Journal Title (Medline/Pubmed accepted abbreviation): Scand. J. Med. Sci. Sports
Page numbers: 843-852
doi (if applicable): 10.1111/j.1600-0838.2009.01005.x
Summary of Background and Research Design
Background: Long distance races can induce muscle damage, inflammation, and oxidative stress. Studies have shown that foods and supplements high in antioxidants can help attenuate some of the damage. However, the studies are not consistent. Tart cherries are high in various compounds that have both antioxidant and anti-inflammatory properties.
Hypothesis/Research Question: Does consumption of tart cherry juice for 5 days before, the day of, and 2 days after the London Marathon reduce muscle damage, inflammation, and oxidative stress?
Subjects:20 distance runners- 13 male and 7 female, age 37 ± 13 for the cherry juice group and 38 ± 5 for the placebo group.
Experimental design:Participants were matched based on gender and predicted finish time and then assigned to consume either the cherry juice or a placebo in a pseudo-randomized fashion.
Treatment: 2x8 oz. of Cherrypharm cherry juice (Cherrypharm Inc., Geneva NY) per day for 5 days before the marathon, the day of, and 2 days after the marathon (8 days total). The placebo was a fruit flavored concentrate with similar sensory properties but no phytonutrients. The cherry juice provided at least 600 mg phenolics, 40 mg anthocyanins, and 560 mg of flavonoids per 8 oz.
Protocol: Markers of muscle damage, oxidative stress, and inflammation along with antioxidant status were assessed from venous blood samples 6 days before the marathon, 1 day before the marathon, immediately after the marathon, and 24 and 48 hrs afterwards. Maximum voluntary isometric contractions (MVIC) of the knee extensors was measured using a strain gauge at the same time intervals. Subjects were asked to refrain from other nutritional supplements and any strenuous exercise other than preparing for the marathon.
Summary of research findings:
Recovery of strength, as measured by the magnitude of decrement in MVIC,was greater in the cherry juice group compared to the placebo group in all time points post-marathon (group effect, p=0.024). Inflammation, as measured by serum interleukin-6 (IL-6) was significantly lower immediately post-race in the cherry group compared to the placebo group. C-reactive protein and uric acid levels also correlate with inflammation and were shown to be lower in the cherry juice group vs. the placebo group. Total antioxidant status (TAS) was increased for the cherry juice group before the race and at t= 0, 24 hr, and 48 hr post-race. Oxidative stress, as measured by thiobarbituric acid reactive species (TBARS), was higher in the placebo group at 48 hrs post-marathon compared to the cherry juice group. There were not any significant effects in other measures, including serum protein carbonyls (PCs); a measure of oxidative stress; lactate dehydrogenase; or delayed onset muscle soreness (DOMS).
Interpretation of findings/Key practice applications:
Tart cherry juice, when consumed in high quantities before, the day of, and after an endurance event, is effective at quickening recovery time, reducing oxidative stress, and reducing inflammation. It is interesting, however, that the other markers of muscle damage (e.g., creatine kinase, lactate dehydrogenase, subjective ratings of DOMS) did not improve despite the observed improvements in MVIC and antioxidant status. The reason(s) for this discrepancy are not clear.