The headline numbers, and what's behind them
Few supplement claims are as eye-catching as this one: a single 8 g dose of citrulline malate (CM) was linked to roughly 53% more bench press repetitions and about 40% less muscle soreness. Those figures come from a 2010 paper in the Journal of Strength and Conditioning Research by Pérez-Guisado and Jakeman. They are real results from a controlled trial, but they need context before you build a pre-workout routine around them.
How the study was run
Forty-one men completed two consecutive chest-training sessions of 16 sets each. The design was randomized, double-blind and crossover, which is a strong setup for a supplement trial. Each participant trained once with 8 g of CM and once with a placebo, so every lifter served as his own control. That reduces the noise from differences in strength, training history and recovery between people.
The performance test was repetitions to fatigue on flat barbell bench press at 80% of one-repetition maximum. Across eight evaluated sets, researchers counted how many reps each man could complete. Short rest periods made the session a high-intensity anaerobic challenge, which is the situation where fatigue builds quickly and any ergogenic effect should be easiest to see.
Performance: the gap widened as sets piled up
In the early sets, CM and placebo looked similar. From the third evaluated set onward, the CM condition produced significantly more repetitions (p < 0.0001). The benefit grew with each set, reaching about 52.92% more reps in the final evaluated set. All participants (100%) responded in that last set.
That detail matters. The 53% figure is not an average boost across the whole workout. It is the largest difference, seen once fatigue had accumulated. The pattern suggests CM helps most by delaying the drop-off in performance late in a session, not by raising your first-set strength. If you do a few heavy singles with long rests, this is probably not aimed at you.
Soreness: about 40% lower at 24 and 48 hours
The second finding was a roughly 40% reduction in muscle soreness at both 24 and 48 hours after training. More than 90% of participants showed a response. Delayed-onset muscle soreness peaks in that window, so a reduction there is practically meaningful for anyone training the same muscle group frequently.
A caveat is that soreness is subjective and self-reported. It can't confirm faster tissue repair or better recovery of strength. Less perceived soreness may still help someone get through the next session more comfortably.
Practical use: dose, timing and who it suits
- Dose: The study used a single 8 g dose of citrulline malate. That is the amount tied to these results, and there is no evidence here that more is better.
- Timing: Citrulline supplements are generally taken about an hour before training so levels can rise by the time you start lifting. The abstract doesn't spell out the timing, so treat 60 minutes as common practice rather than a finding of this paper.
- Who it's for: The authors point to athletes in intensive preparation or competition and to lifters doing high-volume, short-rest, high-intensity work. Think bodybuilding-style chest days, circuit-type sessions, or repeated hard efforts with limited recovery.
- Who may not need it: People doing low-volume work with long rests, or beginners whose progress is still driven by basic programming, sleep and protein intake.
Limits and side effects
The only side effect reported was stomach discomfort, in 14.63% of participants (six of 41). That is not trivial, so anyone with a sensitive gut might test the supplement on a non-critical training day first. Taking it with a small amount of fluid or food may help, though this study did not test that.
The research also has clear boundaries. All participants were men. Only one exercise, the bench press, was tested. The design looked at a single dose, not weeks of daily use. And later studies on citrulline have been more mixed, with some showing benefits and others finding little, partly because doses, formulations, exercise types and testing methods vary. This 2010 trial is a promising data point, not a final verdict.
Bottom line
The study supports the idea that 8 g of citrulline malate can help lifters sustain repetitions late in a hard, short-rest chest session and may reduce soreness over the next two days. The most defensible reading is that it's a modest, situational aid for high-volume training, with a real chance of stomach upset for some people. Expect it to complement good programming, sleep and nutrition, not replace them. If you try it, track your reps and soreness against a normal session and decide based on your own results.
