title: Glucose-fructose likely improves gastrointestinal comfort and endurance running performance relative to glucose-only.
abstract: This study aimed to determine whether glucose-fructose (GF) ingestion, relative to glucose-only, would alter performance, metabolism, gastrointestinal (GI) symptoms, and psychological affect during prolonged running. On two occasions, 20 runners (14 men) completed a 120-min submaximal run followed by a 4-mile time trial (TT). Participants consumed glucose-only (G) or GF (1.2:1 ratio) beverages, which supplied ∼ 1.3 g/min of carbohydrate. Substrate use, blood lactate, psychological affect [Feeling Scale (FS)], and GI distress were measured. Differences between conditions were assessed using magnitude-based inferential statistics. Participants completed the TT 1.9% (-1.9; -4.2, 0.4) faster with GF, representing a likely benefit. FS ratings were possibly higher and GI symptoms were possibly-to-likely lower with GF during the submaximal period and TT. Effect sizes for GI distress and FS ratings were relatively small (Cohen's d = ∼0.2 to 0.4). GF resulted in possibly higher fat oxidation during the submaximal period. No clear differences in lactate were observed. In conclusion, GF ingestion - compared with glucose-only - likely improves TT performance after 2 h of submaximal running, and GI distress and psychological affect are likely mechanisms. These results apply to runners consuming fluid at 500-600 mL/h and carbohydrate at 1.0-1.3 g/min during running at 60-70% VO2peak .
authors.affiliation: Nebraska Athletic Performance Laboratory, University of Nebraska-Lincoln, Lincoln, NE, USA.|Human and Sports Performance Laboratory, School of Kinesiology, University of Minnesota, Minneapolis, MN, USA.
authors.forename: P B
authors.initials: PB
authors.lastname: Wilson
authors.affiliation: Human and Sports Performance Laboratory, School of Kinesiology, University of Minnesota, Minneapolis, MN, USA.
authors.forename: S J
authors.initials: SJ
authors.lastname: Ingraham
mesh_terms: D000328:Adult; D000339:Affect / Q000187:drug effects; D054874:Athletic Performance / Q000502:physiology; D003085:Colic / Q000517:prevention & control; D018592:Cross-Over Studies; D003672:Defecation / Q000187:drug effects; D004311:Double-Blind Method; D004884:Eructation / Q000517:prevention & control; D005260:Female; D005414:Flatulence / Q000517:prevention & control; D005632:Fructose / Q000378:metabolism / Q000494:pharmacology*; D041981:Gastrointestinal Tract / Q000187:drug effects*; D005947:Glucose / Q000378:metabolism / Q000494:pharmacology*; D006801:Humans; D019344:Lactic Acid / Q000097:blood; D008297:Male; D009325:Nausea / Q000517:prevention & control; D010084:Oxidation-Reduction / Q000187:drug effects; D010807:Physical Endurance / Q000187:drug effects*; D012420:Running / Q000502:physiology* / Q000523:psychology
chemical_list: D005632:Fructose; D019344:Lactic Acid; D005947:Glucose
keywords: Endurance; exercise; exogenous; nutrition