Acute Co-Ingestion of Caffeine and Sodium Bicarbonate on Muscular Endurance Performance

Caffeine and sodium bicarbonate individually enhance muscular endurance by delaying fatigue, but their combined effects have scarcely been studied. : This study aimed to evaluate the acute effects of co-ingesting caffeine and sodium bicarbonate on muscular endurance at different loads in bench press and back squat exercises. : Twenty-seven recreationally trained participants (female/male: 14/14; age: 23 ± 3.6 years) were randomized to four conditions in a double-blind, crossover design: (a) sodium bicarbonate and caffeine (NaHCO + CAF); (b) sodium bicarbonate (NaHCO ); (c) caffeine (CAF); (d) placebo (PLA); ingesting 0.3 g/kg NaHCO , 3 mg/kg caffeine or placebo (maltodextrin). Participants performed two muscle endurance tests on bench press and back squat exercises at 65% and 85% 1RM, performing as many repetitions as possible in one set until task failure. : CAF increased the number of repetitions ( < 0.001; η = 0.111), mean velocity (V , = 0.043, η = 0.16), and mean power output (W , = 0.034, η = 0.15) compared to placebo. These effects were observed in back squat exercise at 65%1RM in V (3.7%, = 0.050, g = 1.144) and W (5.2%, = 0.047, g = 0.986) and at 85%1RM in V (5.4%, = 0.043, g = 0.22) and W (5.5%, = 0.050, g = 0.25). No ergogenic effects were found in NaHCO + CAF) or NaHCO conditions. : CAF increased muscular endurance performance in male and female participants by increasing the number of repetitions, mean velocity, and power output; however, when NaHCO was ingested, these effects were not detected.