The ACSM recommends consumption of a carbohydrate-electrolyte drink when performing at least one hour of intense exercise. The source of carbohydrate for many traditional sports drinks is glucose or sucrose.
PURPOSE: The purpose of this study was to evaluate the effectiveness of a rice-based sports drink on metabolic changes accompanying 120 minutes of treadmill running.
METHODS: Fourteen trained men aged of 31.9 ± 6.2 yrs (Mean ± SD), with a height of 178.7 ±6. 1cm and weight of 78.1 ± 8.9 kg enrolled in this study. Percent body fat for the athletes averaged 11.9 ± 3.5%. We randomly assigned athletes to ad libitum ingestion of 3 different fluids for three 120-minute treadmill runs at 60% of VO2max, followed by a 90 minute sitting recovery period. The fluids studied consisted of a 6% carbohydrate sucrose, glucose/fructose-based sports beverage (SG), a 4.2% carbohydrate rice-based sports beverage (R) and tap water (W). The 120-minute runs were performed for 3 consecutive weeks. A VO2max test was performed for each participant for estimation of a running speed of 60% of peak capacity. Total fluid intake and total body water status using a Xitron Bio-Impedance Analyzer were assessed pre-and post-run and after recovery.
RESULTS: Average temperature and humidity during runs were 26°C (79° F) and 47% relative humidity. Mean VO2max of participants was 56.5 ± 5.4 mL/kg-1/min-1, which resulted in a mean 2 hour running speed of 6.8 ± 0.6 mph for the three runs. Rate of perceived exertion measured every 20 minutes during the runs was similar across time-points with RPE on the Borg Scale averaging 12 ± 2. Body weight decreased by 0.6 kg during the 120-minute runs, with no differences between drinks being observed (P = 0.26). Fluid consumption by the runners during the 120-minute run and recovery averaged 1.70 L and 0.63 L, respectively. No differences in consumption of the three fluids were observed during running. Although consumption was similar for SG and R (0.76 L vs. 0.61 L, P = 0.61) during recovery, the athletes consumed more SG than W during this time period (0.76 L vs. 0.52 L, P = 0.03). Furthermore, bio-impedance analysis performed during each run revealed no differences in total body water, intra-cellular water and extra-cellular water at pre-run, post-run and post-recovery time-points (all P's >0.08).
CONCLUSION: Metabolic changes accompanying 120 minutes of running were similar during runs with SG and R beverage consumption. The athletes tested were accustomed to drinking during exercise and replenished fluid adequately with whatever beverage was provided. Future studies need to examine if similar outcomes appear in recreational runners. This study was funded by Cera Products, Inc.