Effects of Creatine Nitrate and Caffeine Alone and Co‐ingested on Anaerobic and Muscular Endurance Performance

Abstract

BACKGROUNDIngestion of creatine nitrate and caffeine individually improve anaerobic and muscular endurance performance; however, co‐ingestion of creatine nitrate and caffeine remains unclear.METHODSIn a double‐blind, randomized, placebo‐controlled cross over study, 12 resistance‐trained participants (22±1 y; 180.0±9.5 cm; 85.9±15.1 kg) completed 4 conditions in random order: creatine nitrate (CN: 5 g/day + 0.675 g/day of maltodextrin), caffeine (CAF: 400 mg/day + 5 g/day of maltodextrin), CN+CAF (5 g/day of creatine nitrate + 400 mg/day of caffeine), and placebo (PL: 5.4 g/day of maltodextrin). Supplements were ingested for 7 days with a 7‐day washout period between conditions. Before and after supplementation, muscular endurance (bench press and leg press; 3 sets at 70% 1RM) and a Wingate anaerobic test were performed. Peak power (PP), mean power (MP), and fatigue index (FI) were calculated. Data were analyzed using a two‐way (within‐within) analysis of variance (p≤0.05) with a Tukey’s post hoc when appropriate. Absolute change (post minus pre‐testing) was calculated and analyzed with a repeated‐measures ANOVA.RESULTSThere was a significant main effect of time for both leg press (p=0.009) and bench press (p<0.001) with post‐testing greater than pre‐testing; however, there were no differences between conditions. For peak power, there was no significant interaction (p=0.436), the main effect of time (p=0.967), or differences between conditions for absolute change (p=0.436). For mean power, there was a significant interaction (p=0.037); however, post hoc analysis revealed no significant pairwise effects; however, absolute change for mean power between conditions was significant (p=0.037), with post hoc analysis revealing a trend (p<0.10) for both CN conditions (CN alone and CN+CAF) to be superior compared to CAF. There were no significant differences between conditions or overtime for fatigue index.CONCLUSIONShort‐term CN and CAF ingested either individually, or co‐ingested could not augment upper or lower body muscular endurance or anaerobic performance compared to PL in resistance‐trained participants.