Saturday, September 20, 2014

8g/day Citrulline Increase Leg Workout Performance - More Reps on Leg Press, Hack Squat & Leg Ext. in Exp. Gymrats

The study tested only leg exercises, but you can safely expect increased reps on other exercises, as well.
Citrulline? Yes that's the stuff the supplement industry claims to be a better version of arginine. A "super pump supplement", but not necessarily an ergogenic - in spite of the fact that corresponding evidence from rodent and human studies (Briand. 1992; Pérez-Guisado. 2010; Giannesini. 2011) existed years before the study at hand was published (Wax. 2014).

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.
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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.

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)
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.
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)
Blood lactate and heart rate, on the other hand, were significantly increased (p < 0.05) post-exercise in both groups with no significant inter-group differences between citrulline malate and placebo (p > 0.05).
Bottom line: I am not sure, if the study at hand is going to change anyone's perspective on citrulline. The "pump" is after all (for whatever reason) still what appears to be most attractive to trainees. The fact that the increased number of reps could translate into increased strength and size gains over time, on the other hand, doesn't appear sexy enough to be marketed as the main benefit of citrulline.

Can citrulline prevent muscle loss, when you're dieting | learn more
Apropos "main effect", there I guess you will remember that citrulline will also affect protein synthesis, right? I've written about these effects in August last year in my article "Citrulline = The Dieter's Amino Acid? Citrulline Maintains Muscle Protein Synthesis & Strength Endurance During Caloric Deficits Better Than Leucine!?" (read more).

So, if you don't consider increased rep numbers sexy enough, you may feel that a reduced muscle breakdown on your next diet may be worth heading over to the bulk supplier of your choice and order a 1kg bag of citrulline malate for 100$ (will last 125 days) - no? Well, honestly, I am not sure if it's worth that, either | What do you think?
  • 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).