Research finds evidence of natural relief from the pain of exhaustive exercise.
Emerging research suggests tart cherry juice has a unique blend of powerful anti-inflammatory and antioxidant agents that help athletes and exercise enthusiasts recover faster from exhaustive exercise. This discovery is attracting growing interest among fitness professionals.
Recovery time is critical in helping the body adapt to the progressive overload stresses of exercise that trigger the training effect, which includes replenishing depleted energy stores, repairing damaged tissue and initiating protein synthesis (the process of increasing the protein content of muscle cells). Three key studies of the recovery benefits of tart cherry juice suggest promising results.
Why Are Tart Cherries So Helpful During Recovery?
Tart cherries contain specialized flavonoids and anthocyanins (Connolly, McHugh & Padilla-Zakour 2006). Flavonoids are plant substances thought to provide health benefits through antioxidant effects. Within cells, antioxidants are compounds that “donate” electrons to unstable molecules, also called reactive oxygen species (see Figure 1), so they don’t have to snatch electrons from unsuspecting nearby cells.
Anthocyanins are antioxidant flavonoids that protect the cells of many body systems. These plant compounds are thought to have potent antioxidant and physiological effects.
Tart cherries appear to have anti-inflammatory agents as well (Connolly, McHugh & Padilla-Zakour 2006). Acute inflammation is a protective immune response of the body to heal itself. An initial acute inflammation step is the dilation of arterioles and the opening of new capillaries to allow plasma proteins, white blood cells and immune cells to the area of injury, such as the muscle damaged by exercise. This protective process often stimulates nerves, potentially leading to irritation and pain.
Finding: Tart Cherry Juice Affects Symptoms of Muscle Damage From Eccentric Exercise
Connolly McHugh & Padilla-Zakour (2006) designed a study to determine the effect of tart cherry juice before and after eccentric exercise, which is often implicated in delayed-onset muscle soreness (DOMS). Kelley et al. (2006) had shown that eating approximately 45 Bing sweet cherries for 28 days significantly decreased some markers of inflammation in men and women. Those researchers concluded that cherries’ anti-inflammatory effects might be of clinical significance, requiring further research.
Connolly and colleagues (2006) followed up with an investigation to see whether tart cherry juice consumption before and after eccentric exercise might have a protective effect on related symptoms of muscle damage. Fourteen male college students (average age 22) drank 12 fluid ounces of a cherry juice blend (equivalent to 50–60 cherries) or a placebo twice a day (once in the morning and once in the evening) for 8 consecutive days.
The men performed a bout of eccentric elbow flexion contractions on the fourth day of supplementation. Isometric elbow flexion strength, pain, muscle tenderness and relaxed elbow angle were recorded before and for 4 days after the eccentric exercise. The men were instructed not to exercise their upper extremities during the study. In addition, they were told not to take any anti-inflammatory or pain-relieving drugs during the course of the study, nor to initiate any other treatment for symptoms of muscle soreness.
The participants performed two sets of 20 maximal eccentric contractions on a preacher-curl device with one arm, with a 3-minute rest between sets. The protocol was repeated 2 weeks later, with study subjects who initially took the placebo now taking the cherry juice drink (and vice versa). The opposite arm performed the second bout of eccentric exercise, to avoid any protective effect from a repeated bout.
In the placebo trial, strength loss was 30% 24 hours after eccentric exercise and 12% 96 hours after it. In the cherry juice trial, strength loss was only 12% after 24 hours, and strength was actually 6% above baseline after 96 hours. Most impressively, average strength loss over the 4 days after eccentric exercise was 22% with the placebo, but only 4% with the cherry juice.
Finding: Tart Cherry Juice May Reduce Pain After Extreme Exercise
Kuehl et al. (2010) noted that endurance running may cause acute muscle damage that both decreases force production and produces acute inflammation for up to 1 week after exercise. The authors proposed that this acute response to distance running may happen when disruptions of the contractile proteins create localized inflammation. The authors added that anti-inflammatory and/or antioxidant effects of cherry juice may lessen this muscle protein disruption.
Kuehl and colleagues compared the effects of tart cherry juice and a placebo cherry drink on muscle pain among the Oregon Hood-to-Coast Relay runners. The race spans 195 miles from Mount Hood to the Oregon coast with 12-person race teams (each racer runs three segments totaling about 16 miles) crossing two mountain ranges in about 28 hours. Fifty-four healthy runners (36 men, 18 women; 35.8 ± 9.6 years) volunteered for the study.
Participants running on the same relay team were assigned to the same drink condition (28 cherry juice, 26 placebo) so they could not unintentionally switch drinks during the study.
All participants completed three data collection sessions: baseline (7 days prior to the race), race start and race end. At baseline, runners in the study received 16 (12-ounce) bottles of their drink (cherry juice or placebo), with instructions to consume two bottles daily before the race (14 bottles over 7 days) and two bottles during the race (total consumption: 16 bottles). Participants assessed the intensity of their muscular pain during the race using a validated 100-millimeter visual analog scale, with 0 mm indicating no pain and 100 mm indicating most severe pain.
After completing the race, participants in both groups reported more muscle pain than they’d had at baseline. However, the increase in pain was significantly less in the cherry juice group than in the placebo group. The researchers concluded that ingesting tart cherry juice for 7 days prior to and during a strenuous running event can minimize postrun muscle pain.
Finding: Tart Cherry Juice Brings Relief After a Marathon
Howatson et al. (2010) had 20 marathon runners consume two 8-ounce bottles of a commercially blended tart cherry juice (Cherrypharm, Geneva, New York) or a placebo (one drink in the morning and one drink in the evening) for 5 days before, on the day of and for 2 days after a marathon.
After the marathon, the researchers measured several markers/signs of muscle damage, including muscle soreness, isometric strength, creatine kinase levels and lactate dehydrogenase levels. The scientists also measured indicators for inflammation, including interleukin-6, C-reactive protein and uric acid, and examined total antioxidant status and oxidative stress before and after the race.
Isometric strength recovered significantly faster in the cherry juice group. Cherry juice did not affect other muscle damage signs. Inflammation declined significantly in the cherry juice group, while total antioxidant status was about 10% greater (this is a positive outcome) in the cherry juice group than in the placebo group. The authors concluded that cherry juice appears to provide a viable way to aid recovery after strenuous exercise by increasing total antioxidative capacity, reducing inflammation and aiding in recovery of muscle function.
Tart Cherries: Final Thoughts
The totality of evidence (see Figure 2) confirms that tart cherries provide a realistic alternative to drugs and therapy in aiding recovery after exhaustive and strenuous exercise (Connolly 2015). The mechanisms appear to be related to the anti-inflammatory and antioxidant chemical properties in tart cherries.
The common dosage in most studies is an equivalent of 50 cherries per serving a day, taken twice daily (Connolly 2015). And, Connolly notes, there’s no evidence to date pointing to blood sugar irregularities, gastrointestinal complications or other symptoms from regular tart cherry intake. More research on the mechanisms by which tart cherries act and the best practices for their use is surely forthcoming.