title: Attenuated gastric distress but no benefit to performance with adaptation to octanoate-rich esterified oils in well-trained male cyclists.
abstract: We investigated the effects of modifying a normal dietary fatty acid composition and ingestion of high-fat exercise supplements on gastrointestinal distress, substrate oxidation, and endurance cycling performance. Nine well-trained male cyclists completed a randomized triple-crossover comprising a 2-wk diet high in octanoate-rich esterified oil (MCFA) or twice long-chain fatty acids (LCFA). Following the diets, participants performed 3-h of cycling at 50% of peak power followed by 10 maximal sprints while ingesting either 1) a carbohydrate (CHO)+MCFA-rich oil emulsion after the 2-wk MCFA-rich dietary condition (MC-MC, Intervention) and 2) after one of the LCFA-rich dietary conditions (LC-MC, Placebo) or 3) CHO only following a LCFA-rich diet (LC-CHO, Control). During the 3-h ride MCFA-adaptation decreased octanoic-acid oxidation by 24% (90% confidence interval: 14-34%). The CHO+MCFA-rich oil emulsion reduced endogenous fat oxidation by 61% (33-89%) and 110% (89-131%) in the MC-MC and LC-MC conditions, respectively, and MCFA-adaptation reduced endogenous-carbohydrate oxidation by 10% (-3-23%). MCFA-adaptation attenuated gastrointestinal distress and nausea during the sprints, but the effect of the oil emulsion was to lower sprint power by 10.9% (7.7-14.1%) in the LC-MC condition and by 7.1% (5.7-8.5%) in the MC-MC condition, relative to the LC-CHO control; every one unit increase in nausea decreased mean power by 6.0 W (3.2-8.8 W). We conclude that despite some attenuation of endogenous-carbohydrate oxidation and gastric distress following adaptation to a MCFA-rich diet, repeat sprint performance was substantially impaired in response to the ingestion of a CHO+MCFA-rich oil emulsion.
authors.affiliation: Institute of Food, Nutrition, and Human Health, Massey University, PO Box 756, Wellington, New Zealand.
authors.forename: Megan S
authors.initials: MS
authors.lastname: Thorburn
authors.forename: Bodil
authors.initials: B
authors.lastname: Vistisen
authors.forename: Rhys M
authors.initials: RM
authors.lastname: Thorp
authors.forename: Mike J
authors.initials: MJ
authors.lastname: Rockell
authors.forename: Asker E
authors.initials: AE
authors.lastname: Jeukendrup
authors.forename: Xuebing
authors.initials: X
authors.lastname: Xu
authors.forename: David S
authors.initials: DS
authors.lastname: Rowlands
mesh_terms: D000222:Adaptation, Physiological / Q000187:drug effects; D000284:Administration, Oral; D000328:Adult; D001642:Bicycling; D018592:Cross-Over Studies; D004041:Dietary Fats / Q000008:administration & dosage*; D004311:Double-Blind Method; D005227:Fatty Acids / Q000008:administration & dosage*; D005767:Gastrointestinal Diseases / Q000503:physiopathology* / Q000517:prevention & control*; D006801:Humans; D008297:Male; D010807:Physical Endurance / Q000187:drug effects*; D010809:Physical Fitness; D016896:Treatment Outcome
chemical_list: D004041:Dietary Fats; D005227:Fatty Acids