Acute effect of red pitaya juice supplementation on running performance and muscle damage among cadets

Red pitaya is naturally high in CHO and antioxidants that may help in improving performance and reducing delayed-onset muscle soreness (DOMS), making it a viable sports supplement option. This study investigated the acute effect of red pitaya juice (DRG) supplementation on running time-trial (TT) performance and muscle damage after a high-intensity exercise among cadets. In this randomised, single-blind, cross-over study, 11 male cadets completed two endurance running trials with either red pitaya juice (DRG; isocaloric to 6% of glucose concentration) or placebo (PLA; containing 6% glucose). Subjects consumed 350 ml of DRG or PLA 45 min before and immediately after the running trials. Then, they ran for 20 min at 75% VO2max followed by a 5-km TT with ad-libitum access to plain water. Subjects have full access to monitor the distance and to adjust the speed but were blinded to the actual speed and heart rate. The rating of perceived exertion (RPE) was assessed every 5 min during the TT and the fluid sensation scale (FSS) was measured after consuming the supplements. The biomarker of muscle damage (creatine kinase; CK), total antioxidant capacity (TAC), blood glucose and lactate levels were measured at pre-, immediately, and 24h post-exercise. There were no significant differences in the running performance (26 sec; p=0.166) between both trials and no significant differences in speed (p=0.330), heart rate (p=0.264) and RPE levels (p=0.449). There were no significant differences in blood glucose (p=0.357) and lactate level (p=0.901) between trials. However, there were significant differences in blood glucose (p=0.001) and lactate (p<0.001) levels between pre and immediately after exercise in both trials. There were no significant differences in the CK level (p=0.875) and TAC plasma level (p=0.076) between DRG and PLA trials at any time points. The FSS showed no significant differences in thirst (p=0.611), sweetness (p=0.660), nausea (p=1.000), fullness (p=0.393), and stomach upset (p=0.796) sensations between DRG and PLA trials. In conclusion, acute DRG supplementation elicited similar effects on running TT performance, blood glucose, lactate level, CK and TAC among cadets. Therefore, DRG can be considered as an alternative ergogenic aid in maintaining high-intensity endurance performance due to its similar effect with PLA.