Citrulline and women’s fitness: what the research shows
Citrulline is an amino acid the body produces in small amounts and also gets from watermelon. Once ingested, it converts to arginine and then to nitric oxide. Nitric oxide relaxes the walls of blood vessels, widening them so more oxygen and nutrients reach working muscles.
That process is where the training benefit sits. Better blood flow means muscles fatigue more slowly and recover faster between sets. In a study of 15 resistance trained women, an 8g dose of citrulline malate taken an hour before training raised the number of reps completed on the bench press and leg press at 80 percent of one rep max. Rated effort dropped on the upper body work. A separate trial with elite female tennis players saw a 12g dose lift peak power on the Wingate cycle test and improve grip strength.
Soreness responds too. Research puts the reduction in muscle soreness after training at up to 52 percent, which shortens the gap between hard sessions and makes consistent training easier to sustain.
For older women, the picture broadens beyond the gym. A review of trials in postmenopausal women found citrulline lowered systolic blood pressure by as much as 9 mmHg in those with hypertension, and improved endothelial function, which is a measure of how well blood vessels respond to demand. Combined with resistance training, a 10g daily dose has added lean leg mass and leg strength in hypertensive postmenopausal women over eight weeks. That matters because muscle loss and vascular stiffness both accelerate after menopause, and both feed into frailty and cardiovascular risk.
Citrulline is not a rival to creatine. Creatine supports the energy system used in short, hard efforts, topping up phosphocreatine stores in the muscle. Citrulline works on the delivery side, through blood flow and nitric oxide. The two sit alongside each other in a stack aimed at strength, endurance and recovery rather than competing for the same job.
Typical doses in the research sit at 6 to 10g of citrulline (in its L form) or 8g of citrulline malate, taken 60 minutes before training or once daily for vascular benefits. Across the postmenopausal trials, no adverse effects were reported.