I want to provide the perspective that does not get posted as often: I took 6g of pure L-Citrulline 45 minutes before every workout for 8 straight weeks and noticed nothing.
No enhanced pump. No extra reps. No improved recovery. No reduction in soreness. My training logs showed the same linear progression I would have expected without supplementation. My training partner, who started citrulline at the same time, was raving about the pump after week one. I felt absolutely nothing different.
I tried increasing to 8g for the last two weeks. Still nothing perceptible.
I am not saying citrulline does not work -- the clinical data is reasonably convincing, my training partner clearly responded to it, and the pharmacokinetics of arginine elevation are well-established. What I am saying is that individual variation is real, and the people who post glowing reviews are self-selecting for positive experiences.
Possible explanations I have considered: my baseline nitric oxide production may already be adequate (I eat a diet high in nitrate-rich vegetables -- beets, spinach, arugula). I may already have sufficient arginine levels from my high-protein diet (180g/day). Or my body may simply not translate the increased NO availability into subjectively perceptible performance differences.
I am not bitter about it. The supplement cost me about 30 dollars for two months, which is essentially nothing. But I want potential users to know that "your mileage may vary" is real with citrulline. If you try it for 4-6 weeks and feel nothing, that is a legitimate outcome, not evidence that you are doing it wrong.