No Ergogenic Effect of Caffeine or Sodium Bicarbonate on Resistance Exercise Performance: A Double-Blind Crossover Study with Sex-Based Analysis

Caffeine, a nervous system stimulant, and sodium bicarbonate, a metabolic buffer, have been shown to improve performance in high-intensity, particularly aerobic exercises. This randomized, double-blind, placebo-controlled, crossover study compared the effects of caffeine and sodium bicarbonate on chest press (CP) and knee extension (KE) performance. Twelve resistance-trained young adults (seven females) completed three testing sessions during which they consumed caffeine (0.003g/kg body weight), sodium bicarbonate (0.3 g/kg body weight), or placebo from 120-60 minutes prior to testing. Testing consisted of 6 sets of CP and KE for as many repetitions as possible at 70% of the participants’ 1-repetition maximum load. A 60-second recovery between sets, and 2-minute recovery was allocated between exercises. Blood pressure and blood lactate were recorded pre-, mid-, and post-test. Heart rate, ratings of perceived exertion (RPE), repetitions, and electromyography (EMG) were recorded for every set. No significant differences were found for any condition for RPE, EMG, and KE repetitions. Some evidence showed increased CP repetitions with sodium bicarbonate (7.42; 95%CI: 6.8-7.9), versus caffeine (6.7; 95%CI: 6.1-7.3) and control (7.1; 95%CI: 6.4-7.6) conditions. However, post-hoc analysis did not achieve significance. Diastolic blood pressure was significantly (p=0.03) greater with caffeine (79.2 mmHg; 95%CI: 74.6-83.7) than with sodium bicarbonate (72.7 mmHg; 95%CI: 67.5-77.9) and control (74.5 mmHg; 95%CI: 71.7-77.3). Females had significantly lower blood lactate measurements, higher CP repetitions, and lower heart rates, despite similar resting heart rates between sexes. Caffeine or sodium bicarbonate did not provide ergogenic effects on CP or KE resistance training performance.