Abstract

OBJECTIVE: This study aimed to analyze the long-term (4 weeks) effect of a diet and beetroot juice supplementation on hematological parameters, glutathione peroxidase activity in erythrocytes (GPx), and physical performance in elite fencers.

METHODS: The study included 20 fencers and was conducted during the preparatory phase. Fencers underwent the fitness VO_2max test at baseline - (B) and after two stages of implementation of the dietary recommendations – the first 4 weeks without beetroot juice (D) and the second with 26 g/d of freeze dried beetroot juice supplementation (D&J). At B and after D and D&J fasting blood samples were collected.

RESULTS: After D and D&J activities of GPx were significantly higher than those in B (p < 0.000, p = 0.005 – respectively). After D&J versus D significant increased red blood cells count (p = 0.038) and hemoglobin (p = 0.029), as well as decreased platelet count (p = 0.007), were observed. Additionally, after D&J versus B a higher level of mean platelet volume (p = 0.043), energy (p = 0.001), and carbohydrate intake (p < 0.000) were observed and a lower level of red cell distribution width (p = 0.006).

CONCLUSION: Our findings provide evidence that long-time consumption of beetroot juice may improve some hematological parameters (red blood cells count, hemoglobin, platelet count, mean platelet volume) - one of the key elements of physical performance. However, seems to be that this effect is largely determined by an appropriate level of energy and nutrients intake.

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