Bicarbonato de sódio e fadiga muscular em indivíduos treinados: um ensaio clínico randomizado, cruzado, placebo controlado e duplo cego

Abstract

The early onset of muscle fatigue symptoms may be a determining factor in the definition of the resut in a competition and, thus, the use of sodium bicarbonate (NaHCO3) is an alternative used to delay the effects of this physiological condition. Therefore, the objectives of the study were: (1) to investigate the test protocols and EMG signal analysis procedures used to evaluate the effects of NaHCO3 use on muscle activity and the validity of its results; (2) to assess the immediate effect of NaHCO3 intake on trained subjects undergoing a lower limb fatigue protocol. It is a randomized, crossover, placebo-controlled, double-blind clinical trial of 12 male subjects (mean  SD, age 28.67  6.08 years, body mass 82.78  9.60 kg, height 1.78  0.09 m; Body mass index 26.51  2.26 kg), regular resistance training practitioners with experience of 6.54  3.00 years, who participated voluntarily of the tests in two conditions, being: i) experimental (EXP) that ingested 0.3 g.Kg-1 NaHCO3 and (ii) placebo (PLA) who ingested the same amount of calcium carbonate (CaCO3). Electromyography, strength, pH, lactate and questionnaires of perception of pain, effort and recovery were collected during the intermittent and high intensity dynamic isokinetic dynamometer protocol. ANOVA of repeated measures was used for statistical analysis of the data obtained and the comparison between the groups, considering the value of p < 0.05. The results of study 1 did not demonstrate the existence of an EMG signal analysis method that can be recommended as a standard to identify changes in muscle activity after NaHCO3 intake. In study 2, no significant differences were found between the conditions studied. Intake of NaHCO3 increased pH values, however, no differences in electromyographic activity, peak torque and subjective perception of exercise, recovery and pain were observed. The results demonstrate that intake of 0.3g.kg-1 NaHCO3 does not result in increased strength, altered muscle activity and perceived exertion and pain in individuals trained during the performance of an intermittent high intensity exercise in isokinetic dynamometer.