementation on exercise-induced muscle damage (EIMD)
Analysis of the proteins involved showed an increase in the expression of contractile proteins, followed by a decrease at 48 hours post-muscle damage
“An increase in contractile proteins in skeletal muscle prior to a damaging stimulus may confer a pre-conditioning effect for skeletal muscle,” wrote the researchers
They also observed that hippuric acid was positively correlated with muscle force measurements. Hippuric acid is a metabolite produced in the liver from the metabolism of dietary polyphenols (such as those in cherry juice). Low levels of hippuric acid have been associated with frailty and aging, and the current study is <a href="https://healthylife7.com/new-report-ranks-americas-100-biggest-cities-for-fitness/” title=”New report ranks America's 100 biggest cities for fitness”>reportedly the first to demonstrate the positive correlations in healthy younger adults
“These data provide important insights into the mediators of tart cherry effects in skeletal muscle, and strong potential for therapeutic and training adaptation applications,” the researchers noted
The study was a double-blinded, placebo-controlled, crossover design. Thirty-four healthy male participants completed two out of the three conditions: Low tart cherry supplementation dose (LTC), high tart cherry supplementation dose (HTC), and placebo, separated by a two-week washout period between conditions. The design ensured that the groups were matched and counterbalanced for muscle function
During each trial, participants consumed one 500-ml bottle of the allocated drink each morning for seven days. The HTC and LTC drinks contained 60 ml and 30 ml of tart cherry concentrate, respectively. The participants were also asked to minimize their intake of additional dietary polyphenols and to avoid certain high-polyphenol foods on days 7–10 of each trial
On day 8, the researchers took blood samples and performed muscle biopsies. This was followed by an exercise protocol to induce muscle damage, and additional blood and muscle samples were collected at 24 and 48 hours after the exercise
The findings showed that the supplementation “led to differential changes in skeletal muscle expression of structural and contractile proteins in response to eccentric exercise,” the researchers wrote
“Increased expression of these proteins after a seven-day tart cherry pre-load may be protective in skeletal muscle subjected to subsequent damaging exercise, although recovery of function was not enhanced in the present study,” they added
They also observed that “plasma hippuric acid was positively associated with knee extensor strength and proteins in mitochondrial and translational pathways,” noting that this is the first time this has been demonstrated in a young healthy population
“These findings suggest that TC warrants exploration as an intervention that may enhance musculoskeletal adaptations to training stimuli,” they concluded
