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Abstract

1Gadomski, S., 1Cutrufello, P., 2Zavorsky G., & 1Demkosky, C., 1University of Scranton, Scranton, PA, 2University of Louisville, Louisville, KY

Citrulline has been proposed as an ergogenic aid because of its role in both ammonia detoxification and nitric oxide production. Watermelon juice has garnered recent media attention due to its citrulline concentration, yet no study has examined watermelon juice and exercise performance. Purpose: Determine the effects of a practical, single, pre-exercise dose of L-citrulline or watermelon juice on maximal oxygen consumption (VO2max), time to exhaustion (TE), the total maximum number of repetitions completed over 5 sets (REPS), and flow-mediated vasodilation (FMD). Methods: A randomized within-subjects study design was used to examine the effects of L-citrulline and watermelon juice supplementation among twenty-two college-aged subjects (11 females; 11 males). Each subject participated in three trials where supplementation included either an 8% sucrose drink containing a 6g dose of L-citrulline, 24 oz. of watermelon juice (̴1.3 g citrulline), or an 8% sucrose placebo drink. Supplementation was administered 1 or 2 h prior to exercise testing in order to investigate a timing effect. VO2max was assessed using an incremental treadmill protocol while the total number of repetitions completed over 5 sets (30 sec rest) was determined at 80% repetition maximum on a machine bench press. FMD was examined prior to supplementation and immediately before exercise testing using ultrasound. Results: Supplementation failed to have an effect on VO2max, TTE, REPS, or FMD. There was also no interaction observed relative to gender or supplement timing (p > 0.05). Conclusion: A single dose of L-citrulline or watermelon juice as a pre-exercise supplement appears to be ineffective in improving aerobic or anaerobic exercise performance.

Research funded by an internal research grant from The University of Scranton (840690)

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