Two weeks of watermelon juice supplementation improves nitric oxide bioavailability but not endurance exercise performance in humans

Biochemical, physiological, and performance response of a functional watermelon juice enriched in L-citrulline during a half-marathon race

“…Interestingly, in our study, participants supplemented with CWJ showed no significant decrease in jump heights while under PLA beverage the reduction in the performance was significant. Bailey et al also found over the first 10 s that the all-out effort was higher in the watermelon juice condition [21]. These findings suggest that the athletes supplemented with CWJ may perform the race with a higher intensity and with less fatigue improving their time race.…”

“…On the other hand, Hickner et al found an improvement in time to exhaustion, during an aerobic incremental test, after a dose of 3 or 9 g of l -citrulline in active subjects [22]. In the test protocol used in this study [21], each subject ran for approximately 15 min on a motorised treadmill while the speed and the grade increased until athletes could no longer continue. In addition, citrulline or citrulline malate as supplements to increase NO production do not act as stimulants and not affect HR during exercise [4].…”

“…Although the aerobic performance was analysed in the study of Cutrufello et al [20], must be taken into account that the subjects performed a Bruce test with ~ 10 min of time trial. Bailey et al also reported that volunteers did not improve time-to-exhaustion during severe-intensity exercise (a ramp incremental cycle test on an electronically-braked cycle ergometer) after receiving 16 days of supplementation with 300 mL day −1 of a watermelon juice concentrate (∼3.4 g l -citrulline day −1 ) [21]. On the other hand, Hickner et al found an improvement in time to exhaustion, during an aerobic incremental test, after a dose of 3 or 9 g of l -citrulline in active subjects [22].…”

“…For example, Cutrufello et al showed no changes in aerobic performance and physiological variables in laboratory conditions after a single dose of l -citrulline (6 g) or watermelon juice (~ 1.0 g l -citrulline) as a pre-exercise supplement in healthy male subjects [20]. In addition, Bailey et al observed no improvement in time to exhaustion during severe-intensity exercise after 16 days of watermelon juice supplementation (3.4 g of l -citrulline per day) [21]. However, Hickner et al found an increase in aerobic performance with a reduction in treadmill test time when 9 g of l -citrulline were ingested 24 h before testing in healthy male subjects under laboratory conditions [22].…”

Development of Isocratic RP-HPLC Method for Separation and Quantification of L-Citrulline and L-Arginine in Watermelons

“…Findings by Collins et al [29] proved that plasma L-arginine concentration increased by 95.2 ± 3.5  μ M and 108.0 ± 4.1  μ M compared to normal plasma baseline, 86.4 ± 3.5  μ M after 3 weeks of consumption of 780 mL (~1 g L-citrulline/day) to 1560 mL (~2 g L-citrulline/day) of watermelon juices. Recently, a study by Bailey et al [30] supported the notion of the increased plasma L-arginine concentration by 116 ± 9  μ M compared to placebo, 67 ± 13  μ M after 2 weeks of 300 mL/day watermelon juice consumption, which contains ~3.4 g L-citrulline/day. L-citrulline content in crude flesh and rind extract of red watermelon and yellow crimson watermelon varied in the range of 13.91–24.99 mg/g, while L-arginine content was in the range of 4.08–8.41 mg/g.…”