Abstract
Purpose: sleep loss, low tolerance to fatigue are among reasons that decline the athletic performance. Thus, the aim of the study was to investigate the effect of beetroot juice on physiological fatigue (time to exhaustion and blood lactate levels) and quality of sleep among male athletes.
Methods: 30 male athletes with mean ae of 20.7±3.7 participated in the study voluntarily and divided randomly into three groups of supplement; placebo and control. Subjects in groups of supplement and placebo received 100 cc beetroot juice and placebo for a week, 2 hours prior to competition. 24-hrecall questionnaire was used to monitor the nutrition status of subjects. Blood lactate levels and time to exhaustion were measured before and after one session of high-intensive exercise. Pittsburgh Sleep Quality Index was given to filled up by the subjects before and after intervention. ANCOVA test was used to analyze the data.
Results: The results suggested that supplement group had a significant improvement in quality of sleep compared to placebo and control groups (p=0.001) while no significant difference was found between in placebo and control groups (p=0.97). In addition, both physiological fatigue indices including time to exhaustion and blood lactate levels were significantly improved after study intervention in supplement group (p≤0.05)

Conclusions: athletes are highly recommended to take beetroots supplement for the aim of postponing lactate acid accumulation. On the other hand Hence, it can be considered as a noninvasive and effective strategy to counteract sleep loss induced fatigue.

Key words: Keywords: beetroot. blood lactate, sleep, athlete.