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blood flow, Dietary supplement, Nitrates
Introduction: Purple tea exhibits a unique composition of chemical constituents that may exert favorable outcomes related to recovery from muscle damage, improvements in blood flow, perfusion, and recovery. The purpose of this study was to examine the impact of a brief oral dosing period of purple tea in exercising humans after stressful, damaging exercise.
Methods: Using a randomized, placebo-controlled, double-blind, crossover study design, 30 healthy men (33.5 ± 11.4 years, 178.4 ± 7.6 cm, 92.5 ± 13.3 kg) completed an eight day supplementation regimen consisting of either a maltodextrin placebo or 100 mg of purple tea extract (PurpleForceTM, Oryza Oil & Fat, Ltd.) interspersed with a two week washout period. After five and eight days of supplementation, changes in muscle oxygenation, body composition, reactive hyperemia, visual analog responses, exercise performance, and muscle damage markers were assessed. Data were analyzed using mixed factorial ANOVA, t-tests with 95% confidence intervals, and effect sizes (ES).
Results: Lactate dehydrogenase was significantly reduced (p = 0.04) in PT in comparison to PLA after eight days of supplementation and exercise performance challenge. In comparison to PT, arm circumference increased in PLA after five days of supplementation (p=0.04) and tended to be greater after eight days (p=0.06). Significantly greater decreases in impedance were observed in PT (p=0.02) while between-group differences in oxygen saturation post-leg extension exercise were greater in PT 30s into recovery (p=0.04) and tended to be greater 60s after recovery (p=0.06). Total bench press repetitions completed were greater in purple tea than PLA (p = 0.001). Total leg extension repetitions completed tended to be different between groups (p=0.09) while the total number of repetitions completed in purple tea increased from day five to day eight (p<0.001) with no change in PLA (p=0.37). No between-group changes were observed in the visual analog scales; however, only the PT condition experienced a significant improvement in Willingness to Exercise (p=0.02).
Conclusions: Acute supplementation of PT decreased lactate dehydrogenase, a marker of muscle damage, while also improving lower body muscle endurance performance.
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