Abstract
BackgroundTart cherry supplementation has been shown to enhance recovery from strenuous exercise due to its antioxidant properties. The majority of these studies used tart cherry juice, with a significant calorie content. The primary purpose of this study was to assess whether powdered tart cherry extract with minimal calorie content reduces oxidative stress and enhances recovery following intense resistance exercise.MethodsThirteen men (mean age: 26.2 ± 5.3 years; height: 184.3 ± 8.2 cm; weight: 92.9 ± 15.6 kg) performed a demanding resistance exercise protocol consisting of 6 sets of 10 repetitions of barbell back squat with 80% 1RM. The protocol was performed once following 7 days of 500 mg of tart cherry extract and once following placebo. Serum protein carbonyl (PC) content, creatine kinase activity (CK) and creatine kinase myocardial band content (CK-MB) were used to assess oxidative stress, skeletal and cardiac muscle damage respectively. Muscle soreness was assessed by visual analog scale. Physical performance was measured by countermovement jump power and handgrip dynamometer strength.ResultsThere was a significant increase in PC in the placebo (PL) condition when compared to the Tart Cherry (TC) condition at Immediate Post (IP) (PL: 0.4 ± 0.3 vs. TC: − 0.4 ± 0.2 nmol∙mg− 1; p < 0.001), 1 h (PL: 0.3 ± 0.3 vs. TC: − 0.7 ± 0.3 nmol∙mg− 1; p < 0.001) and 24 h (PL: 0.1 ± 0.4 vs. TC: − 0.3 ± 0.5 nmol∙mg− 1; p = 0.010). There was a significant increase in CK activity in PL when compared to the TC at IP (PL: 491.1 ± 280 vs. TC: 296.3 ± 178 U∙L− 1; p = 0.008) and 3 h (PL: − 87 ± 123 vs. TC: 43.1 ± 105.3 U∙L− 1; p = 0.006). There was a significant (p = 0.003) increase in CKMB concentration in PL when compared to the TC (PL: 21.6 ± 12.4 vs. TC: − 0.3 ± 11.8 ng∙ml− 1; p = 0.006) at 1 h post. There was a significant increase in handgrip strength in TC when compared to PL (PL: − 2 ± 5.1 vs. TC: 1.7 ± 3 kg; p = 0.017) at 24 h post.ConclusionsThis study demonstrated that tart cherry extract reduced oxidative stress and markers of muscle and cardiac damage following intense resistance exercise. This occurred along with a prevention of the decrease in handgrip strength seen following the intense exercise protocol, indicating a potential reduction in central fatigue. These benefits were seen with minimal energy intake.
Highlights
Tart cherry supplementation has been shown to enhance recovery from strenuous exercise due to its antioxidant properties
There was a statistically significant increase in protein carbonyl (PC) in the Placebo Condition when compared to the Tart Cherry Condition at Immediate Post (IP) (PL: 0.4 ± 0.3 vs. TC: − 0.4 ± 0.2 nmol∙mg− 1; p < 0.001), 1 h (PL: 0.3 ± 0.3 vs. TC: − 0.7 ± 0.3 nmol∙mg− 1; p < 0.001) and 24 (PL: 0.1 ± 0.4 vs. TC: − 0.3 ± 0.5 nmol∙mg− 1; p = 0.010)
There was a statistically significant increase in creatine kinase activity (CK) activity in the Placebo Condition when compared to the Tart Cherry Condition at IP (PL: 491.1 ± 280 vs. TC: 296.3 ± 178 U∙L− 1; p = 0.008) and 3 h (PL: − 87 ± 123 vs. TC: 43.1 ± 105.3 U∙L− 1; p = 0.006)
Summary
Tart cherry supplementation has been shown to enhance recovery from strenuous exercise due to its antioxidant properties. Resistance exercise is a powerful stimulus to induce gains in strength and hypertrophy [1] Such gains can lead to enhanced athletic performance and may reduce the demands of activities of daily living, paradoxically resistance exercise increases markers of oxidative stress [2, 3], skeletal [4] and cardiac [5] muscle damage, and transiently reduces physical performance [6]. These responses to exercise are not necessarily negative, but rather are a necessary part of the adaptation process, providing the level of stress does not exceed the ability of the body to recover. Polyphenols themselves are radical scavengers, they exist in such low concentrations in human blood that their ability to reduce markers of oxidative stress are more likely due to their capacity to enhance endogenous anti-inflammatory and antioxidant mechanisms through the nuclear factor erythroid 2-related factor 2 (Nrf2) pathway than by directly scavenging themselves [9]
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