ABSTRACT
Introduction:
Although sodium bicarbonate (NaHCO3) supplementation has been shown to decrease fatigue and improve high-intensity exercise performance, the effects on maintenance of isometric contractions are not clear.
Objective:
To investigate the effect of NaHCO3 on the performance of individuals subjected to a fatigue protocol in an isometric exercise on the isokinetic dynamometer.
Methods:
Participants were 12 men in a randomized, double-blind, crossover, placebo-controlled trial. Sixteen minutes after the intake of 0.3 g/kg of body mass of NaHCO3 or placebo, the participants performed an isometric fatigue protocol of right knee extension exercises during eight minutes at 70% of maximum voluntary isometric contraction. The fatigue indicator was the time point at which torque was reduced to 50% of the initial value. The length of resistance was assessed by maintaining the task over 50% of the initial torque. Lactate/blood pH concentrations and rate of perceived exertion (RPE) and pain (RPP) indexes were analyzed. The RPE of the session was evaluated 30 minutes after the test.
Results:
Blood pH was higher in pre-protocol and in the fatigue indicator after NaHCO3 intake, as were the blood lactate concentrations in the fatigue indicator and at the end of the protocol (p<0.001). NaHCO3 supplementation increased the time to fatigue and lessened the rate of decline of isometric peak torque at the end of the protocol (p<0.001). RPE and RPP were smaller at the end of the protocol in the NaHCO3 condition, and the RPE of the session was diminished (p<0.001).
Conclusion:
NaHCO3 supplementation enhances steady isometric contraction performance and reduces the internal load. Level of Evidence II; Diagnostic studies - Investigation of an examination for diagnosis.
Keywords:
Muscle fatigue; Sodium bicarbonate; Alkalosis; Exercise
