If you look at the ingredient list of a well-formulated pre-workout, you’ll likely find L-citrulline — often dosed at 6–8 grams. That’s no accident. L-citrulline is one of the best-evidenced compounds for improving training performance, pump and recovery, having replaced arginine as the standard ingredient in serious formulas.
How Does L-Citrulline Work?
L-citrulline is converted to L-arginine in the kidneys, which is then used to produce nitric oxide (NO) — a signalling molecule that dilates blood vessels and improves blood flow to working muscles. Despite arginine being the direct NO precursor, citrulline supplementation raises plasma arginine higher than arginine itself, because oral arginine is largely metabolised by the gut and liver (first-pass effect), while citrulline passes intact to the kidneys.
Research-Backed Training Effects
- 🏋️ More reps — An RCT (Pérez-Guisado & Jakeman, 2010) showed 8g citrulline malate increased bench press reps by 52.92% vs placebo
- ⚡ Reduced soreness — Same study reported 40% less muscle soreness at 24h and 48h post-training
- 🚴 Endurance — Meta-analyses show improved VO2max utilisation and longer time to exhaustion in cycling and running
- 💪 Pump — Enhanced blood flow produces muscle pump, which acts as a mechanical growth stimulus via cell swelling
Optimal Dosing
- ⏱️ Timing: 30–60 min before training
- 📏 Dose: 6–8g citrulline malate (2:1) or 3–5g pure L-citrulline
- 🔄 Daily use: Citrulline works cumulatively — plasma arginine increases with daily supplementation, improving effects over time
Summary
L-citrulline is one of the best-evidenced pre-workout compounds with direct effects on pump, endurance and recovery. 6–8g of citrulline malate 30–60 minutes pre-workout is the standard evidence-based dose.
