Background/Objective Isomaltulose is a disaccharide with a low glycaemic index and plays a role in maintaining postprandial glucose. The maintenance of glucose availability during prolonged exercise has been shown to enhance exercise performance. The present study compared the effects of pre-exercise isomaltulose versus maltodextrin ingestion on gastric parameters and cycling performance in young men. Methods Fourteen young men (mean ± S.D., age 23 ± 2 years) performed 60 min of continuous cycling at 75% of maximum heart rate followed by a 15-min exercise performance test while ingesting a 500-mL of water containing 100 mg of 13 C-sodium acetate with either 50 g of isomaltulose or 50 g of maltodextrin. Gastrointestinal discomfort was assessed periodically using an 11-point visual analogue scale throughout the study. The gastric emptying rate was evaluated periodically with the 13 C-sodium acetate breath test. For the exercise performance test, participants were instructed to pedal a cycle ergometer, exerting as much effort as possible at a self-selected pace. Results Plasma glucose and insulin concentrations measured at 30 min after ingestion were lower in the isomaltulose trial than in the maltodextrin trial. There were no differences in mean power output during the exercise performance test, gastric emptying rate or the subjective feelings of gastrointestinal discomfort between both trials. Conclusion Under the current exercise protocol, pre-exercise ingestion of isomaltulose compared with maltodextrin provided no additional benefit relative to gastric emptying or aerobic exercise performance. Both isomaltulose and maltodextrin ingestion did not influence gastrointestinal distress during 60 min of cycling and performance test.

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Background This study examined the effects of a single and continuous oral intake of L-arginine supplementation on blood metabolites and exercise performance. Methods Sixteen healthy young men (mean ± standard deviation, 23 ± 3 years) participated in a randomised, double-blind, cross-over, placebo-controlled study. For the acute trials, the participants consumed 200 mL of water containing either L-arginine (5 g) or placebo (L-arginine was replaced with dextrin) and performed cycling exercise at 75 % of heart rate reserve for 60 min, followed by a 15-min cycling performance test. The participants continued to consume each designated supplement twice a day for 13 days. For the chronic trials, the participants repeated the same protocol as the acute trials at day 15. After a 14-day washout period, the participants changed the supplement and repeated the same protocol as above. The linear mixed model was used to examine between-trial differences over the 1-day or 2-week intervention for outcome variables. Results Plasma ammonia concentrations were lower in the chronic arginine (43.5 ± 27.6 µmol/L) trial than in both acute arginine (52.1 ± 36.3 µmol/L, 95% confidence interval − 15.907 to − 1.318 µmol/L, Effect size = 0.262) and placebo (51.1 ± 32.7 µmol/L, 95% confidence interval − 14.932 to − 0.343 µmol/L, Effect size = 0.249) trials (p < 0.05). No differences were found in mean power output during the performance test between the chronic arginine (169.3 ± 8.6 W) and placebo (168.8 ± 2.3 W) trials (p > 0.05). Conclusions These results indicate that a continuous oral intake of L-arginine supplementation attenuated ammonia accumulation, but this did not influence cycling performance.