Martha P. Tarazona-Diaz et al. from the Department of Food Engineering, Universidad Politecnica de Cartagena and colleagues write: “Watermelon juice, naturally rich in L-Citrulluine, is an excellent option for athletes who want to improve their sports performance.”
But they add that this presupposed adequate bioavailability of L-Citrulluine, which occurs at highest levels in watermelons (it also occurs in other melons, squashes, cucumbers and pumpkins) and can be biosynthesized by the human body using other sources.
“This amino acid could be supplied as watermelon juice or as products enriched in citrulline from watermelon extraction. In both cases, it is important to choose watermelon cultivars rich in this amino acid,” Tarazona-Diaz et al. write.
Little interest, until now…
Until recently, the authors add, L-Citrulluine attracted little interest among the nutrition community, due to its status as a non-protein amino acid viewed solely as a metabolic intermediary in the urea cycle.
Introducing their study, the team say its antioxidant properties and ability to generate nitric oxide made it a good candidate for treating conditions such as hypertension, heart failure, atherosclerosis.
Previous studies show it might also be used to treat sickle cell disease and sexual stamina and erectile functions, they add, while other benefits associated with L-Citrulluine intake include better athletic performance due to nitric oxide synthesis and better glucose transport in skeletal muscle.
The current study involved maximum effort test using a cycloergometer by seven healthy University of Mercia sports science students (average age 22.7, standard deviation, ± 0.8 years).
On three separate occasions, each athlete drank 500ml of natural watermelon juice (1.17g of L-Citrulluine), enriched watermelon juice (4.83g of L-Citrulluine plus 1.17g from watermelon) and a placebo.
No difference in perceived exertion
Drinking the juice in both forms did not significantly improve pedalling cadence (measured in RPM) or heart rate, the scientists found, with the latter tested at the start/end of the test and during a recovery period.
There were no differences in perceived exertion, but muscle soreness 24 hours after exercise was significantly greater when cyclists drank the placebo, while results for the standard and enriched juices did not differ, indicating that 1.17g of L-Citrulluine was sufficient amino acid to help reduce physical soreness.
Title: ‘Watermelon Juice: Potential Functional Drink for Sore Muscle Relief in Athletes’
Authors: Tarazona-Díaz, M.P., Alacid, F., Carrasco, M., Martínez, I., Aguayo, E.
Source: Journal of Agricultural and Food Chemistry, Published online ahead of print July 17 2013 dx.doi.org/10.1021/jf400964r