Acute Effect of Sodium Bicarbonate Supplementation on Symptoms of Gastrointestinal Discomfort, Acid-Base Balance, and Performance of Jiu-Jitsu Athletes.

The purpose of the present study was to verify the acute effect of sodium bicarbonate supplementation on symptoms of gastrointestinal discomfort, acid-base balance and intermittent isometric handgrip test performance in Jiu-Jitsu athletes. Ten male (22.2 ± 3.9 years; 174 ± 0.07 cm; 74.5 ± 8.9 kg) jiu-jitsu athletes participated in this counterbalanced double-blind crossover study. Two protocols, a) supplementation with 0.3 g.kg-1 of body weight of sodium bicarbonate, and b) supplementation with 0.045 g.kg-1 of body weight of placebo substance, were employed. Gastrointestinal tolerability was assessed by the questionnaire. Blood samples were collected at three time points (baseline, pre-ISO, and post-ISO) to determine the responses of potential hydrogenionic (pH), bicarbonate (HCO3- ), base excess (EB) and lactate concentrations. The maximum voluntary contraction test and the intermittent isometric contraction test were also performed. As a result, none of the athletes reported significant gastrointestinal discomfort (p > 0.05). HCO3- , pH, and EB at the pre-ISO and post-ISO moments were significantly higher for the sodium bicarbonate protocol. Lactate concentrations were significantly higher for both post-ISO protocols (p = 0.000). There was no significant difference in the performance of the maximum voluntary contraction test and the intermittent isometric contraction test (p > 0.05). Thus, we conclude that sodium bicarbonate supplementation does not generate adverse responses resulting in gastrointestinal discomfort, and does not benefit performance yet promotes a state of metabolic alkalosis.

Effects of Ischemic Preconditioning as a Warm-Up on Leg Press and Bench Press Performance.

Ischemic preconditioning (IPC) has been used to increase performance in sports. The aim of this study was to compare the acute effects of IPC with different warm-up methods on the number of repetitions and total volume in resistance exercise (RE). Sixteen healthy men recreationally trained in RE participated in this study. After the anthropometric evaluation and familiarization, a one-repetition maximum (1RM) test and retest were performed in the bench press (BP) and in the leg press 45° (LP) exercise. After these tests, participants were randomly assigned to one of the five protocols: a) IPC; b) SHAM; c) a specific warm-up (SW); d) aerobic exercise (AE), and e) active stretching (AS) prior to performing 3 sets at 80% 1RM until concentric failure. The number of repetitions was higher following IPC compared to the SW following three sets both for the BP and LP. Similarly, the number of repetitions for IPC was higher in comparison to SHAM following three sets for the LP. The number of repetitions was higher following IPC compared to AE following 1st and 2nd sets for the LP and following the 2nd set for the BP. Finally, the number of repetitions was higher following IPC compared to AS following 1st and 2nd sets for the LP. The total volume was higher following IPC compared to SHAM, SW, AE, and AS for both the BP and LP. The IPC protocol increased the number of maximum repetitions and the total volume when compared to the other tested methods, thus indicating a better utilization during the pre-work warm-up. These results indicate positive associative responses to IPC with performance maintenance, which is of importance for both athletes and coaches.