Effects of Beetroot Extract Supplementation Associated With an Exercise Protocol on Oxidative Stress, Inflammation, and Functional Capacity in Patients With Chronic Kidney Disease

This is an acute and chronic study, the acute type being a randomized, double-blind, crossover clinical trial with a washout period and placebo-controlled trial (RCT), and the chronic concerns a randomized, double-blind, placebo-controlled clinical trial type study (randomized controlled trial - RCT). To calculate the sample size, it was assumed that the tumor necrosis factor (TNF)-alpha concentration would decrease by 1.0 pg/mL after intervention with beetroot juice using the within-patient standard deviation of 2.3. It was assumed a type I error of P < 0.05 and a test power of 80%, and it was estimated that, for both the acute and chronic study, 25 patients would be needed (margin of 10%, 28 patients) with CKD undergoing conservative treatment at the Renal Nutrition Outpatient Clinic. Eligible patients of both genders, previously evaluated and authorized by the medical and nutritionist staff, will be invited to participate in the research in person and verbally, during nutritional consultations at the Renal Nutrition Outpatient Clinic. The acute intervention study will be divided into 3 stages. The first stage will consist of collecting anthropometric data, food intake, completion of individual quality of life questionnaires (SF-36) and physical activity level (IPAQ) and, finally, familiarization with the exercise protocol that will be carried out in the following stages. Already in second stage, initial data will be collected from participants, soon after, participantes will be invited to perform the 6-minute walk test. Then, all individuals will be instructed to ingest beetroot juice or placebo and wait for at least 2 hours. After 2 hours, all volunteers must complete the training protocol lasting 20 minutes. At the end of the exercises, both groups will be reevaluated. Finally, in the third and final stage, after 14 washout days participants will go through the same process described in the previous stage, however, participantes will carry out the opposite intervention to that carried out in stage two, that is, those who participated in the beetroot juice group will become part of the control group and vice versa. The chronic intervention study will be similar to the acute intervention stages, but individuals will undergo three weekly sessions, totaling 24 training sessions (8 weeks), without washout period. The second stage will begin with the collection of blood samples and vital data of participants, as well as the performance. For eight weeks, volunteers will ingest beetroot juice or control and, after 2 hours of rest, they must perform the protocol of circuit exercises. The end of this stage will be characterized by the collection of blood, vital signs, data on food intake, clinical, anthropometric, filling out questionnaires (SF-36 and IPAC) and carrying out. Before and after training, each practitioner's vital signs will be measured by security measure. If the resting heart rate is greater than 120 beats per minute (bpm), systolic blood pressure greater than 180 mmHg or diastolic blood pressure greater than 100 mmHg, the patient will be contraindicated to perform the day's training. Training should also be stopped if the subject presents chest pain, dyspnea, lower leg cramps, staggering gait, intense sweating and paleness, recommendations that will also be adopted to perform.