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Purpose: Restoring skeletal muscle and hepatic glycogen content during short-term (<6 h) recovery from prolonged exercise is pertinent for athletes seeking to maximize performance in repeated exercise bouts. Previous research suggests that coingestion of fructose-glucose carbohydrate sources augments hepatic and has equivalent effects on skeletal muscle glycogen storage during short-term recovery from prolonged exercise compared with isocaloric glucose ingestion. The aim of the present investigation was to determine whether this has a discernible effect on subsequent exercise capacity.

Methods: Eight trained endurance runners and triathletes performed two experimental trials in a single-blind, randomized, and counterbalanced crossover design. Trials involved treadmill running to exhaustion at 70% V[spacing dot above]O2max, a 4-h recovery with 90 g[middle dot]h-1 of glucose-maltodextrin (GLU MAL) or fructose-maltodextrin (FRU MAL) ingestion (1:1.5 ratio), and a second bout of treadmill running to exhaustion at 70% V[spacing dot above]O2max.

Results: Exercise capacity in bout 2 was significantly greater with FRU MAL (81.4 /- 22.3 vs 61.4 /- 9.6 min, P = 0.02), a large magnitude effect (effect size = 1.84 /- 1.12, 32.4% /- 19.9%). Total carbohydrate oxidation rates were not significantly different during bout 1 or 2 between trials, although total carbohydrate oxidized in bout 2 was significantly greater with FRU MAL (223 /- 66 vs 157 /- 26 g, P = 0.02). Ingested carbohydrate oxidation rates were greater during bout 2 with FRU MAL (P = 0.001). Plasma glucose and nonesterified fatty acid concentrations were not significantly different between trials. Plasma lactate concentrations were significantly greater during recovery before bout 2 with FRU MAL (P = 0.001). Self-reported nausea and stomach fullness during bout 2 were marginally in favor of FRU MAL.

Conclusion: Short-term recovery of endurance capacity was significantly enhanced with FRU MAL versus GLU MAL ingestion during recovery.

(C) 2018 American College of Sports Medicine