Effects of Ingesting a Large Volume of Carbohydrate-Electrolyte Solution on Rehydration during Recovery and Subsequent Exercise Capacity

Abstract

This randomized, double-blind study examined the effects of rehydration per se and rehydration plus carbohydrate (CHO) ingestion during recovery (REC) on subsequent endurance running capacity. Nine men ran at 70% VáO2max on a level treadmill for 90 min (T1) on two occasions, followed by a 4 hour REC and a further exhaustive run at the same speed (T2). During the first 3 hours of REC, subjects drank either a 6.9% CHO-electrolyte solution (CE) or a CHO- and electrolyte-free sweetened placebo (PL) every 30 min. Volumes prescribed were 200% of the fluid lost after T1, but the actual volume of fluid ingested during the REC ranged from 113-200% and 88. 5-200% of the body mass lost for the CE and PL trials (NS). However, positive fluid balance was found in both trials after REC. During T2, run time was 24.3 +/- 4.4 min longer in the CE trial (69.3 +/- 5.5 vs. 45.0 +/- 4.2 min; p <.05). Higher blood glucose concentrations were observed throughout REC in the CE trial. These results suggest that ingesting a CHO-electrolyte solution is more effective in restoring endurance capacity compared to the same large volume of placebo, even though complete rehydration was achieved in both trials.

The Effect Of Sodium And Carbohydrate In A Rehydration Food On Subsequent Exercise Performance

“…Results also showed an average 22.2 min longer in time to exhaustion after rehydration with carbohydrate-electrolyte beverages. Another study supported these results using a similar protocol (47). As noted earlier, blood glucose level during prolonged exercise is mainly maintained by liver glucose output.…”

“…The higher plasma glucose concentrations during rehydration in SOUP in which CHO was ingested was in agreement with previous studies (4,38,47). The CHO dose used in previous studies ranged from 50 g to 220 g, which was greater compared to the present study (33.6 g; 0.4 g/kg BM).…”

“…The ingestion of carbohydrate during rehydration period has also shown to improve subsequent exercise (16,47). Exercise time to exhaustion was improved after CHO intakes ranging from 50 g to 220 g and large amount of water.…”

“…In all of these studies, the plasma glucose levels were elevated after CHO ingestion. Some studies reported higher plasma glucose levels after CHO ingestion compared to control (water) trials (4,38,47), while others observed higher plasma glucose than baseline, but not different than control groups. In these studies (16,42), elevated insulin was observed after CHO ingestion.…”

“…Subjects ran 22 min longer in CHO trial before they reached exhaustion. In another study (47), subjects drank either CHO-electrolyte solution (3.6 g/kg BM) or placebo equal to 200% of the fluid loss during an initial exercise bout. During a second exercise bout to exhaustion, subjects ran 24 min longer when fed CHO.…”