The Comparative Effect of Acute Moderate- and High-Dose Citrulline Malate on Resistance Exercise Performance in Trained Individuals: A Double-Blind Randomised Controlled Pilot Trial

Background: Citrulline malate (CM) supplementation has been shown to improve resistance exercise performance. However, there is limited research on the dose–response effects of CM ingestion. The aim of this study was to investigate a moderate (8 g; CM-MOD) and high (12 g; CM-HIGH) dose of CM on resistance exercise performance. Methods: Twelve resistance-trained individuals (7 females, 5 males, age = 24 ± 2 years; body mass = 70 ± 10 kg; height = 172 ± 7 cm) volunteered for this randomised, double-blind, crossover trial. Following a familiarisation trial that consisted of determining one repetition maximum, participants completed barbell bent-over rows and leg presses following acute ingestion of either 8 g CM (CM-MOD), 12 g CM (CM-HIGH), or a placebo 1 h prior to exercise. Each exercise comprised two sets of 10 repetitions (70% one-repetition maximum (RM)) and a third set to exhaustion at 70% 1 RM. Results: The linear mixed-effect model found no significant differences in the completed repetitions between exercise type but did reveal a significant main effect of CM-HIGH on repetitions completed (p = 0.032), which was not found for CM-MOD, and only increases in leg press repetitions were observed (estimated marginal means: placebo = 17; CM-MOD = 19; CM-HIGH = 20). Conclusions: In conclusion, CM-HIGH resulted in small improvements to total repetitions performed during resistance exercise performance and likely only during leg press activity, though the underlying mechanisms remain unclear and further investigation is warranted.