Citrulline malate supplementation does not improve German Volume Training performance or reduce muscle soreness in moderately trained males and females

This was a randomized double blind placebo crossover study in healthy recreationally active adults who had followed structured resistance training at least twice weekly for at least 6 months. For the citrulline malate arm, 15 participants completed the protocol; 18 volunteers were enrolled overall, with 13 male and 5 female participants.

Participants consumed a single 8 g dose of citrulline malate 1.11:1 ratio (4.21 g citrulline, 3.79 g malate) as a beverage mixed with 70 ml fruit cordial and 150 ml water, taken within 5 min about 1 hour before German Volume Training. The trial used a randomized double blind placebo crossover design with two sessions under opposite treatment conditions; the placebo comparator was matched beverage.

Citrulline malate did not improve German Volume Training performance or recovery, and muscle soreness was greater than with placebo. Total repetitions were 90.9 ± 13.9 with citrulline malate versus 94.0 ± 7.9 with placebo (P = 0.33), and maximal force production was not significantly different, including isometric force (P = 0.60). Blood lactate also did not differ meaningfully: pre-GVT 1.69 ± 1.07 mmol/l versus 1.45 ± 0.54 mmol/l (P = 0.53), post-GVT 4.31 ± 1.31 mmol/l versus 4.16 ± 1.34 mmol/l (P = 0.72), and change in lactate 2.51 ± 1.53 mmol/l versus 2.87 ± 1.25 mmol/l (P = 0.48). Total muscle soreness over 72 h was significantly higher with citrulline malate (P < 0.01; CM x soreness interaction P = 0.01).

The study was small and acute, with only 15 completers in the citrulline malate arm and a single pre-exercise dose tested. The crossover design and short follow-up limit inference about chronic use or longer-term recovery. The authors also noted concern that supplement composition could have influenced results, which may affect generalizability to other citrulline malate products.