|The study tested only leg exercises, but you can safely expect increased reps on other exercises, as well.|
Benjamin Wax and his colleagues from the Mississippi State University and the Auburn University investigated the effects of citrulline malate supplementation on lower-body resistance exercise performance, blood lactate, heart rate, and blood pressure.
Based on citrulline malate’s chemical composition and a review of the current literature Wax et al. hypothesized that citrulline malate supplementation would mitigate fatigue occurring to the working muscle; therefore, augmenting resistance training performance.
To test their hypothesis the researchers recruited 12 advanced resistance trained male subjects (85kg body weight; <12% body fat; 22.1 ± 1.4 years) and conducted a randomized, counterbalanced, double blind study.
The subjects were randomly assigned to placebo or citrulline malate (8 g; 60 minutes before the workout) groups and then performed repeated bouts of multiple lower body resistance exercise:
"Subjects warmed up on an upright stationary bike (Life Fitness, Brunswick Corporation, Lake Fores, IL) for five minutes, at 60 – 70 revolution/minute with a mass of 3 – 5 kg. Following this warm up, subjects performed two warm up sets (10 repetitions at 90.9 kg and 8 repetitions at 136.4 kg) on the leg press machine. Subjects rested three minutes between sets during the warm up and trial sets.The rest periods (recovery periods between sets of exercise), exercise order, and number of sets performed were the same for all subjects in this investigation, for sessions 2 and 3. Blood lactate, heart rate, systolic blood pressure, and diastolic blood pressure were determined pre and post exercise.
Next, 60% of each subject’s predetermined 1RM was loaded on the leg press machine and the subject completed as many repetitions as possible until failure occurred. This process was completed for 4 additional sets for a total of 5 sets on the leg press. Next, the subjects performed one warm upset (10 repetitions) on the hack squat machine at a mass of 40.9 kg. This warm up set was followed by 5 sets of 60% of their predetermined 1RM to failure. Finally, following one warm up set (10 repetitions at 36.4 kg) on the leg extension, subjects completed 5 sets of 60% of their 1RM to failure." (Wax. 2014)
Practical applications - What the scientists say: "Although citrulline malate supplements are marketed to improve muscle performance via a reduction in lactic acid and ammonia production, the current study does not fully support this assertion. While our investigation did note improved muscle performance occurring during the strength protocol,blood lactate remained indifferent comparing the citrulline malate treatment to the placebo treatment. The known capacity of citrulline malate to increase plasma L-arginine (Hickner. 2006), act as a buffer to lactate and hyperammonemia (Briand. 1992; Giannesini. 2011; Verleye. 1995) remain valid; however, further research is necessary to determine which mechanism may be directly attributed ergogenic effects occurring during resistance training protocols. Finally, specific investigations utilizing training protocols designed to test muscular strength and power are warranted." (Wax. 2014)The exercise protocol resulted in sequential significant (p < 0.05) decrease in the number of repetitions in all three exercises. However, subjects in the citrulline malate group performed significantly (p < 0.05) higher number of repetitions during all three exercises compared to placebo group.
|Figure 1: Wax et al. observed significant increases in maximal leg press, hack squat, and leg extension (not shown) repetitions in response to the ingestion of 8g of citrulline malate 60min before exercise (Wax. 2014)|
- Briand, Joël, et al. "Use of a microbial model for the determination of drug effects on cell metabolism and energetics: Study of citrulline‐malate." Biopharmaceutics & drug disposition 13.1 (1992): 1-22.
- Hickner, Robert C., et al. "L-citrulline reduces time to exhaustion and insulin response to a graded exercise test." Medicine and science in sports and exercise 38.4 (2006): 660-666.
- Giannesini, Benoît, et al. "Citrulline malate supplementation increases muscle efficiency in rat skeletal muscle." European journal of pharmacology 667.1 (2011): 100-104.
- Pérez-Guisado, Joaquín, and Philip M. Jakeman. "Citrulline malate enhances athletic anaerobic performance and relieves muscle soreness." The Journal of Strength & Conditioning Research 24.5 (2010): 1215-1222.
- Verleye, M., et al. "Effects of citrulline malate on bacterial lipopolysaccharide induced endotoxemia in rats." Arzneimittelforschung 45.6 (1995): E712.
- Wax, Benjamin, et al. "Effects of Supplemental Citrulline Malate Ingestion During Repeated Bouts of Lower-body Exercise in Advanced Weight Lifters." The Journal of Strength & Conditioning Research (2014).