A comparison of isomaltulose versus maltodextrin ingestion during soccer-specific exercise

Purpose: The performance and physiological effects of isomaltulose and maltodextrin consumed intermittently during prolonged soccer-specific exercise were investigated. Methods: University soccer players (n=22) performed 120-min of intermittent exercise while consuming 8% carbohydrate-electrolyte drinks (equivalent to ~20 g·h-1) containing maltodextrin (Glycaemic Index: 90-100), isomaltulose (Glycaemic Index: 32) or a carbohydrate-energy-free placebo in a manner replicating the practices of soccer players (i.e., during warm-up and half-time). Physical (sprinting, jumping) and technical (shooting, dribbling) performance was assessed. Results: Blood glucose and plasma insulin (both P<0.001) concentrations varied by trial with isomaltulose maintaining >13% higher blood glucose concentrations between 75-90-min versus maltodextrin (P<0.05). A decline in glycaemia at 60-min in maltodextrin was attenuated with isomaltulose (-19% vs. -4%; P=0.015). Carbohydrates attenuated elevations in plasma epinephrine concentrations (P<0.05), but isomaltulose proved most effective at 90- and 120-min. Carbohydrates did not attenuate IL-6 increases or reductions in physical or technical performances (all P>0.05). Ratings of abdominal discomfort were influenced by trial (P<0.05) with lower values for both carbohydrates compared to PLA from 60-min onwards. Conclusions: Although carbohydrates (~20 g·h-1) did not attenuate performance reductions throughout prolonged soccer-specific exercise, isomaltulose maintained higher blood glucose at 75-90-min, lessened the magnitude of the exercise-induced rebound glycaemic response and attenuated epinephrine increases whilst maintaining similar abdominal discomfort values relative to maltodextrin. When limited opportunities exist to consume carbohydrates on competition-day, low-glycaemic isomaltulose may offer an alternative nutritional strategy for exercising soccer players.